building for a sustainable future: construction without

The Institution of Structural Engineers

Building for a sustainable future:Construction without depletion

NOVEMBER 1999

The Institution of Structural Engineers11 UPPER BELGRAVE STREET, LONDON, SW1X 8BH

Constitution of Task Group

IStructE Building for a sustainable future

Michael Dickson (Buro Happold Consulting Engineers) ChairmanProfessor Bill Biggs✝ (Consultant to Buro Happold)Jennifer Jane Cornwell(Structural Consulting Engineer)Dr Satish Desai(DETR Building Regulations Division)Dr Keith Eaton (The Steel Construction Institute)Bob Gordon (MACE Limited)Steven Groak✝ (Arup Research & Development)Peter Harris (Maunsell Limited Consulting Engineers)Dr Nigel Horan (Leeds University)Dr John Menzies(Consulting Engineer)Ian Milford (W S Atkins & Partners)Mike Webster (British Cement Association)John Winter (Edward Cullinan Architects Ltd)

Terence Gray(The Institution of Structural Engineers) Secretary to the Task Group

Other contributorsPeter Charnley (Natwest Group Environmental Management)Sue Hobbs(Building Research Establishment)Anthony Hobley (Cameron McKenna)Dr Kevin McCartney (University of Portsmouth)

✝ deceased

Published by SETO, 11 Upper Belgrave Street, London SW1X 8BH

First published 1999

ISBN 1 874266 50 6

© 1999 The Institution of Structural Engineers

World Wide Web site: http://www.istructe.org.uk

Front cover: Examples of environmentally-friendly structures in different materials (clockwise fromtop left: The West Stow Country Park Museum and cafeteria (timber), the Commerzbank, Frankfurt(steel), and the new BRE Building 16 (concrete).

The Institution of Structural Engineers and the members who served on the Committee which producedthis report have endeavoured to ensure the accuracy of its contents. However, the guidance andrecommendations given in the report should always be reviewed by those using the report in the light ofthe facts of their particular case and specialist advice obtained as necessary. No liability for negligenceor otherwise in relation to this report and its contents is accepted by the Institution, the members of theCommittee, its servants or agents.

No part of this publication may be reproduced, stored in a retrieval system or transmitted in any formor by any means without prior permission of the Institution of Structural Engineers, who may becontacted at 11 Upper Belgrave Street, London SW1X 8BH.

2

Contents

IStructE Building for a sustainable future

Foreword and dedication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71.1 Introduction – towards sustainable construction . . . . . . . . . . . . . . . . . . . . . . . .81.2 Glossary of terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

2 Holistic approach to design and construction . . . . . . . . . . . . . . . . . . . . . . . . . .152.1 Input of specialisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .162.2 Input of structural engineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172.3 Project evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

3 Sustainable development policies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .213.1 International . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223.2 European . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223.3 United Kingdom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223.4 Legislation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

4 Client and user requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .254.1 Sustainable construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .264.2 Performance targets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

5 Effects of building on the environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .295.1 Environmental burden . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .305.2 Assessment of global consequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .305.3 Tasks for the development team. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .305.4 Specific tasks of the engineer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

6 Adaptability and flexibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .356.1 Long life, loose fit, low energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .366.2 Inherently inflexible aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .376.3 Keeping adequate records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

7 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .397.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .407.2 Embodied energy and operational energy . . . . . . . . . . . . . . . . . . . . . . . . . . . .407.3 Direct and indirect environmental effects . . . . . . . . . . . . . . . . . . . . . . . . . . . .447.4 Ecological properties of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .447.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

8 Designing for sustainable occupancy of a construction . . . . . . . . . . . . . . . . . . .498.1 Occupational energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .508.2 Designing for comfort . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .508.3 Insulation and infiltration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .508.4 The facade as climate moderator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .508.5 Comfort cooling and air conditioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .518.6 Natural ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .518.7 Passive design of buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53

9 Water use and water saving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .559.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .569.2 Industrial water-saving options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .579.3 Commercial and domestic water economy . . . . . . . . . . . . . . . . . . . . . . . . . . .579.4 Future developments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59

10 Contaminated land as a resource . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6110.1 Contamination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6210.2 Site investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6210.3 Risk assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63

3

4 IStructE Building for a sustainable future

10.4 Trigger concentration levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6310.5 Remedial techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6410.6 Gas generation and emission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6410.7 Landfill Tax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6410.8 Public register of land that may be contaminated . . . . . . . . . . . . . . . . . . . . .6610.9 Improvement grants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66

11 Construction as a production process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6711.1 The process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6811.2 Minimising waste on site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6811.3 Nature of site waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6811.4 Reducing environmental impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73

References, bibliography and acknowledgements . . . . . . . . . . . . . . . . . . . . . . . .75References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80

Appendices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81Appendix A Lifecycle assessment versus lifecycle costing . . . . . . . . . . . . . . . . . .82Appendix B Criteria for the selection of materials . . . . . . . . . . . . . . . . . . . . . . . .93Appendix C Centres of excellence for sustainable construction . . . . . . . . . . . . . .95

IStructE Building for a sustainable future 5

Foreword and dedication

The Task Group which compiled this report first met in November 1996 to respond tothe emerging consciousness in the engineering professions of the need to matchcontinuing improvement in the built environment to the ability for this to continue infuture generations. This is a worldwide need and appropriate and specific techniquesare needed for different economies. Essentially, the need is to continue to get betterperformance by using less primary materials and energy, wasting less and causing lessdisturbance to the natural global environment.

Naturally, for this task, our group was multi-disciplinary but with members of theInstitution of Structural Engineers in a majority to ensure a practical framework to thereport which could help engineers, designers and constructors obtain ‘more for less’ intheir daily tasks. Many are already rather good at this, provided they are able to workwithin the appropriate holistic framework.

I would like to thank the Task Group members and other contributors for theirunstinting work and expertise. I hope they enjoyed our discussions and that theyconsider this report accurately reflects their many contributions. It was an appropriateperiod to be deliberating on this important topic which spanned the Kyoto Summit(1997) and the emergence of defined government policies on ‘SustainableDevelopment’ by the UK and many other governments.

The Institution of Structural Engineers wishes to thank the members of the Committeefor giving considerably of their own time and expertise, and particularly two of theirlate members.

Steven Groak 1943-1998‘Enough is known about the earth to realise that there is a risk of plundering andpolluting the means of survival of the whole race. Communal action to avoidconfrontation and human catastrophe has to lead to continuous improvement in livingconditions. As long as people, organisations and governments really take responsibilityfor their own future actions, in answer to the ambitions expressed by the BrundtlandReport, design (in its broadest sense) can be placed at the centre “as a non-invasiveprocedure” to harness science and technology’.

Professor Bill Biggs 1923-1998‘Building is an assembly industry which buys in prefabricated components – bricksand bathrooms – and assembles them on site to someone else’s design… Design isconstrained by certain inexorable laws of mathematics and physics, of stress anddeflection, of fluid flow and power weight ratio… It is acceptance of these constraints– not of the freedoms – which leads to an understanding of quality’.

Michael DicksonTask Group ChairmanOctober 1999

6 IStructE Building for a sustainable future


Chapter 1

Introduction


1.1 Introduction: towards sustainable constructionSustainability of the built environment requires multidisciplinary, international andinterdisciplinary work over many decades using both technical and humanisticapproaches. Sustainable development needs a living language that is readilyunderstood by all people. It also calls for an ethical stance and, very often, theconfidence to depart from the norm. This places ‘design’ – by planners, developers,architects, engineers, constructors, users and manufacturers – at the centre of a processthat is understandable and holistic and focuses human ingenuity.

Our common future(The Brundtland Report) (1987)(1) stated:

‘Humanity has the ability to make development sustainable – to ensure that it meetsthe needs of the present without compromising the ability of future generations tomeet their own needs’.

Following the Rio de Janeiro Conference (1992), Guidelines on environmentalissues(2) by the Engineering Council of the United Kingdom 1994 contained muchbroad scientific and technical information on the relationships of the physicalprocesses of development to the earth’s biological and energy cycles (see Fig 1, takenfrom ref. 2).

1 Introduction

Physicalmaterials,processes

PlanetarySources

NaturalEcosystems

PlanetarySinks(Oceans, atmosphere,marine sediment, etc.)

Photo-synthesis

Otheranimalbiologicalactivity

Human Economicand Social Activity

Solar Energy

Heat loss(Infrared)

Wastes, low gradeenergy

Materials, fossil fuels,other physicalsources of energy

Organic decay

Nutrients

Food, feed,organicmaterials

Food

Food

Somerecycling

Fig 1. A full world?


This report by the Institution of Structural Engineers responds to these initiatives toguide structural engineers in the process of sustainable development around the world.Development is itself the product of urban and rural planning, architectural processesand construction activity followed by years of use, adaptations for different use andeventual recycling. It uses natural materials, consumes energy and affects local andremote habitats in the short term and is likely to have more significant future impacts.Much development is concerned with upgrading, adaptation and reuse of the buildingstock.

Although experts disagree on the extent of global climate change, sustainabledevelopment has concern for nature and for the socio-economic needs of current andfuture generations without losing cost efficiency. A total plan for sustainabilityrequires:

• Reduction of emission of greenhouse gases

• More efficient use (and reuse) of resources

• Minimisation and constructive reuse of waste

• Reduction of harmful effects from construction activities and buildingoccupation

Sustainability requires greatly reduced environmental impact and improved levels ofenergy use through continual reassessment throughout the life of the built product.This is achieved by the four Rs – Reduce, Refurbish, Reuse and Recycle (Fig 2).

Wherever possible, engineering brings to building development ‘measurement’ basedon a technical and scientific process. This process is augmented by ‘assessment’ todefine attitudes (which cannot be measured). Much architecture and commercialdevelopment succeeds because it delights the human spirit, has great functionality andis secure in its urban or rural context.

Waste

Demolish

RE-USE

REFURBISHRECYCLE

Energy andemissions at

all stages

MaterialsManufacture

ComponentManufacture

Design Construction

Buildingin Use

RawMaterials

REDUCE

Fig 2. The 4Rs – Reduce, Refurbish, Reuse and Recycle –material flows: cradle to grave

Fig 3 shows the context in which the structural engineer and others can interact tobring their particular specialisations to the many layers of project activity affecting theglobal consequence (and cost) of a proposed development.

In the creation and management of buildings, the structural engineer can participateby:

• Understanding the effects of structural engineering decisions on global warming,acid rain, ozone generation and resource depletion

• Seeking an appropriate location for the development

• Choosing a built form and orientation that contribute to environmentaleconomies and future adaptability, flexibility of use and reuse

• Selecting structural materials and systems with low embodied energy and easyreuse

• Selecting construction methods that minimise the effects of construction anddeconstruction in terms of land take, waste and pollution

Sustainable development in the built environment is not just for the altruistic. It has tobe a process driven by the narrowing gap between the economic realities of life-cyclecosting and the ecological necessities of life-cycle assessment. Sustainabledevelopment is for all cultures, climates and geographical locations and for alldisciplines.

1.2 Glossary of termsAs sustainability is, for many structural engineers and others, a new discipline, thefollowing definitions will be of assistance.

Abiotic Depletion Potential (ADP)

This concerns the extraction of non-renewable raw materials. Biotic resources, such astimber, are renewable. Most abiotic resources, such as ores, are non-renewable.

Acidification Potential (AP)

Acid deposition onto soil and into water may lead to changes in acidity, affecting bothflora and fauna.

Embodied energy

The total primary energy that has to be sequestered from a stock within the earth toproduce a specific good or service.

Ecotoxicity Aquatic/Terrestrial (ECA/ECT)

Exposure of flora and fauna to toxic substances that damage their health. Ecotoxicityis defined for water (ECA) and for soil (ECT).

Embodied carbon dioxide

The weight of carbon dioxide produced by the generation of energy needed to createthe building or component.

Energy carriers

Materials which, by chemical change, release primary energy for use in otherprocesses.

Energy Depletion Potential (EDP)

This concerns the extraction of non-renewable energy sources.

Extractive material

Material that can be extracted from the world's natural resources, such as the mining ofminerals, the cutting of timber from forests, the dredging of underwater sand, water, etc.



C1Selection of site

Feasibility study

Develop energy-efficiency requirementsand study options

C2Choice of built form

Choice of structural materials

Integration of services

C3Complete design with specifications

commissioning and handoverprocedures

Selection of tenderers conversant withenergy-efficient design

C4Ensure contractors quality controlprocedures operate satisfactorily

C5Ensure that waste minimisationprocedures are in place on site

Confirm client/tenant is familiar withenergy-efficient features and has theoperating and maintenance manual

C6Check that manuals describe efficient

operation and maintenance

C7Carry out yearly audits and

performance checksHA

ND

OV

ER

CO

NS

TR

UC

TIO

NT

EN

DE

RC

ON

CE

PT

DE

SIG

NP

LA

NN

ING

EcologyAccess

Occupation/Design lifeOutturn effectsFlexibilty/Adaptability

ClimateOrientationAvailable energy

LongevityThermal massOrientationReuse/Recycle

LocalMinimum from abroadAvailable labourStandardisationPassive systemsHuman intervention

Loadings/UseEmbodied energyTarget energy costsReuse/Recycle

Construction for minimum wasteSourced from responsible supply

Right first time

Relevant design documents andcalculations

Monitoring targets

SUSTAINABLE BUILDING DEVELOPMENT

Fig 3. Structural engineering contexts

SUSTAINABLE BUILDING DEVELOPMENT

Check that manuals describe efficientoperation and maintenance

Global Warming Potential (GWP)

The contribution to the increase in average temperature in the atmosphere, causedinitially by release of gases such as CO2, N2O and CH4 into the atmosphere.

Human toxicity (HT)

Exposure of man to toxic substances that damage health. Exposure can take placethrough air, water or soil, especially via the food chain.

Non-renewable energy

Energy which is produced from fuel sources that cannot be renewed, such as coal, gasand oil.

Nutrification Potential (NP)

Adding nutrients to water or soil increases the production of biomass. This leads to areduction in the oxygen concentration, affecting higher organisms like fish andperhaps leading to biodiversity. The main threats come from substances containingnitrogen (e.g. ammonia and NOx), phosphates and organic material.

Ozone Depletion Potential (ODP)

Depletion of the ozone layer increases the amount of ultraviolet light reaching theearth’s surface, leading possibly to human diseases and effects on ecosystems.

Passive design

The design of a building so that it exploits natural energy sources as far as possiblewith minimal need for energy input through its life.

Photochemical Oxidant Creation Potential (POCP)

Reactions of NOx with volatile organic compounds (VOC) lead, under the influence ofultraviolet light, to photochemical oxidant creation, the cause of smog.

Renewable energy

Energy which is produced from fuel sources that can be renewed, such as wind power,wave power, solar power, etc.


Fig 4. The Millennium Dome – a reusable and recyclable structure and buildingservices on a brownfield site

Recyclability

The recyclability of a material is a measure of the degree to which it can be recycledfor further use. For example, a 90% recyclability means that 90% of the material willreturn through a recycling process in order to make new material, and 10% will be lostas waste to landfill or as a yield loss in the actual process.

Sustainability

The ability of a development to meet the needs of the present without compromisingthe ability of future generations to meet theirs.



Chapter 2

Holistic approach to design andconstruction


2.1 Input of specialismsSustainability requires the design of all activities to be at the centre of thedevelopment process. Although their viewpoints will differ, all participants have to beconcerned with the global consequences of project activities for the various stages ofthe building’s life throughout the design, construction and operation process (Table 1).Structural engineering is just one of the activities within this three-dimensionalholistic approach (Fig 5).

2 Holistic approach to design andconstruction

Table 1 Effects on the environment

Effect on the environment

1. Amount of fossil fuel to purchase,process, transport and erect a givenbuilding

Embodied energy

2. Use of non-renewable resourcesOres, rock, clayExtraction

Finite materialsDamage to environmentWater requirements

3. Pollution of air, ground and watergenerated by the production. usage andfinal disposal of a given developmentCO2 released into atmosphereSO2 no gasCDC, CL, etc.

Global warmingAcid rainHoles in ozone layer

Pro

ject

act

iviti

es

Global consequencies

Client

Architect

Structural Engineer

Services Engineer

Client/Occupier

User

Manufacturer

C1

C2

C3

C4

C5

C6

C7

"Structural Engineering"a layer within aholistic 3-D approachto sustainability

Participants

Fig 5. Project activities and global consequences


2.2 Input of structural engineeringFor sustainable development, the design, specification, supervision and managementof buildings and the building process must make efficient use of resources andecological processes. This is good practice common to most engineers who follow thebasic laws of engineering to minimise waste of resources. All decisions need to betaken to ensure the development attains a plateau with a reasonable level ofsustainability (Fig 6).

Design decisions should include formal environmental assessment to assist selectionof materials and components and to determine the full life-cycle implications. Theassessment should embrace the winning and manufacturing of materials, building withthem, operating the structure and the end-of-life decisions. The selection of materialsto be used in a structure can have a significant effect on the environmental assessment;it can be particularly beneficial if the materials/components have been re-used, or ifthe materials have been produced using recycled scrap. Specific consideration shouldbe given to:

Process Burden

• Build • Energy depletion

• Repair • Biodiversity

• Refurbishment • Human health

• Reuse • Climate change

• Recycling • Resource depletion

• Demolition

• Disposal

In addition, there will be a number of more subjective areas of impact – such as urbanor rural context, visual amenity and disturbance from site noise, gas and odour –which should be considered in arriving at the chosen development.

2.3 Project evaluationInitial consideration by the design team with the client – and with the end users inmind – should include contextual evaluation, client-dependent decisions, site-dependent decisions, local requirements, and the effects on sustainability of hazardssuch as earthquakes, strong winds and mining settlement. Marking each cell in Table 2with a simple High (H), Medium (M) or Low(L) indication, where H:M:L are almost

SustainabilityHigh

Low

Too little qualityfor chosen life-cycle

Zone of sensibleengineering decision

Too much in-builtredundancy

Fig 6. Plateau of sustainable practice

an order of magnitude between each other, will soon identify critical items in relationto environmental consequences.

Each stage from inception to use and reuse will contribute differently to theenvironmental burdens. The relative importance of any one stage depends on the typeof structure. For example, a bridge is likely to have greater burdens arising frommanufacture, construction and end-of-life stages than it will from the use stage. Incontrast, an office building’s burdens are likely to be greatest during its use.


Table 3 Global consequences for all development stages

Global consequences

Resources Energy Climate Bio-diversity Human health

ADP EDO GWP ECA/ECT

AP NP POCP HT ODP

C1 Site evaluation √ √ √ √

C2 Conceptdesign

Currentoptions

√ √ √ √ √ √ √ √ √

Future options √ √

C3 Detailed design/durability √ √

C4 Manufacture √ √ √

C5 Construction/assembly √ √ √ √ √ √ √

C6 Facility management/use √ √ √

C7 End oflifedecisions

RepairRefurbishmentReuse(components)Recycle(materials)Disposal

√ √ √

Mark each cell with a H, M or L indicationEach mark in the matrix can have a descriptive text assigned to it.

Table 2 Initialising global consequence

Resources Energy Climate Bio-diversity Human health

ADP EDP GWPECA/ECT

AP NP POCP HT ODP

Projectevaluation(CO)

Contextual

Client-dependent

Site-dependent

Local humanrequirements

Resourcesavailable

As members of the specialist team, structural engineers should identify the globalconsequences of their activities (Table 3). Similar sheets should be prepared for otherparticipants to highlight incompatibilities and help ensure that the decisions takenremain on the plateau of sustainable development described previously.


Fig 7. St John’s Innovation Centre, Cambridge


Chapter 3

Sustainable development policies


3.1 InternationalThe report Our common future(1) (1987) from the World Commission on Environmentand Development (Brundtland Commission) established sustainable development as abroad global objective. In 1992, the UN Conference on Environment andDevelopment held in Rio de Janiero attended by 176 nations and manyintergovernmental organisations produced Agenda 21 Programme of action forsustainable development(3), including sustainable human settlement and population,sustainable agriculture and rural development.

In 1996, the Habitat II UN Conference in Istanbul tackled the need to design andmanage sustainable developments and in 1997 the UN Earth Summit II assessedprogress towards sustainable development and implementation of Agenda 21.

There are many international treaties based on the principle of sustainabledevelopment. The Basel Convention on Control of transboundary movement ofhazardous wastes and their disposal(4) is one example.

3.2 EuropeanIn 1992, the Maastricht Treaty(5) on European Union introduced the aim of sustainablegrowth respecting the environment (Article 2) under which the 5th EC EnvironmentalAction Programme was launched, under the title ‘Towards sustainability’. The ECConsultative Forum on Environment Sustainable Development was set up in 1997.

3.3 United KingdomThe UK has adopted a multifaceted approach:

• A strategic approach with white papers setting out national strategies to integratesustainable development into policy making and the setting up of think tanks

• Monitoring and reporting under the UK ‘Strategy for sustainable development’and the ‘Set of indicators for sustainable development for the UK’.

• Engaging businesses, non-governmental organisations and local authorities andpartnerships such as local Agenda 21.

• Legislation: see 3.4.

1990 White Paper – This common inheritance(6)

1994 White Paper – Sustainable development: The UK strategy(7)

1995 White Paper – Making waste work: A strategy for sustainable waste management in England and Wales(8).

• 1995: Environment Agency set up with the aim of achieving sustainabledevelopment.

• Various think tanks, consultative and instrumental bodies, such as theGovernment Panel on Sustainable Development, the UK Round Table onSustainable Development, ‘Going for Green’, and the Advisory Committee onBusiness and the Environment.

3.4 LegislationThe goal of sustainable development is addressed through a body of European and UKlegislation aimed at protecting the environment and through other legislationregulating such diverse sectors of the economy as planning, transport, energy, mineralsextraction, waste, leisure and agriculture. The main mechanisms are:

3 Sustainable development policies


• Proscriptive measures backed by criminal offences

• Economic instruments that either increase the cost of a potentially damagingdevelopment or reduce the cost of an environmentally friendly development

• Performance-based codes to encourage sustainable practices

The following are examples of UK legislation helping to promote sustainabledevelopment:

• Integrated Pollution Control of larger industrial concerns under theEnvironmental Protection Act 1990(EPA)(9). This controls emissions to air,water and land by requiring authorisation from the Environmental Agency.

• Controls on emissions to air under the Clean Air Act 1993(10)and emissions towater under the Water Resources Act 1991(11) and the Water Industry Act1991(12).

Clearly, it is important that all relevant legislation incorporates sensible engineeringstrategies.

3.4.1 PlanningThe Town and Country Planning Act 1990(13) requires that environmental impactassessments be carried out before planning permission is granted for developmentslikely to affect the environment.

Revisions to Planning Policy Guidance Notes and Mineral Policy Guidance Notes issuedby the Department of the Environment, now the DETR, since the 1992 Rio Summit takeaccount of environmental considerations, in particular PPG2 (Green Belt)(14), PPG6(Town Centres and Retail Development)(15) and PPG13 (Transport)(16). PPG12(17) containsa requirement for environmental appraisal of development plans.

3.4.2 EnergyThe Home Energy Conservation Act 1995(18) focuses attention on increasing energyefficiency in residential accommodation by requiring local housing authorities topublish reports identifying cost-effective energy conservation measures for localresidential accommodation.

3.4.3 WasteLegislation enacted to encourage sustainable waste management practices includes thefollowing.

• The EPA created a Waste Management Licensing Regime

• The Special Waste Regulations 1996(19) impose stricter obligations on producers,carriers and disposers of hazardous waste

• Landfill Tax increases the cost of disposing of waste by landfill

• The User Responsibility (Packaging Waste) Regulations 1997(20) put obligationson businesses handling at least 50t of packaging a year to ensure a proportion ofthe packaging waste is recycled or recovered. This encourages more sustainablemanagement of waste and should increase demand for operators specialising inrecovery or recycling of waste, so enabling them to provide those services morecheaply.


Chapter 4

Client and user requirements

IStructE Building for a sustainable future26

4.1 Sustainable constructionFor the client, the central thread of building development is to provide a viableinvestment with a healthy environment and to achieve environmental best practice forthe business and user activities. The First International Conference on SustainableConstruction(21) in Florida defined sustainable construction as ‘the creation andresponsible management of a healthy built environment based on resource-efficientand ecological principles’.

Balancing the concept of a viable investment with a commitment to environmentalbest practice means:

• Rapid, cost-effective solutions

• Effective management of the construction process

• Healthy buildings and internal environments

• Energy and water economy and waste management

• Materials and component selection for the required design life

• Planned operations and maintenance processes

• Sustainable development viewed as a collective responsibility

• Continuous improvement from a life-cycle assessment viewpoint

• Effective business management of environmental matters

• Use of suppliers with best environmental practice

This approach to development is summarised in BSRIA Environmental Code ofPractice for Buildings and their Services(22). Clearly, fiscal measures or marketencouragement to support better levels of initial performance would make the processeasier for clients and users.

4.2 Performance targetsBS EN ISO 14000(23) is a means to audit change and improvement. But there is still aclear need to define how to improve the goal of sustainability as part of a feasibleinvestment.

There is also a need for minimum performance specifications for buildings. Theseshould be simple to use and understand with clear implications of the sustainablevalues of the final product including effective operation and maintenance. In principle,for a given life cycle, targets should be based on embodied energy (GJ/m2)*, amaximum level of extractive material content (such as m3 of stone/m2) and amaximum non-renewable energy content per annum (kWh/m2). The selection ofmaterials to be used in a structure can have a significant effect on the environmentalassessment; it can be particularly beneficial if the materials/components have been re-used, or if the materials have been produced using recycled scrap.

These targets should be set to raise standards of operation above current expectations,particularly with a view to reducing the environmental impact of buildingdevelopment across the world.

4 Client and user requirements

*If the embodied energy for the complete building is expressed in GJ/m2 of floor area of the building, then theenvironmental assessments or targets for alternative forms of construction can be compared and considered on auniform basis.


There is also the need to assess, as well as measure, the potential flexibility of use of aproposed development for the future – by scenario planning – and the potential formaterial reuse and recycling. The same goes for effective operational maintenanceduring the life cycle.

In summary, a building development should use the minimum of material and energyand, in its making, cause less waste and achieve greater recovery to the environment.This should allow for ready operation and maintenance and easy replacement ofelements once their useful design life is exceeded.

Sustainable construction always requires an ethical stance and sometimes theconfidence to depart for the unusual.

Fig 8. Bedfont Lakes, developed by MEPC and IBM – a prefabricated steel structurewith precast slabs on a reclaimed landscape site


Chapter 5

Effects of building on theenvironment


5.1 Environmental burdenSustainability of development and of building activity is a global matter. Broadly, thetotal environmental burden (eb) of human activity is related to the population (p),affluence as a parameter for consumption (a), and technology (t). This may berepresented:

eb= f(p, a, t)

As eloquently described by Stuart Hart(24), the major challenge to sustainability of thebuilding activity as part of human activity in respect of pollution, depletion andpoverty differs among developed, emerging and survival economies (see Table 4).Engineers and others must therefore understand how their actions can have differingeffects according to the geographical context (see Table 5).

5.2 Assessment of global consequenceA formal environmental assessment of construction requires decisions during designon materials, components and the life-cycle implications. The decisions should takeinto account the environmental implications of winning materials, manufacturingcomponents and building with them. The subsequent operation of the structure andend-of-life decisions such as repair, refurbishment, demolition, reuse, recycling anddisposal also need to be considered. Any decisions should aim to minimiseenvironmental burdens under five ‘global consequences’, namely resource depletion,energy depletion, climate change, biodiversity and human health (see Table 5 and Fig 9).During the development, these burdens need to be considered in more detail under thenine themes (see glossary for details).

(1) Abiotic Depletion Potential (ADP)

(2) Energy Depletion Potential (EDP)

(3) Global Warming Potential (GWP)

(4) Ozone Depletion Potential (ODP)

(5) Ecotoxicity Aquatic/Terrestrial (ECA/ECT)

(6) Acidification Potential (AP)

(7) Human toxicity (HT)

(8) Photochemical Oxidant Creation Potential (POCP)

(9) Nutrification Potential (NP)

A formal assessment of all nine environmental themes cannot be carried out for everybuilding or structure. Instead, the extent will depend on the nature of the construction,its materials and their source, the amount and nature of transport required, the localmix of power generation, and legislative requirements. In general, impacts fall into thekey themes of depletion of resources, energy depletion, climate change or globalwarming, and biological diversity (see Table 5).

Within the building procurement and disposal process, all parties should be aware ofthe global consequence of their actions. These will differ for different stages in thebuilding life, as will interpretations between different professions.

5.3 Tasks for the development teamEach stage in the process contributes to the global consequence. To minimise globalburden, the structural engineer, as part of the total team, will need to evaluate the

5 Effects of building on theenvironment


Table 4 Challenges to sustainability

Pollution Depletion Poverty

Developedeconomies

Greenhouse gases Use of toxic materialsContaminated sites

Scarcity of materialsInsufficient reuse andrecycling

Unemployment

Emergingeconomies

Industrial emissions Contaminated waterLack of sewagetreatment

Overexploitation ofrenewable resourcesOveruse of water forirrigation

Migration to citiesLack of skilledworkersIncome inequality

Survivaleconomies

Dung and woodburningLack of sanitationEcosystem destroyedby development

Deforestation OvergrazingSoil loss

Population growthDislocationInstability

Table 5 Checklist of structural factors

Resource Energy Climate Bio-diversity Human health

C1 Nature ofstructuralsolution

Soil condition

C2A Materials, form Pre-assembly,material weight,form

Pre-assembly,material weight,form

C2B Adaptability,flexibility/elemental,standardisation

Surface treatment

C3 Durability,maintainability,standardisation

Surface treatment Ground water,durability

Ground water,durability,maintainability

C4 Use of primary/recycledmaterials,packaging,minimise waste

Degree ofprefabrication(linked tomanufacturer’slayer)

C5 Formwork/falsework,minimise waste

Mechanisationlevel

Contamination

C6 Extent of reuseAs-builtdocumentation

Extent of reuse

C7 Minimise waste


Fig

9. Im

pa

ct o

f d

esi

gn

de

cisi

on

s

Pla

nnin

gT

he S

iteA

rchi

tect

ure

Str

uctu

reB

uild

ing

Ser

vice

s/E

nviro

nmen

tal

Wat

er R

esou

rces

Mat

eria

lsM

inim

isin

g W

aste

Has

the

appr

opria

telo

catio

n fo

r th

ede

velo

pmen

t bee

nch

osen

?

Is p

lann

ing

perm

issi

on in

pla

ce?

Est

ablis

h th

at a

nyim

pose

d co

nditi

ons

can

be s

atis

fied

Are

ther

e le

gisl

atio

nis

sues

?

Is a

ny e

nviro

nmen

tal

audi

t req

uire

d?

Is a

ris

k as

sess

men

tne

cess

ary?

Is a

n en

viro

nmen

tal

impa

ct a

sses

smen

tre

quire

d?

Clie

nt r

equi

rem

ents

Is th

e si

teco

ntam

inat

ed?

Is th

e ow

ner

to b

ese

rved

with

are

med

iatio

n no

tice?

Has

the

site

inve

stig

atio

n be

enau

thor

ised

?

Car

ry o

ut r

isk

asse

ssm

ent &

circ

ulat

e to

all

part

ies

Has

a d

ecis

ion

topr

ocee

d be

en g

iven

?

Doe

s th

e se

lect

edm

etho

d of

rem

edia

tion

mee

t the

gui

ding

prin

cipl

es?

Hav

e ga

s ge

nera

tion

and

emis

sion

bee

nco

nsid

ered

?

Has

the

site

bee

nco

nsid

ered

for

gran

tai

d an

d la

ndfil

l tax

impl

icat

ion?

Has

the

conc

ept

desi

gn b

een

acce

pted

?

Has

tech

nolo

gybe

en u

sed

to e

nliv

ensp

irit?

Doe

s th

ear

chite

ctur

e pr

ovid

esh

ade

and

natu

ral

vent

ilatio

n?

Is th

e bu

ildin

gsu

bser

vien

t to

the

envi

ronm

ent?

Hav

e co

mfo

rt le

vels

and

the

dyna

mic

s of

hum

anoc

cupa

tion

been

cons

ider

ed?

Has

bui

ldin

gor

ient

atio

n be

enco

nsid

ered

?

Do

the

site

and

land

scap

e ac

hiev

evi

sual

har

mon

y an

dre

duce

impa

ct?

Is th

e qu

ality

of f

inis

hco

mpa

tible

with

long

life?

Has

the

stru

ctur

ebe

en d

esig

ned

for

natu

ral e

ffect

s?

Hav

e ad

apta

bilit

yan

d fle

xibi

lity

been

cons

ider

ed?

Has

the

cont

ribut

ion

ofth

e st

ruct

ure

to th

eth

erm

al e

nviro

nmen

tbe

en c

onsi

dere

d?

Con

side

r th

e lif

e of

the

stru

ctur

e in

term

s of

use

, reu

sean

d re

cycl

ing

Con

side

r se

lect

ion

optio

n fo

ras

sem

blie

s

Ass

ess

life

cycl

e an

dlik

ely

cost

s

Ana

lyse

ret

rosp

ectiv

ely

the

effe

cts

of th

est

ruct

ural

eng

inee

r'sde

cisi

ons

Take

into

acc

ount

effe

ct o

f pol

lutio

n,w

aste

and

ope

ratio

nen

ergy

Ana

lyse

eco

nom

icvi

abili

ty v

ersu

sen

viro

nmen

tal

sust

aina

bilit

y

Con

side

r C

O2

prod

uctio

n. I

s it

acce

ptab

le?

Con

side

r co

mfo

rtle

vels

Che

ck o

rient

atio

n of

build

ing

agai

nst h

eat

gain

/loss

Ass

ess

natu

ral

vent

ilatio

n ve

rsus

floor

dep

th

Is fa

bric

ther

mal

stor

age

and

CF

Dm

odel

ling

satis

fact

ory?

Hav

e en

ergy

targ

ets

been

met

e.g

.B

RE

EA

M?

Has

red

uctio

n of

prim

ary

dem

and

been

con

side

red?

Has

use

of g

rey

wat

er a

nd r

ecyc

ling

been

con

side

red?

Is s

epar

atio

nne

cess

ary?

Car

ry o

ut e

nerg

yau

dit f

or w

hole

life

of

build

ing

Cal

cula

te e

mbo

died

ener

gy in

act

ual

mat

eria

ls u

sed

inde

sign

Ass

ess

oper

atin

gen

ergy

and

aim

for

acce

ptab

le le

vels

Ass

ess

whe

ther

desi

gned

det

ails

are

com

patib

le w

ith lo

nglif

e

Ass

ess

long

life

desi

gn v

ersu

s ea

seof

dem

ount

abili

tyre

cycl

ing

and

reus

e

Set

up

proc

edur

e to

rem

ove

nuis

ance

of

was

te w

ater

run

off

and

dust

Iden

tify

mea

sure

s to

redu

ce n

uisa

nce

ofno

ise,

vib

ratio

n &

ecol

ess

Con

side

r ef

fect

s of

cons

truc

tion

and

oper

atio

n on

hea

lth

Con

side

r pa

ckag

ing

was

te v

ersu

slim

itatio

n of

dam

age

Und

erta

ke h

iera

rchy

exer

cise

to m

inim

ise

was

te

Doe

s th

esp

ecifi

catio

n pe

rmit

recy

clin

g te

mpo

rary

wor

ks?

Doe

s th

e co

ntra

ctco

ver

sort

ing

ofw

aste

by

cate

rgor

y?

Iden

tify

loca

tion

ofw

aste

sor

t

Dev

elop

men

t on

site

Yes

Yes

Yes

Yes

Yes

No

impact of engineering decisions on the entire process of building activity, constructionand occupation.

For the structural engineer or other specialists, specific impacts on burden should beindicated against current and likely future environmental concerns and clientperceptions. Considerations such as current and life-cycle costing and legislativerequirements – e.g. taxes (on landfill, energy and carbon), eco-labelling, end-of-lifematerials, and ‘polluter pays’ principles – should be included.

Fig 9 identifies some of the items the development team, among them the structuralengineer, will need to evaluate through the stages of the development process inrelation to global consequence. To do this effectively, structural engineering educationneeds to include instruction on the ecological workings of the planet (see Fig 1). Sucheducation will help future generations of engineers prepare route maps on the likelyenvironmental outcome of material selection, the construction system, and the processfrom cradle to grave.

5.4 Specific tasks for the engineerThe main issues that need to be addressed by measurement (quantification) andassessment (qualification) are shown in Table 6 overleaf.

Some of the tasks which the structural engineer – together with other disciplines ofarchitect, planner, constructor and user – needs to address are:

• Minimise disposal of soil offsite

• Standardise formwork designs and allow for formwork reuse

• Focus design loads as just adequate for proposed use (including seismic,typhoon and groundwater effects) and evaluate for proposed life of built form

• After careful study of present and future uses, do not overdesign the structure‘just in case’

• Assess the implications of design life (remember that design life is theoretical,service life is reality)

• Choose a structural system capable of being reused or recycled elsewhere

• Investigate the possibilities of structural determinacy to simplify prefabricationand future reuse as against the economies made possible by structuralredundancy and structural continuity

• Carefully consider the effects of jointing

• Where feasible and appropriate, incorporate recycled materials, reused elementsand the products of demolition into new build

• Choose a simple structural grid with an eye to low initial cost and minimumembodied energy

• Consider adaptability for future use and adequacy for alternative uses

• Make sure calculations, drawings and records are available on disk and in hardcopy to facilitate reuse, adaptation and efficient demolition in the future. Theseshould become part of the documentation of ownership

• Use prefabrication as a way of reducing waste on site and as a device forrecycling waste in manufacture at source

• Choose structural materials and systems with a view to reasonable embodiedenergy. For example, a structural solution requiring twice the volume ofstructural material than an alternative, simpler solution will double the resourceand energy load on the planet

• Design joints for dismantling, demolition and reuse as well as ease ofconstruction assembly


• Require constructors to produce an environmental and waste managementstatement with tenders

• Schematic designs that are to be developed for construction by the contractor onthe basis of performance criteria should include specific limits on operationalenergy (kWh/m2 year), embodied energy (GJ/m2), and maximum uptake of newmaterial (m3 aggregate)

• Ensure users update building records as modifications are undertaken

• Design so that as many of the elements as possible are suitable for adaptation toalternative uses in the future.


Table 6 Issues for sustainable development

1. Appropriate location fordevelopment

Minimisation of environmental and civic costs ofgetting thereSynergy within townsSelf-sustainability, particularly in rural situationsSynergy of development to existing infrastructure

2. Choice of built form

Wall-to-floor ratios, robustness versusrecycleability and ‘determinacy’Contribution of building fabric to internalenvironment by thermal mass, admittance andcontrol of natural lightApproach to consumption and recycling of waterFlexibility versus adaptability

3. Choice of structural material

Control and evaluation of embodied energy/m2

over the life of buildingEase of refurbishmentPossibilities for recycling

4. Minimising the effects ofconstruction and deconstruction

Landtake, reuse of contaminated landMinimisation of waste and byproductsAbility to reuse materials in future construction


Chapter 6

Adaptability and flexibility


6.1 Long life, loose fit, low energyThe extent of re-use within buildings is considerably greater than that of the buildingstock itself. An ordered response to the 1994 framework, Sustainable Development ofthe UK(7), could therefore be:

• Refurbish, adapt and reuse existing buildings

• Design and construct new buildings that are adaptable to different uses andtherefore offer longer life

• Use recycled components and materials or those from sustainable sources

• Minimise energy needed to operate a building by essentially passive design

• Use or recycle waste produced during construction operation and deconstruction

In short, the best response to the different levels of change is to use the approachoffered 28 years ago by RIBA President Alex Gordon of ‘long life, loose fit, lowenergy, (LL, LF, LE)’(25). Recognition of these different rates of change requires thedesign process to differentiate between flexibility and adaptability in buildings.Flexibility is the capacity of a building or elements of a building to be physicallyrearranged. Of course, some elements of a building – primarily the structural elements– are inherently inflexible. Adaptability is the capacity of a building or elements of abuilding to accommodate changes of use or occupation. Such capacity depends largelyon the choice of structural grid and the range of loads the resulting structure cansupport.

6 Adaptability and flexibility

(a) Exposed core of structure beforerefurbishment

(b) Following completion

Fig 10. Winterton House – an example of substantial refurbishment


To increase the potential sustainability of use, the client and the design team led by thestructural engineer should think about ways of increasing future adaptability. This canbe done by providing spare load capacity (i.e. greater than that needed for theimmediate use), by structural redundancy (which might make future modificationseasier), or by designing on a larger structural grid (to allow for other uses).

For greater sustainability, the associated first costs of these possibilities should then beinvestigated at the conceptual stage in relation to the total development cost. The valueof the development can then be compared with the likely additional cost of lateradaptation to alternative use.

6.2 Inherently inflexible aspectsFor the structural engineer, the inherently inflexible aspects of a primary structure arecandidates for this investigative approach. These are:

• Location on the site

• Primary load-carrying structure

• Ground-floor slab

• Underground drainage

• Foundations

The primary structure for horizontal and vertical loads can be changed by competentappraisal, reassessment and the addition of structural elements supporting alternativeload paths required for a reuse. Reference can be made to the Institution of StructuralEngineers’ report Appraisal of existing structures(26).

Other elements such as roof form and roof drainage, the vertical circulation core, andzones for primary vertical and horizontal services distribution are also often part of theprimary concept for a building and so can present a problem later when the use ischanged.

In this way, the structural engineer can contribute significantly to improving benefitfrom the investment in such elements over the working life of the building withoutsubstantial additional first cost. Such an approach can usefully be co-ordinated toconsiderations of standardisation and/or pre-assembly for the structure and of otherconstructive elements as cladding, bathroom units, and mechanical equipment thatmight be supported by the structure.

Following the LL, LF, LE principle of design and those of sustainability, the primarystructure should possess its own lateral stability and not depend on the strength ofsubsequent construction elements such as cladding or internal walls that may bereplaced in a subsequent use.

Human activities are inherently adaptable to the space available. At the room scale,such spaces do not have to be tailored exactly to the activities within them. This isespecially important in selecting the layout of structure to give flexibility of partitionsand allow for present and future access routes and ducting so as not to inhibit reuse ofa building by a later occupier. The structural engineer should therefore aim to makethe frame as simple as possible, so that walls can be moved and floor layouts changedwithout detriment to the building’s stability.

By providing a suitable (not absurd) redundancy in some or all of the frame elements– and particularly those designed by structural engineers – a much longer useful life ispossible from the building, and hence from the materials and components. In otherwords, one way of producing a sustainable development is to demonstrate to buildingowners and users the advantages of such choices. This takes design time and resourcesbut can be worthwhile in terms of the benefits to the client and, by implication, theirsuccessors.

6.3 Keeping adequate recordsAlthough it is difficult to foresee the way buildings may need to be changed, theyshould be capable of being adapted to alternative uses in the future. This appliesparticularly to the structural frame. For example, upper floors and/or the roof shouldbe carried to ground as simply as possible so that the route will be obvious to anyonealtering the building for reuse. The changes may often be in a way the originaldesigner had not considered and small alterations can sometimes cause more problemsthan larger ones.

Adequate records must be kept, preferably in more than one location, and should bereadily available when altering or changing the use of a building. The records shouldinclude a complete set of calculations, drawings, details of materials such as sourcesof bricks and details of timber, and the names of major subcontractors as well as allmain contractors and the design team. At least one set should form part of an operationand maintenance manual held by the building owner. A further set should be held withthe deeds to be passed on each time the building changes hands. This document couldbe duplicated on microfiche or held on CD-ROM. Furthermore, the manual should beupdated whenever there is a major alteration. Much of the same information isrequired for the Health and Safety File under the Construction (Design andMangement) Regulations 1994(27).

Calculations should be set out in a logical order and include a cover sheet detailingsources of references, including Standards and Building Regulations, design loads andassumptions (particularly for foundation design) and the characteristic design stressesof the materials, with some idea where they have been used. There should be astructural summary setting out the principles of the structural design, including howstability is provided. For buildings larger than a small domestic extension, an index orcontents list should be included. The calculations should be accompanied by plenty ofkey plans and sketches indicating the designer’s intent.



Chapter 7

Materials


7.1 BackgroundMaterials for construction tend to be selected early in the procurement process. Thechoice should be made not just on the basis of cost but also the likely environmentalburden caused by their extraction, manufacture and use. Generally, non-renewablematerials cause environmental damage in the following areas:

• Amount of fossil fuel consumed in the making of a product

• Pollution of the environment by production, use and disposal

• Consumption of non-renewable resources

The flow process for materials is illustrated in Fig 11. The materials used in thebuilding process can be categorised:

• Metals Ferrous

Non-ferrous (Al, Cu Pb, Zn, Sn)

• Concrete(s) Dense, lean mix, lightweight, air-entrained

• Timber Hardwood

Softwood

• Masonry Brickwork, blockwork, other

Natural stone

• Surface protection systems Paints, galvanising, non-rusting

• Glass

• Composites Rubbers, plastics, fibres, foams

• Extracted materials Sand, gravel, aggregate, crushed rock

Another approach to categorisation is that a building development is procured andmade up of parts – foundations, structural elements, envelope (cladding, glazing,roofing and insulation), surface finishes, electrical, mechanical and water systems –and then fitted out and occupied by human and botanical species. Specific design lives(to refurbishment and replacement) are needed for each of these parts if the cradle-to-grave burden is to be accounted and minimised. Two useful references have beenpublished recently by BRE relating to the selection of construction materials andcomponents from an environmental viewpoint. They are BRE methodology forenvironmental profiles of construction materials, components and buildings(28), andThe Green Guide to Specification(29).

7.2 Embodied energy and operational energyBefore actual burdens can be studied, the ‘embodied energy’ of the building activitymust be quantified. This is defined as the total primary energy that has to besequestered from a stock within the earth to produce a specific product or service. Bycommon consent, the embodied energy in a building is modest in relation to thequantity of energy it consumes during its life(30, 31, 32, 33, 34). Furthermore, research isstarting to show that – provided ‘sensible’ engineering devices and clear load pathswhich follow the basic laws of physics are employed – embodied energy varies littlebetween different structural solutions. For buildings up to six storeys or so, theembodied energy is 2.5–3.0GJ/m2, increasing in unusual circumstances to 5GJ/m2.This represents only some 10% of the total target energy profile required for a 60-yearbuilding life (60GJ/m2) – see Fig 12.

7 Materials


Was

te

Was

te

Was

te

Was

te

Dis

posa

lR

aw m

ater

ials

(bio

tic &

abi

otic

)as

sol

id, l

iqui

d or

gas

Rec

over

y an

dre

finer

y

C4

Man

ufac

ture

syst

ems

and

com

pone

nts

C5-

Con

stru

ct,

Ass

embl

e

C6-

Fac

ility

man

agem

ent

and

use

Inse

rt n

ewm

ater

ial

Rem

ove

old

mat

eria

l

Rec

ycle

old

mat

eria

l?

Rec

ycle

old

mat

eria

l?

Rem

ove

old

mat

eria

l

Inse

rt n

ewm

ater

ial

Rec

ycle

old

mat

eria

l?

Reu

seco

mpo

nent

s?

Rep

lace

?

Dem

olis

hD

ism

antle

Ref

urbi

sh?

Rep

air

?R

etai

n?

C7-

End

of l

ifeE

valu

atio

n

CO

-Pro

ject

eva

luat

ion

C1-

Site

Eva

luat

ion

C2,

C3-

Con

cept

and

det

aile

d de

sign

Dis

pose

to la

nd, w

ater

or

air

Y

NY

NY

N

Y

N

Y

NN

NN

YY

Y Reu

se

Not

e1. E

nerg

y is

req

uire

d at

all

stag

es.T

rans

port

atio

n bu

rden

s al

so h

ave

to b

e co

nsid

ered

at a

ll st

ages

Not

e 2.

"E

nd o

f life

" in

clud

es m

any

"end

of p

hase

" ev

alua

tions

.

Fig

11

. F

low

of m

ate

ria

ls

Much information is available on the energy used to heat, light and ventilate buildingsbut little exists on the energy required to produce, transport and maintain constructionmaterials and products. The proportion of energy that is ‘embodied’ or ‘operational’varies between building types, as illustrated conceptually in Fig 13. The extremes areperhaps a bridge, with high embodied energy and low operational requirements, and ahospital, where the operational energy is high.


Structural Frame and Floors

Rest of the Structure

Lifetime Additions

Lights and Small Power

Heating and Ventilation

30

25

20

15

10

5

0

Ene

rgy

(GJ/

m2 )

Energy consumption (60-year life)

Energy table for design life of building

70

60

50

40

30

20

0

Ene

rgy

(GJ/

m2 )

10

0 10 20 30 40 50 60 yrs

Overall energy-H&V

Overall energy-Lights

External envelope-Rest

External envelope-Structure *

*

*

* denote lifetime additions

Fig 12. Energy contributions to life cycle for a typical office

EMBODIEDENERGY 'Bridge'

Temperate

Warm/Humid

Differentclimates

Hospital

EMBODIED ENERGYInitial burden

Operational burden

Offi

ce

Hos

pita

l

Brid

ge

OPERATIONAL ENERGY

Fig 13. Energy profiles


Fig 14. Iron ore extraction, Western Australia

Fig 15. Timber transportation in Canada

According to the Building Research Establishment, building production in the UKaccounts for about 8% of all carbon dioxide emissions, while the energy used inrunning buildings is responsible for 50%: in 1990 this amounted to 579 milliontonnes.

7.3 Direct and indirect environmental effectsThe environmental burden is reduced by making sure that buildings and otherstructures have as low embodied energy and embodied carbon dioxide as possible.The basis for reduction should be:

• Comparisons between products with the same function and between options forthe same element or component

• Embodied energy taken as the gross primary fuels extracted from resourcestocks taking account of the whole life of a material within a building

• Thermal capacity

Other indirect environmental issues associated with this process are listed in Table 7.

7.4 Ecological properties of materialsFor structural engineering, two material properties are of primary importance –modulus of elasticity and strength. In addition, density, thermal expansion, durability,dimensional stability with time and ease of jointing need to be considered. Materialsare rated according to their lifetime cost in terms of initial cost of production (£/tonne,£/m3) and the costs of energy, labour, transport, etc. which together make up the total.To identify the environmental burden, materials need to be rated in terms of the cost ofproducing one unit of usable property (£/unit of modulus of elasticity).


Table 7 Other environmental issues

Stage Possible environmental issues

Extraction of raw materialsEcosystem loss, finite resource loss, amenity loss,noise, dust, hydrogeological effects, transport,infrastructure effects

ManufactureEnergy consumption, finite resource loss, air andwater pollution, noise, dust, effects on ecosystems,global warming, acid gas emissions

DistributionEnergy consumption, noise, dust, global warming,acid gas emissions

ConstructionNoise, dust, air and water pollution, emission ofhazardous substances, effects on ecosystems,packaging, waste minimisation, construction

Building in use

Energy consumption, durability, maintenancerequirements, replacement frequency, ease ofreplacement, global warming, acid gas emissions,waste water

Demolition and recyclingNoise, dust, reuse, contamination of soil, energyconsumption, global warming, acid gas emissions

The most convenient starting point in designing for minimum embodied energy use isto design for minimum weight since transport and erection cost are weight-dependentand both consume energy. Minimum weight design – which is the basis of muchprofessional engineering practice – can be thought of as answering the question ‘Howmuch material is needed, measured in terms of the quantity of energy for the necessarystructural material, to support a unit area of use (kJ/kg of material/m2 of floor area)?’

The primary requirement for minimising environmental burden is therefore met byengineers, and others, designing and building on the basis of established goodpractice, i.e. complying with the laws of mathematics, of physics of stress underdeflection, and of fluid, thermal and radiation flow.

Essentially, embodied energy consumption is minimised by designing for minimum


Fig 17. Transportation of prefabricated construction materials

Fig 16. Sustainability in forests, British Columbia, Canada

weight, with materials arranged in terms of the energy required to produce thatstructure. Such an approach requires the following to be fixed at the design stage indiscussion with the client and user:

• Required design life

• Size of the working load

• Distance over which the load must be carried

• Definition of failure in service

• Whether elements are designed to stress and/or deflection limits

Therefore, both environmental burden and total cost may be reduced by ensuring thatthe building adheres to performance-based standards and codes of practice rather thanprescriptive requirements.

Appendix A illustrates some earlier approaches to the parametric analysis of the costto the environment arising from use of materials. Research using such parametricanalysis may in due course define materials whose manufacturing charge in energy


Fig 18. British Steel Teeside Works, Redcar: an example of an integrated steelworkswhere particular attention has been paid to local environmental issues

terms can be minimised. A philosophy exists but not yet a design guide and furtherbasic research is needed. More recent developmental work on such parametric analysiscan be obtained from sources such as BRE’s Centre for Sustainable Construction.

7.5 SummaryTo be cost-effective and to achieve greater environmental sustainability, life-cyclecosting (LCC) (see Appendix B)must be carried out in parallel with a life-cycleassessment (LCA). Environmental impact assessment is not an exact science.However, a formal qualitative statement may be used to establish a ‘plateau’ forvarious building activities where the environmental burden is acceptably small – seealso Fig 6. To do this, all participants need to understand the process of life-cycleassessment, remembering that:

• Buildings should be designed to answer an identified focused need, and shouldbe standardised to some degree

• Buildings provide a protective environment constrained by the laws of physicsinto which the minimum levels of non-replaceable material and energy arerequired for an acceptable lifetime

• Building is essentially an assembly industry that should use the minimumquantities of ‘audited’ prefabricated components (bricks or bathrooms) andassemble them with the least waste and damage

• From the viewpoint of sustainability, decommissioning and demolition may beas significant as the initial construction



Chapter 8

Designing for sustainable occupancyof a construction


Correct orientation of the primary façade would suggest that commercial buildingswith potential for over-heating should be oriented with their primary façade north-south. For a domestic development, east-west orientation of the primary façade isgenerally best for passive heat collection and living patterns. The use of an east andwest facing façade for commercial developments requires careful consideration.

For success, the façade needs to be protected against the impact of high-energy, low-angle sunlight and may require a dynamic shading system. The design of a shadingsystem is a highly iterative process as it must balance shade, daylight and glare.

Low-energy, naturally ventilated buildings perform satisfactorily with a solid/glassratio of about 50/50, the solid element being highly insulated and having adequatethermal capacity.

The future lies with ‘intelligent’ façades, where the word ‘intelligent’ suggests the useof self-regulating thermal protection and solar control to adapt in a dynamic way to thechanging external climate. The use of photochromic glass is one such an example.

8.5 Comfort cooling and air conditioningBuildings often need to be designed with temperature-controlled ‘comfort cooling’.Alternatively, they need to be fully air-conditioned, with both humidity andtemperature controlled. In temperate climates such as in the UK, air conditioningshould be confined to locations where the external environment is hostile (noisy orpolluted) or where there are exceptional internal heat sources (e.g. high IT load). Indesert or tropical climates, air conditioning may be necessary. But even hererestricting energy gain – by using reflective glass, passive shading and thermalcapacity – can help towards a more sustainable development.

8.6 Natural ventilationA growing number of buildings are being constructed to provide a workingenvironment employing natural ventilation or a ‘mixed-mode’ solution using acombination of natural ventilation, mechanical ventilation and comfort cooling. Theperformance of a mechanically cooled building is judged by the internal temperature,humidity, and air-change rates achieved. But, in a naturally ventilated building, abroader range of temperatures and humidities must usually be accepted. For example,

Fig 19. Façade of Open University building with façade as moderator for naturalventilation and light, structure as thermal mass –

construction management for minimal waste


8.1 Operational energyAs described in Chapter 2, designing buildings for lower energy consumptiondemands a holistic approach. The structural engineer can play an important role in thisalongside the architect, building services engineer and other professionals.

The energy consumed in buildings by heating, ventilation (and air conditioning),artificial lighting and by office, catering and other equipment greatly exceeds theenergy consumed in construction and demolition. The amounts of primary energyneeded for different options should be defined early in the design by the services andenvironmental engineer. The structural engineer can help to establish the differentoptions arising from location and choice of built form.

8.2 Designing for comfortTo achieve greater environmental sustainability of the built environment, the quantityof primary energy used to create a habitable environment must be reduced. To do this,the prescriptive criteria of precise temperature and humidity requirements favoured bythe majority of institutional investors must be abandoned. Instead, criteria thatrecognise the tolerance and range of comfort acceptable to most occupiers and formost uses should be adopted.

There are applications – such as museums, clean operational facilities in industry, andparts of hospitals – where prescriptive control of temperature, air quality and humidityis necessary. However, most human occupation can now be precisely defined to becomfortable within an envelope of visual, acoustic, thermal, air quality, psychologicaland clothing criteria. The individual criteria can vary while the total environmentremains comfortable. This flexibility is the very essence of establishing theopportunities for passive design of the built environment necessary for greaterenvironmental sustainability.

8.3 Insulation and infiltrationMost building designers are aware of the benefits of providing thermal insulation andof the minimum requirements set out in the Building Regulations. Improvements ininsulation in recent years have meant that heating loads due to air infiltration nowform a more significant proportion of the total. These infiltration losses should bereduced to the minima required for occupation. To achieve target criteria, buildingsshould ideally be pressure-tested to check their performance. Specialised façadeengineers can help establish good design practice, test cladding components andmonitor installations. Reference should be made to the Institution of StructuralEngineers’ report Aspects of cladding(35). In countries where such infiltration controlhas been adopted, construction standards have been generally improved and energyconsumption reduced.

In designing a well sealed building, careful attention must be given to indoor airquality in winter. Controllable ventilation strategies should be provided that producedraught-free ventilation without excessive energy demand. The maxim should be‘build tight – ventilate right’.

8.4 The façade as climate moderatorThe façade is the first line of defence against the impact of the external climate on theindoor environment. It can usefully be considered as part of the building’senvironmental system. Its performance, both static (insulative) and dynamic (light andair), interacts with the building energy systems. The result should be a comfortable,controlled and efficient solution. Heating and cooling systems should never be thoughtof as add-ons after the building has been designed.

8 Designing for sustainableoccupancy of a construction

performance may be defined at the design stage in terms of the number of workinghours per year that a particular temperature, say 25°C, might be exceeded. Computerprograms using dynamic thermal models can be used to predict the performance ofparticular buildings based upon weather data and real thermal response of the buildingfabric, air-change rates, admittances and heat sources.


Fig 20. Headquarters building for RWE, Essen: triple-glazed façadeon a reclaimed site

8.7 Passive design of buildingsSuccessful naturally ventilated and naturally lighted buildings rely on a large numberof factors. The structural engineer can contribute towards establishing some of theseduring design. Guidance is provided by the CIBSE report Natural ventilation in non-domestic buildings(36). As an initial check list, some of the following criteria may beappropriate in establishing effective passive design:

• The shape and orientation of the building

• The local climate and adjacent landscaping

• The width of floor plates

• Whether spaces are to be open plan or cellular

• The balance between the provision of daylight (to avoid artificial lighting) andsolar gains

• Well-designed windows that allow adequate ventilation without creatingdraughts. The ventilation may be created by the ‘stack effect’ (cool air enteringat low level and warm air exiting at high level) or by ‘cross ventilation’ fromwind effects

• Exposing the fabric of the building by avoiding the use of surface finishes thatare intrinsically insulating such as lightweight plaster, false ceilings and noticeboards. Exposure of the structure allows it readily to absorb heat during the dayand release it at night. The cooler surfaces can also make the occupants feelmore comfortable despite a warm air temperature. This is why building servicesengineers do not design to achieve a particular air temperature but instead a‘resultant’ temperature that takes account of radiant heat and air movement

• Exposed construction can be made more effective by the incorporation ofextended surfaces, such as a wave-form soffit. High-quality surface finishes andjointing may be required to make the results aesthetically acceptable and toincrease reflection of light. An alternative, especially in existing buildings, islouvered ceilings

• Exploitation of thermal capacity at floor level is more difficult because offurniture and floor finishes. Raised floors offer one solution that may overcomethis problem by allowing ventilation air contact with the slab before beingintroduced into the room through floor diffusers. The void can also be used forelectrical and IT services. As the natural driving forces from stack effect for theventilation air are limited, the space must not become too congested

• Passive summer cooling can be made more effective by solutions such as solarchimneys (to increase stack ventilation), by wind towers, or by ventilating thestructure itself by using hollow slabs (proprietary systems are available) orductwork

• Use of alternative forms of cooling, such as ground water

• Use of automatic or manually-controlled windows or other ventilation devices torelease heat collected in the structure during the day when the outsidetemperature is lower at night

• Where the building is in a hostile location, say next to a busy road, it may bepossible to duct air from a cleaner side of the building or central courtyard

• In applying these approaches, the potential for acoustic problems due to theexposed hard surfaces or open windows and for security questions at night needto be considered.

• Initial occupants and new staff of the building will need briefing on how thesystem works and how to operate it to best effect


• In the spirit of providing a ‘loose-fit’ building, consideration should be given towhether a fully passive approach will limit the building’s future use. Flexibilitymay be increased, for example, by providing space for mechanical systems to beadded, modified or removed

• Apart from passive approaches to reducing energy in buildings, there aremechanical options that may influence a sustainable building design. Forexample, a small and efficient water chiller run at night may store cooling in theform of ice. Although the chiller and associated plant may be small, the icestorage itself may be bulky and heavy

• Combined heat and power systems may eliminate the need for boiler and evenchiller plant in buildings


(b) Naturally lit finished interior

(a) Virtual prototyping for prefabricated parts

Fig 21. The new environmentally-friendly building at BRE


Chapter 9

Water use and water saving


9.1 IntroductionHistorically, water in the UK has been a plentiful resource, free to the user, and littleregard has been given to economy of use. Elsewhere in the world, this is not so.However, over the past few years, there has been a drastic change in rainfall patternseven within the UK. Most regions have witnessed hotter, drier summers andsignificantly reduced rainfall during the traditionally wetter winter months.

Although 70% of the surface of the planet is composed of water, less than 1% of thiswater is in a fresh potable state. Most is held within the oceans and makes its way tothe land as precipitation. This precipitation in turn either makes its way back to the seaas surface water or percolates down as ground water. This ‘hydrological cycle’ (seeFig 22) dictates the amount of water available to a population.

The rainfall intensity over a given land mass is a measure of the sustainablepopulation that land mass can support. Countries receiving less than 1 700m3/personeach year are described as water stressed. The situation becomes critical if the figurefalls to 1 000m3/person. Potable water supplies need to be protected against loss andthe effects of pollution, especially in those countries that can least afford to lose them.

In addition to the amount of water a country receives, the quality of that water is alsoimportant. It is therefore necessary to protect the quality of any potential potablesupplies by excluding harmful domestic or industrial discharges into them. Manypotable supplies have been lost to pollution, often in countries that can least afford tolose them.

It is estimated that each person requires about 50 litres of water each day to maintain ahealthy life. This figure includes water for drinking, washing and bathing. Actualwater use in developed countries is far higher than this and is dictated very much bylifestyle. Labour-saving devices such as washing machines and dishwashers andactivities like gardening are very water-intensive. Thus, in the UK, water consumptionper person is about 180 litres/day and in the US around 400 litres/day. But such figures

9 Water use and water saving

Infiltration

Surfacerunoff

Spring River Lake

(GWT) (GWT)

Ground water

PERCOLATION

Rainclouds Cloud

formation

Transpirationfrom plants

Evaporationfrom land and water

Swamp Ocean

Ground water table (GWT)

PrecipitationSnow

Fig 22. The hydrological cycle


pale compared to the amount of water used by industry. Construction materials such assteel and concrete have extremely high water requirements for their manufacture,although in some industries, such as steel manufacture, most of the water is repeatedlyrecycled in closed-loop systems. The amount of water used by a range of devices suchas toilets and baths, is slight compared to the huge water consumption ofmanufacturing and materials industry.

9.2 Industrial water-saving optionsPotentially the most dramatic reductions in water use can be made by industry. Manyindustries in the UK are now making serious attempts to limit the amount of waterthey use in manufacturing by a process of environmental audit and wasteminimisation. If high consumption continues, water companies may not be able toguarantee continuity of their supply through a dry summer.

Two demonstration case studies – the Aire and Calder Project and the River DeeProject – were co-ordinated in the UK by the Environment Agency. Bothdemonstrated major savings in water use and cost. For instance, Coca-Cola reported asaving of £1.6 million and British Rail £290 000. Lower water use can be encouragedby purchasers within the construction industry insisting that all suppliers have:

• an effective environmental management system

• carried out environmental audits, and

• waste water minimisation strategies.

9.3 Commercial and domestic water economyEngineers are likely to be able to bring about the greatest water saving in thecommercial and domestic sector. There are a number of ways in which major watersavings can be made in the design and specification of new buildings:

• Use of construction materials that are water-efficient in their manufacture

• Incorporating rainwater collection and storage devices, such as undergroundtanks beneath the garden, into the design

• Use of recycled ‘grey water’ – e.g. water already used for washing – in largercommercial developments

• Specification of low flush sanitary fittings and water-saving devices

The technology of designing water-efficient buildings is similar to that of energy-efficient buildings in the early 1970s. Buildings that do not require mains water butinstead recycle water and harvest rainwater have been designed and built. An award-winning, so-called ‘water autonomous’, house was built in Nottinghamshire byArchitects Robert and Brenda Vale in 1993(37) incorporating such features.

The simplest way of saving water in a building development is to collect rainwaterfrom the roof and store it, normally in the basement. After simple filtration, it can thenbe used for various non-potable uses such as flushing toilets, watering the garden orwashing the car. The storage area required is likely to be small and is easily calculated.

However, the largest potential for saving water in commercial and domestic propertiesis to reuse the discharge from baths, showers and laundry facilities. This ‘grey water’is not to be confused with ‘black water’ which is water contaminated by faecalmaterial. Owing to the risk of pathogenic infection, it is impracticable to use blackwater other than on an experimental scale. Black water is best disposed of direct to asewer and, by using low flush toilets, with a much reduced volume. Grey water can betreated easily if there is enough land requiring irrigation. Thus, grey water reuse isfeasible for facilities such as hotels, country clubs, golf courses and tennis courts,outdoor pursuit centres and field centres or any development adjoining agriculturalland.

Grey water can be treated in a lagoon system resembling a series of natural lakes that

hold the water for about 30 days to allow treatment to be completed. Alternatively itcan be treated in a natural system planted with rooted aquatic plants that removeimpurities. In either case, the treatment facility can form an attractive landscapefeature. The treated water then requires storage, again in a natural lake, from where itcan be extracted for irrigation.


Fig 23. Treatment lagoons for grey water

Fig 23 illustrates such a scheme in operation at a residential country house with a largegolf course. The treatment lagoons are sited around the golf course and act as waterobstacles, the final treated water being used for watering the greens.

A wide range of sanitary fittings is available to reduce water consumption. Many, suchas the dual flush and low flush toilet, are routinely specified and widely accepted. Inaddition, simple but extremely effective pressure/flow reduction devices can beobtained that reduce water use by up to 20%.

9.4 Future developmentsOne current major research initiative is aimed at identifying options for saving andrecycling water, focusing largely on black water. This area is always likely to becontroversial because of its inherent aesthetics and the health problems associatedwith faecal material. Nevertheless, as the flush toilet is responsible for 30% of allhousehold water use, any developments that lead to savings are to be welcomed. Twomajor approaches are under development. The first envisages a wider use of drycomposting toilets. These mix the organic waste with sawdust which drops to anunderground reactor where decomposition occurs. The process generates heat whichcan be recovered. The second approach combines treatment of grey and black water ina compact unit suitable for building developments where lack of land rules out lagoonsystems. It exploits new developments in membrane technology that permit liquids ofa high solids content to pass through membranes with pore sizes as low as 9.25µm.Such a membrane is able to remove all the bacterial and protozoan pathogens as wellas many viruses. The treated water is then used for flushing toilets and for wateringgardens. Because of the potential for disease transmission, the system requiresseparate plumbing and the water is usually chlorinated and dyed so that it is notmistaken for a potable supply. A typical plumbing arrangement for combined grey andblack water treatment in commercial property is illustrated in Fig 24.


Tanks Tanks

Wastewater Wastewater treatment plant

Wastewater Pump

Secondary treatment facilityAdvanced treatment facility

Discharge

Tank

Pump

Reclaimed water

Conveyance pipe

Distribution basin

Distribution facility

Distribution pump

Distribution pipe

Water recycling centre

Machinery and electric installationPumpPotable water

washinghands

Flushtoilet

customers

Disinfection

Reclaimed water

reclaimed waterPotable waterTanks

Fig 24. A typical plumbing arrangement for combined grey and black water treatmentin commercial property


Chapter 10

Contaminated land as a resource


Current Government policy in Europe and the USA is to undertake a risk assessmentof contaminated land as part of determining its potential for development. Riskassessment should be carried out together with a site investigation to help select usefulmethods of site treatment and the early development of the remedial strategy so thatthe site may be reused appropriately.

10.1 ContaminationSite contamination occurs as a legacy of both historic and current industrial and otherprocesses. Refuse from these processes and from the tipping of domestic waste and thestorage of chemicals may be present. In some cases, methane and other gases may beproduced by decomposition.

The internationally recognised definition of contaminated land as drawn up by theNATO Committee on Challenges to Modern Society (CCMS)(38) is: ‘Land thatcontains substances which, when present in sufficient quantities or concentrations, arelikely to cause harm directly or indirectly to man, to the environment, or on occasionsto other targets’.

Sites where contamination might be expected include – but are not necessarily limitedto – the legacy from:

• Processing or manufacture of products containing asbestos

• Chemical plants and depots

• Docks

• Explosive factories

• Gas works

• Landfill sites

• Metal smelting, refining, treatment and finishing works

• Mines and quarries

• Oil production and storage

• Paint depots

• Railway yards

• Scrap yards

• Sewage works

• Steel works

• Farming

10.2 Site investigationThe site investigation provides the basis for all decisions and action. It is therefore animportant part of the risk management of contaminated land. The engineer needs tomake a preliminary appraisal of the site, sometimes before it is purchased by theclient, to identify the nature and general location of any contamination. Thispreliminary appraisal should involve as few people as possible to minimise exposureto potential hazards. It usually takes the form of a desk study and site reconnaissance.The desk study will normally provide information on any health and safetyprecautions necessary for persons entering the site.

10 Contaminated land as a resource


A detailed site investigation should provide quantitative data and include an analyticalstudy in enough detail to permit decisions on feasible financial and technical options.Care is required in planning the investigation to make sure site procedures do notinadvertently have a detrimental effect on the environment, e.g. contamination of anaquifer by sinking a borehole through contaminated land.

Site investigations for pollution and the preparation of reports on contaminationshould be undertaken by qualified persons experienced in this discipline.

10.3 Risk assessmentRisk assessment is that part of risk management that appraises the significance ofobserved levels of contamination on site. More specifically, a risk assessment shouldaim to determine whether:

• Observed site contamination is likely to present unacceptable risks to probabletargets now or later

• Measures are necessary to reduce risks to acceptable levels

Generally, there are two approaches to the presentation of risk assessments:

• By comparing levels of contamination on site with reference data such as thatprovided in guidance notes(39) from the Interdepartmental Committee on theRedevelopment of Contaminated Land (ICRCL)

• By making qualitative or quantitative risk estimates

Risk assessment information should be communicated to all interested parties,including local authorities, not just to the design team.

10.4 Trigger concentration levelsICRCL trigger concentration values are set out in the relevant guidelines to aidassessment of contaminated sites. The information is presented in two sets of values:

• The ‘threshold’ trigger value indicating the concentration above which it isnecessary to undertake additional investigation and/or take some form ofremedial action

• The ‘action’ trigger value indicating the concentration above which it isprobable that remedial action will be required

Fig 25. Stockley Park – an example of construction on a brownfield site

When assessing a site, the engineer should remember that the future layout of the sitemay allow local measures to deal with contamination problems instead of remedialtreatment over the whole site. This would be noted in the risk assessment.

10.5 Remedial techniquesThe techniques available fall into two main groups: civil engineering and process-based methods.

Civil engineering methods include:

• Excavation of contaminated material, removal to an approved tip andreplacement with clean material

• Enclosure of contaminant by provision of a designed cover layer, sometimestogether with a barrier wall below ground

Process-based methods include:

• Physical, chemical and biological processes to remove, destroy or convertcontaminants to harmless substances in situor after removal from site

• Thermal treatment to remove or destroy organic contaminants (usually off site)

• Stabilisation to convert and bind contaminants into a less-mobile chemical formboth on site and off

The remedial process should be selected for its applicability, effectiveness andfeasibility. Landfill costs are high and are directly related to the availability of licensedsites and the transportation costs. As processing techniques are developed, costs arefalling and becoming more attractive commercially and environmentally.

The potential impact on the environment of each remedy and any necessary associatedcontrol measures should be evaluated to assess how the factors may constrain thechoice or add to the cost.

10.6 Gas generation and emissionIn certain situations, biodegradation, chemical reactions and leakage from storagetanks may release noxious gases. These may exist in gaseous phase or be dissolved ingroundwater. In addition, they can migrate through the ground under pressure and bydiffusion. The designer should therefore note the following points in preparing designswhere gas is present:

• The natural migration path for gases is from ground to atmosphere

• A structure can create a barrier to gas flow and so lead to a build-up

• Negative pressures relative to atmosphere within the building may encouragegas migration towards the building from stack and/or venturi effects

• A gas membrane should be provided below ground-bearing floor slabs/rafts

• An adequate ventilated void should be provided below a suspended ground floorin addition to a membrane. Alternatively, a vented trench filled with stonearound the perimeter of the building may be provided

• Particular attention should be paid to the building’s service entry points

• A monitoring and warning system should be installed

10.7 Landfill TaxThe Landfill Tax (Contaminated Land) Order1996(40) was introduced in the UK on1 October 1996. Its aim is to provide an incentive to landowners and developers ofbrownfield sites by deterring disposal to landfill and so moving the waste managementoptions towards the developer. By doing this, the Government seeks to encouragewaste minimisation, reuse, recycling and energy recovery from waste.


The Tax is collected on waste material going to landfill by the operator of a sitelicensed under the Environmental Protection Act 1990(9). It is applied at theweighbridge, with a rate of £2/tonne for inactive or inert wastes and £10/tonne for allother taxable wastes. These figures are relevant in April 1999 but are likely to beincreased in the future.

Exemptions from the Tax include:

• Brought-in site engineering materials such as soil or clay

• Dredgings from maintenance of waterways and harbours

• Animal carcasses buried in pet cemeteries

• Waste resulting from clearance of historically contaminated land

Reference to the Order should be made for a list of provisions applying to theexemptions.


(a) Land reclaimation in progress from original refuse site

(b) New building in reclaimed landscape

Fig 26. Waterside HQ for British Airways at Heathrow

10.8 Public register of land that may be contaminatedThe Environmental Protection Act 1990(9) Section 143 places a duty on localauthorities to compile and maintain a register of contaminated land. Subsequentextensive lobbying by landowners against these powers on the grounds of blight andpublic alarm resulted in the powers being withdrawn.

However, the Environment Act 1995(41) gives powers to local authorities to inspectland within their areas for contamination. The owners of sites with a significantpollution problem can be served with a remediation notice.

10.9 Improvement grantsThere are government funds for development sites although not all money is availablefor contaminated sites. For example, Derelict Land Grants (DLG) are available to bothlocal authorities and private developers through English Partnerships.

Urban Development Grants from government funds can provide an incentive toprivate development, particularly in inner city areas. Eligibility for the grant usuallyrequires a substantial private sector investment.



Chapter 11

Construction as a production process


11.1 The processDegradation of the environment from landfill and pollution, depletion of resources andnon-renewable energy is a serious global problem if economic growth is to besustained.

In the long term, this change can be slowed down only by using fewer non-renewableresources, polluting less and sending less waste to landfill. In the short term, economicgrowth can be sustained only by making ‘less’ go ‘further’ in the least harmful way tothe environment.

In the UK, over 70 million tonnes of waste a year is generated from construction andsubsequent demolition. CIRIA has produced a number of guidelines Wasteminimisation in construction; SP135 – Boardroom handbook(42); SP134 – Designmanual(43); SP133 – Site guide(44).

Building is an assembly industry that buys in prefabricated components such asconcrete and bricks, beams, planks and windows, bathrooms and equipment, carpets,installations and fittings. The industry then assembles them on site to someone else’sdesign. It does this by managing the process. Waste management should be seen asjust one part of total management (Fig 27).

11.2 Minimising waste on siteIt is important to keep waste, both during the assembly process on site and by changeof the process, to a minimum. Solutions include:

• Reduction by designing out waste, through prefabrication, and using modularcomponents

• Reuse of shuttering, packaging, etc.

• Recycling of materials such as crushed concrete, reinforcement, excavated soil,scrap metal, plastics and timber (Fig 28)

• Encouraging designers to take expert advice from specialist suppliers duringdesign development

• Getting the component right first time

• Allowing standardisation of as much of the building assembly as possible

• Aiming for off-site prefabrication of components or complete assemblies such asrooms so that offcuts can be minimised and directly recycled

• Minimising the requirement for protective packaging by just-in-time deliveryand properly planned materials handling

• Aiming for reuse or recycling of protective packaging

• Segregating waste by type to enable recycling

11.3 Nature of site wasteA typical construction project wastes little actual building material. The volume ofrubbish varies through the various stages of construction as shown in Fig 29. Mostwaste arises from packaging and from work related to internal finishes. For example, anoffice fitting-out project of 24,000m2 can generate waste which peaks at sixty 2m3 binsper day. Such a quantity needs a dozen or so operatives working full time removingskips, loading compactor lorries and cleaning up. All the waste may need to be takendirect to a landfill site, as it cannot be sorted on site because of its diversecontent.

11 Construction as a productionprocess


• C

ondu

cted

site

vis

its•

Reg

ular

mee

tings

• A

void

cha

nges

• P

lann

ing

ahea

d•

AC

E’s

to s

ite p

erso

n

• In

duct

ion

sem

inar

s•

Not

ices

dis

play

boa

rds

• E

xhib

ition

s•

Mod

els

and

draw

ings

• V

isio

n pa

nels

• C

ondu

cted

vis

its•

Mai

l sho

ts•

New

slet

ters

• P

rogr

ess

phot

ogra

phs

• C

hang

es a

nnou

nced

• P

rogr

amm

es u

pdat

ed•

Pre

ss/M

edia

cam

paig

n

Pre

-eng

inee

ring

envi

ronm

enta

lim

pact

ana

lysi

s

Reg

ular

aud

it by

trad

eco

ntra

ctor

s an

d re

port

Liai

son

with

con

trac

tor

Logi

stic

s m

anag

er

Rig

id e

nfor

cem

ent o

fco

mpl

ianc

e w

ith a

ll st

atut

ory

and

Loca

l Aut

horir

ty r

egul

atio

nsIM

PLE

ME

NTA

TIO

N

• In

duct

ion

wor

ksho

ps a

nd s

emin

ars

• R

epor

ting

• R

egul

ar m

eetin

gs•

Acc

ess

to s

ite p

erso

n

No

upse

ts fo

rC

lient

SA

TIS

FY

CLI

EN

T

Ach

ieve

men

t of

anno

unce

dta

rget

s on

tim

e

Ach

ieve

men

t of

anno

unce

dta

rget

s on

tim

e

INV

OLV

EM

EN

TM

/con

trac

tor/

Pub

lic/T

rade

Con

trac

tors

/Inte

rest

gro

ups

Info

rmat

ion

exch

ange

HO

TLI

NE

Cle

ar a

cces

s to

per

son

resp

onsi

ble

Liai

son

man

ager

• G

ood

safe

ty s

tand

ards

• G

ood

heal

th a

nd w

elfa

re s

tand

ards

• C

lean

lines

s/H

ouse

keep

ing

• Q

ualit

y at

trac

tive

hoar

dind

s/w

alkw

ays/

scre

ens

• Q

ualit

y pr

otec

tion

and

light

ing

• E

ficie

nt r

ubbi

sh r

emov

al•

Ofs

tree

t loa

ding

/unl

oadi

ng•

Qua

lity

acco

mad

atio

n/ca

ntee

ns/to

ilets

on

site

• S

ched

uled

del

iver

ies

• A

dher

ence

to w

orki

ng h

ours

• P

rote

ctio

n of

str

eets

cape

/land

scap

e•

Qua

lity

upda

ted

mul

ti-lin

gual

sig

nage

• G

ood

com

mun

icat

ion

amon

gst c

ontr

acto

rs•

App

licat

ion

of b

est p

ract

ice

to c

ontr

ol n

oise

, dus

t etc

• C

onsi

dera

te B

uild

ers

Sch

eme

• N

eigh

bour

s in

form

atio

n pa

ck

Liai

son

with

Pol

ice

and

auth

oriti

es

Fig

27

. G

oo

d m

an

ag

em

en

t o

f co

nst

ruct

ion

Packaging may be timber, cardboard, paper, polythene, other plastics, polythene ormetals. Other waste may include plasterboard, timber or metal studwork, electriccable, metal ductwork and pipework, bricks, blocks, mortar, raised flooring, carpet andtiles (Figs 30 & 31). Unused adhesives, solvents, mastics, paint and so forth may alsobe discarded.

Space does not often permit all these categories of waste to be kept separate within theconfines of a building site. In any case, site operatives may find it hard to decidewhich waste material belongs to which category. Sorting site waste into categoriestherefore needs to be done off site after transporting to sorting stations uncompacted.This means that increased numbers of vehicle journeys are required from site, beyondthose required for compacted waste. Increased sophistication in waste disposal will beintroduced only if the current costs of disposal become prohibitive or if there is acontinued tightening of legislation.


2500

2000

1500

1000

500

0

Tota

l cub

ic y

arda

ge o

f rub

bish

Str

uctu

re Con

stru

ctio

n

Ser

vice

s

Fin

ishe

s

Dec Feb Apr June Aug Oct DecJanNovSepJulMayMarchJan

Month of disposal

Fig 29. Typical volumes of compacted rubbish from site

Fig 28. A railway bridge across The Rhine dismantled ready for recycling


Fig 32. Transportation of construction waste

DryliningPlasterboard

Studs

M&E ServicesCable

DuctworkPipework

BlocksBricksMortar

Raised flooringCarpet

Ceiling tilesCeramic tiles

Containers,tins, tubesAdhesivesSolventsMasticPaint

SKIP

Pallets

Boxes

Shrink wrap

Bubble wrap

Polystyrene blocks

Polystyrene chips

Timber

Cardboard

Paper

Plastics (various)

Metals

PACKAGING

Fig 30. Rubbish skip a on construction site

Fig 31. The wide variety of site waste


• P

lant

; Equ

ipm

ent;

Veh

icle

s•

Per

sona

l rad

ios

• P

A a

nd c

omm

unic

atio

n sy

stem

s•

Pili

ng•

Dril

ling;

Cut

ting;

Saw

ing

• D

elay

s•

Tra

ffic

jam

s•

Par

king

ove

rload

s•

Obs

truc

tion

• N

oxio

us s

ubst

ance

s (e

.g a

sbes

tos)

• M

ud; P

uddl

es; W

ater

• A

irbor

ne d

ust

• R

ubbi

sh•

Flo

odlig

hts

• S

mel

ls•

Sm

okin

g

• S

tree

t lig

htin

g qu

ality

• V

ehic

le r

outin

g an

d ac

cess

alte

red

• P

edes

tria

n ro

utin

g an

d ac

cess

alte

red

• U

tiliti

es d

ownt

ime

• P

ublic

ser

vice

s di

scon

tinue

d•

Crim

e in

crea

sed

• P

arki

ng d

isco

ntin

ued

• L

oadi

ngs;

Unl

oadi

ng; B

lock

ages

• S

tree

t blo

cked

or

clos

ed•

Hoa

rdin

gs e

rect

ed•

Roa

d w

idth

s re

stric

ted

• O

ut o

f hou

rs w

orki

ng•

Air

right

s af

fect

ed•

Par

ty w

all r

ight

s af

fect

ed•

Fire

ris

k in

crea

sed

• P

ress

ure

on lo

cal s

ervi

ces

• In

crea

sed

popu

latio

n

• P

oten

tial i

mpa

ct o

n op

erat

ion

of

¥ b

usin

ess

• T

he p

ublic

• T

he c

lient

• T

he te

nant

• T

rade

con

trac

tors

• R

esid

ents

• L

ocal

com

mun

ity a

ssoc

iatio

ns•

Loc

al a

utho

rity

• S

tatu

tory

aut

horit

ies

• P

olic

e•

Fire

• A

mbu

lanc

e•

Util

ities

• N

eigh

bour

s•

Com

mer

cial

/Offi

ce O

wne

rs•

Eng

lish

Her

itage

• A

rcha

elog

ists

• P

ublic

tran

spor

t•

San

itatio

n co

ntra

ctor

s

Noi

se

Traf

fic

Pol

lutio

n

Dis

rupt

ion

Vib

ratio

n

Con

stru

ctio

n/T

empo

rary

Wor

ks

• L

oss

of tr

ade

• D

istu

rban

ce a

nd d

isco

ntin

uity

• A

ctua

l nui

sanc

e an

d he

alth

effe

cts

• F

rust

ratio

n an

d de

lay

Logi

stic

sm

anag

er

Liai

son

man

ager

Pre

-eng

inee

ring

envi

ronm

enta

lim

pact

ana

lysi

s

TH

EB

UC

KS

TO

PS

HE

RE

Fig

33

. E

nvi

ron

me

nta

l im

pa

ct o

f co

nst

ruct

ion

11.4 Reducing environmental impactThe inevitable conflict between a client’s right to develop a site and theneighbourhood’s right to remain undisturbed must be reconciled. Forward-lookingmanagement and planning techniques are required, helped by off-site assembly andjust-in-time delivery techniques.

The typical approach to the management of disturbance from noise, traffic andpollution illustrated in Fig 33 has much to recommend it. Each project needs arigorous logistics analysis if environmental impact on neighbours is to be minimised.



References, bibliography andacknowledgements


1. World Commission on Environment and Development. Our Common Future(The BruntlandReport) Oxford University Press, Oxford and New York, 1987

2. Engineering Council. Guidelines on Environmental issues.London, The Engineering Council,1994

3. United Nations. Agenda 21: Programme for action for sustainable development. Conference onenvironment and development, Rio de Janeiro, 1992. United Nations, 1993.

4. The Basel Convention on Control of transboundary movement of hazardous wastes and theirdisposal.1989

5. Treaty on the European Union,Maastricht 7/2/92

6. This common inheritance: Britain’s Environmental strategy.London, HMSO, 1990. Cm 1200

7. Sustainable development: the UK strategy.London, HMSO, 1994. Cm 2426

8. Department of the Environment. Making waste work: a strategy for sustainable wastemanagement in England and Wales; summary.London: DoE, 1995

9. Environmental Protection Act 1990

10. Clean Air Act 1993

11. Water Resources Act 1991

12. Water Industry Act 1991.

13. Town and Country Planning Act 1990

14. Department of the Environment. Planning Policy Guidance: Green belts.PPG2, London, DoE,1995

15. Department of the Environment. Planning Policy Guidance: Town centres and retaildevelopment.PPG6. London, DoE, 1996

16. Department of the Environment, Transport and the Regions. Planning Policy Guidance ontransportation. Implementation 1994–1996.PPG13. London, DETR, 1997

17. Department of the Environment, Transport and the Regions. Town and country planning(development plans and consultation) (departures) directions.London: DETR, 1999. PlanningPolicy Guidance Note PPG12

18. Home Energy Conservation Act 1995

19. Special Waste Regulations 1996

20. User Responsibility (Packaging Waste) Regulations 1997

21. Sustainable Construction.1st Annual Conference. Tampa, Florida, 1994

22. Environmental Code of Practice for Buildings and their Services.BSRIA

23. BS EN ISO 14000: 1996 Environmental management systems. Specification with guidance foruse.London, BSI.

24. Hart, S. L.: ‘Beyond Greening– Strategies for a sustainable World’. Harvard Business Review,January/February 1997, 75 (1), pp 66-76

25. Gordon, A.: ‘Architecture: for love or money?’ RIBA Journal,December 1971, pp 535-540

26. Institution of Structural Engineers. Appraisal of existing structures(2nd ed.) London, SETO, 1996

References


27. Construction (Design and Management) Regulations 1994

28. Howard, N., Edwards, S., and Anderson, J.: BRE methodology for environmental profiles ofconstruction materials, components and buildings,BRE, Construction ResearchCommunications, BR 370, 1999, ISBN 1 86081 294 5

29. Howard, N., Shiers, D., and Sinclair, M.: The Green Guide to Specification,BRE Report 351,1998, ISBN 1 860812 42 2

30. Eaton, K. J., and Gorgolewski, M. T.: ‘Environmental impact of steel piling’. Paper presentedat the International Conference on Steel in Green Building Construction, Orlando, Florida, 18-21 March 1998

31. Eaton, K. J., and Amato, A.: ‘Using life cycle assessment as a tool for quantifying greenbuildings’. Paper presented at the International Conference on Steel in Green BuildingConstruction, Orlando, Florida, 18-21 March 1998

32. Eaton, K. J., and Amato, A.: ‘A comparative life cycle assessment of steel and concrete framedoffice buildings’. Paper presented at the Second International Conference ‘Buildings and theEnvironment’ organised by CIB Task Group 8 and CSTB, Paris, France on 9-12 June 1997

33. Eaton, K. J.: ‘Think sustainable construction’. New Steel Construction,5, No. 4,August/September 1997, p 33

34. Eaton, K. J., and Amato, A.: A comparative environmental life cycle assessment of modernoffice buildings.SCI-P-182, The Steel Construction Institute, Ascot, 1998, ISBN 1 85942 058 3

35. Institution of Structural Engineers. Aspects of cladding.London, SETO, 1995

36. CIBSE. Natural ventilation in non-domestic buildings. London, CIBSE, 1997

37. Vale, B., and Vale, R.: Green architecture: design for a sustainable future.London, Thames &Hudson, 1991

38. NATO Committee for Challenges to Modern Society. Pilot Study on Research, Developmentand Remediation Technologies for Contaminated Land.1992

39. UK Interdepartmental Committee on the Redevelopment of Contaminated Land (ICRCL).Guidance Notes 17/78, 18/79, 23/79, 42/80, 59/83, 61/84, 64/85

40. Landfill Tax (Contaminated Land) Order 1996

41. Environment Act 1995

42. Coventry, S., Woolveridge, C., and Patel, V.: Waste minimisation and recycling inconstruction: Boardroom handbook.CIRIA SP 135. London, CIRIA, 1999

43. Coventry, S., and Gutherie, P. M.: Waste minimisation and recycling in construction: Designmanual.CIRIA SP 134. London, CIRIA, 1998

44. Gutherie, P. M. et al.: Waste minimisation in construction: Site guide.CIRIA SP 133. London,CIRIA , 1997

Statutory Documents*Control of Pollution (Special Waste) Regulations 1980

Control of Substances Hazardous to Health Regulations 1988 (COSHH)

Landfill sites: Development Control DOE Circular 17/89, Welsh Office 38/39

Building Regulations 1991 (Section C)

Chemicals (Hazard Information and Packaging (or Supply) Regulations 1994 HMSO

+Special Wastes Regulations (1996)

*now revoked and replaced by +

Guidance DocumentsAssociation of Geotechnical and Geoenvironmental Specialists. Geoenvironmental Site Assessment –Guide to the Model Document Report.The Assn, 1996.

BRE BREEAM/Version 2/91 An environmental assessment for new superstores and supermarkets.Watford, BRE, 1991, BR207

BRE BREEAM/New homes. Version 3/91. An environmental assessment for new homes.Watford,BRE, 1991, BR208

BRE BREEAM/New offices. Version 1/93. An environmental assessment for new office designs.Watford, BRE, 1993, BR234

BRE BREEAM/ Existing Offices. Version 4/93. An environmental assessment for existing officebuildings.Watford, BRE, 1993, BR240

BRE BREEAM/New Industrial Units. Version 5/93. An environmental assessment for new industrial,warehousing and non-food retail units.Watford, BRE, 1993, BR252

British Drilling Association. Guidance Notes for the Safe Drilling of Landfills and Contaminated Land.Upper Boddington, Nr Daventry, British Drilling Association (Operations Ltd.),1992

British Steel. Guide to thermal capacity in buildings.Scunthorpe, British Steel Sections, Plates andCommercial Steels. 1999

British Steel. Life cycle assessment in steel construction.Scunthorpe, British Steel Sections, Plates andCommercial Steels. 1999

British Steel. Recycling and re-use in steel. Scunthorpe, British Steel Sections, Plates and CommercialSteels. 1999

Card, G. B.: Protecting development from methane. London, CIRIA, 1995. Report 149

CIBSE Applications Manual AMIO:1997 Natural Ventilation in Non-Domestic Buildings

CIRIA Environmental issues in construction: a review of issues and initiatives relevant to the building,construction and related industries.London, CIRIA. SP93-94, 1993

CIRIA Remedial Treatment for Contaminated Land,vols. 1–12. London, CIRIA. 1995–1998. CIRIASpecial Publications SP101 - SP112, 1995

CIRIA Environmental issues in construction – a strategic review. London, CIRIA. CIRIA C510, 1999

Coventry, S., and Woolveridge, C.: Environmental good practice on site.London, CIRIA. CIRIA C502, 1999.


Bibliography

Davies, V. J., and Tomasin, K.: Construction Safety Handbook, 2nd edn. London, Thomas Telford, 1996

Department of the Environment, Transport and the Regions. ‘Sustainability counts: consultation paperon a set of “headline” indicators of sustainable development’. London, DETR, 1998

Department of the Environment, Transport and the Regions. ‘Making biodiversity happen: asupplementary consultation paper to “Opportunities for change”.’ London, DETR, 1998

Department of the Environment, Transport and the Regions. ‘Opportunities for change: consultationpaper on a UK strategy for sustainable construction’. London, DETR, 1998

Department of the Environment, Transport and the Regions. A summary of the responses of less wastemore value.London, DETR,1999

Department of the Environment, Transport and the Regions. Town and country planning (developmentplans and consultation) (departures) directions.London: DETR. Planning Policy Guidance NotePPG12, p17, 1999

DoE Contaminated Land Research Report SeriesCLR 1-6. London, DoE, 1994-95

Gorgolewski, M.: The role of steel in environmentally responsible buildings.Ascot, SCI. SCI Pubn 174,1999

Harries, C. R., Witherington, P. J., and McEntee, J. M.: Interpreting measurements of gas in theground. London, CIRIA, 1995. CIRIA Report 151

Howard Humphreys & Partners. Managing Demolition and Construction Wastes. Research contractPEZD 7/1/434 HMSO London, 1994

Howard, N., Edwards, S., Anderson, J.: Methodology for environmental profiles of constructionmaterials, components and buildings. Watford, BRE. BR370. 1999

Institution of Civil Engineers. Design and Practice Guide on Contaminated Land.London, ThomasTelford/Institution of Civil Engineers, 1994

Institution of Chemical Engineers. Future life. Engineering solutions for the next generation.Rugby,IChemE, 1997

Institution of Civil Engineers. Managing and Minimising Construction Waste: a practical guide.London, Thomas Telford/Institution of Civil Engineers, 1995

Institution of Civil Engineers. Environment file.London, ICE, 1996

Kreigger, P. C.: ‘Ecological Preparation of Building Materials’, Materials & Structures,20, pp 248-254. 1987

Leach, B. A., and Goodger, H. K.: Building on Derelict Land.Croydon; London, PSA; CIRIA. PSACivil Engineering Technical Guide 60; CIRIA SP78. 1991

National Building Specification Services. The Greening report. Available at websitewww.nbsservices.org.uk/nb/green/htm

O’Riordan, N. J., and Milloy, C. J.: Risk assessment for methane and other gases from the ground.London, CIRIA. CIRIA Report 152. 1995

Raybould, J. G., Rowan, S. P., and Barry, D. L.: Methane investigation strategies.London, CIRIA.CIRIA Report 150. 1995

SETAC. Guidelines for Life-Cycle Assessment: A ‘Code of Practice’.Washington, SETAC. 1993

Shorrock, L. D., and Henderson, G.: Energy use in buildings and carbon dioxide emissions.Garston,BRE Report 170. 1991

West, J. M., Atkinson, C. J., and Howard, N. P.: ‘Embodied energy and carbon dioxide emissions forbuildings’. In CIB Conference on Buildings and the Environment. BRE, May 16-29, 1994

2nd International Conference on Buildings and the Environment,12 June 1997 Paris. Vols 1 & 2.Centre Scientifique et Technique do Batiment, 1997



Acknowledgements

Cover illustrations

The West Stow Country Park Museum and cafeteria (courtesy of the Timber Research andDevelopment Association)

The Commerzbank, Frankfurt (courtesy of Ove Arup & Partners)

The new BRE Building 16 (courtesy of Buro Happold).

Main text

Fig 4. Courtesy of Keith Eaton.


Fig 8. Courtesy of Buro Happold; Civil/structural engineers:Buro Happold; Developer:MEPC; Client:IBM; Architect: Michael Hopkins & Partners; Services:FHP; Construction: Costain Construction

Fig 10(a). Courtesy of British Steel SPCS.

Fig 10(b). Courtesy of Christine Ottewill/Whitby Bird & Partners/

Fig 14. Courtesy of BHP.




Fig 18. Courtesy of British Steel SPCS.

Fig 19. Courtesy of Buro Happold; Structural and services engineers:Buro Happold; Client: OpenUniversity; Architect: Fielden Clegg Design; Construction management: MACE Ltd.

Fig 20. Courtesy of Buro Happold; Civil/structural engineers:Konig und Hoenisch with Buro Happold;Client: RWE AG; Architect: Ingenhoeven Overchek & Partners; Services:HLT with Buro Happold;Constructor: Hochtief

Fig 21(a). Courtesy of Buro Happold

Fig 21(b). Courtesy of Buro Happold/Mandy Reynolds


Fig 26(a). Courtesy of Buro Happold

Fig 26(b). Courtesy of Buro Happold/Mandy Reynolds


Appendices


This appendix was written by Professor Bill Biggs in 1995, and at that time the factsand figures that were available to him are reflected in the text. However, much workhas been carried out in recent years on the environmental aspects of selectingconstruction materials, and recent publications such as the BRE Green Guide(A1.1) givethe latest design guidance. For convenience, a table of embodied energy andembodied CO2 data from reference A1.2 is included at the end of this Appendix.

IntroductionBy now designers have a reasonable understanding of the factors affecting cost in useand, in the present context, of the operational use of energy in buildings. But thebroader environmental consequences of producing buildings have been poorly defineduntil the last decade or so when these have tended to parallel – and even sometimes tooutweigh – the purely economic issues surrounding construction.

In this Appendix we explore some of these issues, although it must be admitted thatmany are, as yet, still unquantifiable and, even where attempts at quantification havebeen made, the data is gleaned from several sources and by several different methods.Thus numerical data must be regarded, at best, as generally unreliable.

And so this Appendix is for guidance only and to provoke a way of thinking – much ofit will be already familiar to practising engineers but it represents a first attempt to bringtogether some of the many different approaches which have appeared in recent years.Note, however, that we do not discuss energy in use – this has been the subject of manyseparate investigations and the controlling factors are now quite well understood.

Environmental auditing(A1.3)

An environmental audit includes both energy-related and non-energy-related factors,each of which has direct and indirect components.

Direct environmental effects include:

• Emission of gas, particulates, etc.

• Air, water and solid waste from processing and handling

• Depletion of non-renewable reserves, etc.

Indirect environmental effects include:

• Damage to terrestrial and aquatic habitats

• Production of hazardous wastes, etc.

The direct environmental effects are typically more readily quantifiable, although littleis available in a form that is useful to designers. Every material or component used inbuilding involves both direct and indirect components of energy. We call this the‘embodied’ energy, the indirect energy, i.e. that which is consumed in the productionof materials, processing, transportation etc. represents the larger percentage –estimates put it around 90-95% of the total. Howard(A1.4) expressed this moregraphically, estimating that, in 2–5 years, occupation of a detached house will exceedthe energy embodied in its fabric.

Life cycleBut of course the embodied energy of a component in situ is only a part of theequation. We should add to this the energy cost of maintaining, repairing andreplacement over the lifetime. The following hypothetical argument may help tovisualise the situation.

Appendix A Some criteria for theselection of materials


Consider a building as a durable asset containing C tonnes of material which willdeteriorate over its service life t. The annual material usage is therefore y1 = C/t andthe total usage from, say t1 to t2, is:

lQ ctctt

dtdt C t ClCl ttn n

t

t

t

t2

11

2

1

2= = =# 6 @

Thus, to upgrade in order to yield a longer life – e.g. in this instance to double the lifefrom t1:

.Q ClCl C2 0 6969n= =

i.e. upgrading saves 0.31C and this will be true so long as Q < C.

But Q = C when t2/t1 ≥ 2.178. This trebling the life expectancy would be uneconomic.

Consider now maintenance, repair and replacement. These are of an intermittentprocesses but rather than use a step function we use a continuous linear function

y2= bt where b is a ‘maintenance coefficient’.

The total maintenance consumption of materials is

btbt dtdt btbt12o

t 2=# (1)

and, at any time:

y y y

Ct

btbt

1 2= +

= +

and the optimal life occurs when the rate of material usage is zero, i.e. when:

. .

C

i e

dydy dtdtt

b

t C b

02= + =

=

whence, by substitution in equation (l) above when:

y CbCb2=

Different materials deteriorate at different rates so that there is a whole family ofcurves yr = brt each giving a different optimal life and materials usage (Fig A1.1).

y1

t1 t2optimaleconomiclife for b

b

a

t

Fig A1.1 Optimal life compared with material usage

Thus, for a low coefficient (i.e. a durable material such as concrete), the net curve (e.g.(a) will tend to flatten out and the life expectancy is not critical. With a highmaintenance coefficient, the curve will bend sharply and the optimum life is reachedmore quickly. When the optimum life is achieved three possibilities arise:

• The total level of materials consumption increases due to a progressive increasein the maintenance load.

• The level of consumption stays constant, i.e. the net curve flattens out as theoptimum technical life and economic life coincide. In this case it may beworthwhile to commit more material resources to maintenance since the annualmaterial usage of the building decreases.

• The amount needed for maintenance decreases – material consumption isreduced in the short term but, in the long term, obsolescence will be accelerated.

The above argument, though hypothetical, applies to whatever units we choose for Cwhether fiscal cost, embodied energy cost, etc. It demonstrates a familiar situation,namely that buildings become uneconomic long before they reach the end of theirtechnical life so that renovation is often a more sensible course than rebuilding whenthe whole cycle starts again.

We next examine some of the approaches to the problems of energy content ofbuildings.

Weight/strength analysisClearly the less material we need to perform a given function the less the embodiedenergy of the structure or assembly. Minimisation of weight is a controlling parameterin, for example, aeronautical engineering since a lower structural weight is reflected inan increased payload.

However, even where minimum weight is not a prerequisite, there are often goodreasons for making a minimum weight analysis. Thus Cox(A1.5) states that ‘Even whenother standards apply, weight is at least a dominant factor – the prime costs ofmaterials and the costs of erection both follow weight and, in many instances, areduction in weight reduces operating costs. At the very least the designer is assuredthat he is in a position to assess whether or not the excess weight of a practicalstructure is justified in, say, a saving in production and assembly cost.’ Here again theargument is as true about energy cost as it is about fiscal costs.

Generally speaking, the most important criteria are strength σ and modulus E so that ithas become customary to compare materials on the basis of their specific propertiesσ/ρ and E/ρ where ρ is the density. Shanley(A1.6) has pointed out the inconsistency ofthis. The object of a minimum weight analysis is to find the least weight (and hencethe least embodied energy) which is required to determine the strength or stiffness of agiven structure so that it is more logical to think in terms of weight/unit strength orstiffness rather than strength/unit weight.

In the case of simple tension we may assume that the actual shape of the cross-sectionhas only secondary effects so that the allowable stress is:

σA = P/A

where P is the applied load. Since the weight is:

W = ρV = ρAL

where L is the distance over which the load must be carried, the weight/strength ratiois:

ororW P P LL

wA

LA

2= =t

tv

v


where the ‘geometric’ term contains only the length L and the material is controlled byσΑ/ρ. Similarly, where deflection is the controlling factor P/L = E/ρ.

It is, however, not always quite so obvious. Consider a simple cantilever of squaresection and of length L.

The elastic deflection is:

EtEt

l P44

3

=d (2)

where t is the thickness.

The weight is given by:

W = It2ρ

so that:

tLW

1 2

=tc m

Substituting for t in equation 2 we have:

. .i e

El PlPl

W

M L PE

4

4

3 2

2

21 2

51 2 2

1 2

=

=

dt

d

t

d f

d d

n p

n n

so that the weight of the beam for a given stiffness of P/δ is minimised for a materialwith a minimum value (ρ/E)1/2 or, by using the earlier notation, by maximising E/ρ2).Similar analyses by Gerard(A1.7) have been summarised by Kennedy(A1.8). Much thesame argument applies to cost. Thus the price per tonne p whence

PrPriceice pE

L P41 2 2

1 25

=t

ddd nn

Embodied energyAs shown by the references, these concepts are by no means new. But they werederived, principally, on the basis of saving cost and only now can we return to them interms of energy usage. That there is some sort of relationship between cost and energymust apply, since the prime cost of any material must presumably include the cost ofthose elements of winning, processing and supplying the material to site. This doesnot, however, seem to be true.

The concept of embodied energy has been taken up for school buildings in Hampshirethrough Sir Colin Stansfield Smith and is described in a joint report with theUniversity of Plymouth(A1.9). Few materials were considered and the basic data comesfrom a paper by Baird and Chan(A1.10). Among the data reported by them are given inTable A1.1, where, by weight, steel is 7 times more energy-intensive than concretebut, by volume 76 times more intensive.


P

dδ

Similar calculations based upon functional performance have been supplied byBuchanan and Marsh, although the argument between the numerical values suggeststhat the same source may have been used by both authors.

Ecological propertiesIn a series of papers, Kreijger has attempted a more ambitious survey involving, interalia, issues of pollution and deforestation. Before discussing his papers, it is useful toconsider briefly some of these factors.

Carbon dioxide emissionCarbon dioxide is released into the atmosphere whenever fuel is burnt, so that there isa correlation between embodied energy and CO2 emission. For example, any processinvolving large amounts of electricity (e.g. aluminium, polymers, etc.) will generatelarge quantities of carbon dioxide, whereas materials such as timber are low inembodied energy and consequently will generate less CO2.

DeforestationThis has probably caused more controversy than any other issue with particularconcern over the tropical forests. But, to put the problem in context, it should be notedthat only about 6% of the tropical non-coniferous roundwood enters the internationaltrade: the rest is cleared for agricultural purposes, for local construction or for fuel.Nonetheless, the problem is serious and well-managed timber production (e.g. as inNorway, Finland and even Ghana) remains a primary necessity. But, as with CO2emission, the problem is primarily one of management.

In his series of papers, Kreijger has attempted to tackle these and other, more global,problems. He treats materials not in terms of production costs, e.g. £/tonne orenergy/tonne, but rather in terms of the cost of buying one unit of usable property, e.g.£/unit or modulus or strength. He tries to cover the ‘cost’ in terms of many differentfactors – price, energy, water usage, deforestation, pollution, etc.

Ecological properties of materialsThe problem is not new. The whole process of biological evolution depends upon it.Given limited resources of food, habitat, etc., the metabolic cost of improving oneproperty must be balanced against the likelihood of deterioration in another. And so itis in engineering: an increase in strength or hardness at the expense of sacrificingductility is a familiar example.

But here again the problem is familiar. In those structures, such as aeronautics, whereweight is crucial, we are accustomed to the use of specific properties such as strengthor modulus per unit of weight and these often rate materials in a different order ofsuitability than those obtained by a consideration of the properties alone. And the


Material Embodied energy

By weight By volume

MJ/kg MJ/m3

Concrete 2 4 800

Timber 5 3 500

Steel 35 266 000

Aluminium 145 377 000

Table A1.1 Basic data on embodied energy (after Baird & Chan (A1.10))

fiscal cost is some reflection of this – the cost of producing 1kg of aluminium isseveral times that of producing 1kg of steel. We may do well to recall the techno-economic ‘law’ proposed by Alexander and Appoo (1977): ‘The cheaper it is to buytensile strength, the greater is the tonnage of the material used’.

Kreijger has probably taken the problem further than most in three papers(A1.11, A1.12,

A1.13). In the first, he discusses the global economics of producing materials but givesno indication of how he reaches the conclusion of his second paper (1987) in which herates materials in terms of the cost (in whatever units) of one unit of engineeringusage. I have tried to assess and analyse these but, so far, no solutions are apparent. Icannot find any way in which he converts, say, a total world energy consumption intoconsumption for steel production and hence to energy consumption per unit. And, I donot know how or from where up-to-date values may be obtained. In what follows, Itake Kreijger’s figures on trust and present them in Table A1.2. Because of the widearithmetical scope Kreijger plots these on logarithmic scales, e.g. Figs A1.2 and A1.3,which I find confusing.

In an attempt to render these figures dimensionless, I have tried to recalculate them ona scaled basis. Thus, that element which ‘costs’ the most – whether in money, energyetc. – is rated as 100% and all the others are rated as proportions of this.

( )

PrPr

SealingSealingfactorfactor SFSFHighestHighestfactorfactor

ScaledScaledpropertyproperty ActualActual opertyoperty SFSF

100100

#

=

=

By this procedure, each property is given equal importance and, perhaps, an aggregatevalue gives a total picture of the ecological cost. These data are presented in Table A1.3 .


Table A1.2 (Adapted from Kreijger (1987)

Steel Glass Brickwork Sand/LimeReinforceconcrete

Wood

Strength Modulus Strength Modulus Strength Modulus Strength Modulus Strength Modulus Strength Modulus

Cost £ perunit 27.0 0.031 101.1 0.045 29.5 0.045 20.0 0.030 9.7 0.005 26.7 0.034

Energy MJper unit 983 1.12 1867 0.86 1467 2.2 653 0.98 444 0.21 143 0.18

Water l/m3

per unit1788 2.04 — — 160 0.24 133 9.8 47 0.023 — —

PollutionSO2Kg/m3 perunit

0.058 0.67 0.107 0.49 0.24 3.6 0.053 0.80 0.074 0.36 — —

Dust/sootKg/m3 perunit

0.163 1.85 — — 0.12 1.8 0.12 1.8 0.074 0.36 — —

Desoiling/deforest-ation perunit

0.16 1.9 — — 0.19 2.8 0.027 0.40 0.074 0.36 357 0.455

Labourman hourper unit

0.34 3.9 — — 0.50 7.6 0.18 2.7 0.26 1.23 — —


ener

gy(M

J/m3 N/m

m2 σ)

glas

s

5000

4000

3000

100

200300400

500

50

cost (Fl/m3N/mm2σ)

brick

work

(kg/m

3 N/mm

2 -σ)

(kg/m3N/mm2σ)

dust

sand lime brickwork

steel

1000

stee

lre

inf.

conc

rete

500

300

200

400

wood

deforestation

(l/m

3 N/mm

2 σ)

labour

(mh/m 3N/m

m 2-σ)

desoiling

water

40

30

20

10

5

3

1

300020001000

500400300200

100

504030

20

0.5

0.4

0.3

0.2

0.1

0.04

0.03

0.02

0.5 0.

4 0.3

0.2

0.1

0.05 0.

04 0.03

0.02

0.2

0.3 0.4 0.5

1.0

0.1

0.2

0.3

0.40.5

(m3/m3N/mm2-σ)

(σ = tensile orflexural strength)

Steel

GlassBrickworkSand limebrickwork

Reinforcedconcrete

Wood

reinf.concrete

deforestation

ener

gy(M

J/m3 N/m

m2 -E

)

0.1

(ε, modulus of elasticity)

desoiling(m3/m3N/mm2-E)

labour

(mh/m 3Nm

m 2-E)

(kg/m

3 N/mm

2 -E)

dust

SO2(Kg/m3N/mm2-E)steel

brickw

ork

sand

lime

bric

kwor

k

bric

kwor

k woo

d

glass

0.050.040.03

0.020.02

0.03

0.04

0.05

steel0.2

0.30.40.5 (l/

m3 N/m

m2 -E

)

water

0.5

0.4

0.3

0.2

54

32

10-3

5 4 3 2 10-4

5 4 3 2

10-4

54

32

10-5

54

32

10-4

10-3

cost (Fl/m3N/mm2-E)

Steel

GlassBrickworkSand limebrickwork

Reinforcedconcrete

Wood

Fig A1.2 Ecological profile for some materials: properties expressed in units pervolume per N/mm

2

strength (limit state of strength)

Fig A1.3 Ecological profile for some materials: properties expressed in units pervolume per N/mm

2

modulus of elasticity (serviceability state)

At the end of it all, I remain unconvinced that this sort of approach really matters. I amno economist but surely, if steel costs, say, £1000 per tonne, then that fiscal costincludes the cost of digging it up, processing the material, turning it into a usefulproduct, etc. So that, at the end of the day, the only things that really matter are thethings we give away for free – dust, gas, contamination, etc. There is no charge forthese and the figures are, in any event, highly suspect.

ReferencesA1.1 Howard, N., Shiers, D., and Sinclair, M.: The Green Guide to Specification,BRE Report 351, 1998

A1.2 Eaton, K. J., and Amato, A. A.: A comparative environmental life-cycle assessment of modernoffice buildings.Ascot, SCI Pubn 182. 1988

A1.3 Cole, R. J., and Rousseau, D.: ‘Environmental auditing for building construction: energy andair pollution’. Building and Environment, 27 (1) 1992

A1.4 Howard, N.: ‘Energy in balance’, Building Services, May 1991

A1.5 Cox, H. L.: Design of structures of least weight, Pergamon Press, Oxford 1958.

A1.6 Shanley, F. R.: Weight/strength of aircraft structures,McGraw Hill, New York, 1952

A1.7 Gerard, G.: ‘Comparative efficiencies of aerospace pressure vessel design concepts’, AIAAJournal, 4, (12), 1966

A1.8 Kennedy, A. J.: ‘The potential of composite materials’, Composite Materials,Iliffe, London, 1966

A1.9 McCartney, K.: The culture of timber, School of Architecture, University of Plymouth, 1994

A1.10 Baird, G., and Chan Seong Ann: Energy costs of houses and light construction buildings, ReportNo 76, New Zealand Energy Research and Development Committee, Auckland, NZ, 1983

A1.11 Kreijger, P. C.: Materials and construction,6 36, 1973

A1.13 Kreijger, P. C.: Materials and construction,20, 1987

A1.14 IABSE, British National Group colloquium, Kreijger, P C, September 1981


Table A1.3 Scaled ecological properties

Steel Glass Brickwork Sand/lime Reinforcedconcrete Wood

Strength Modulus Strength Modulus Strength Modulus Strength Modulus Strength Modulus Strength Modulus

Cost £ perunit 26.7 68.9 100 100 29.2 100 19.8 66.7 9.6 10.9 26.4 75.6

EnergyMJ perunit

52.7 50.9 100 39.1 78.6 100 35.0 44.5 23.8 9.5 7.7 8.2

Waterl/m3 perunit

100 100 — — 8.9 11.8 7.4 9.8 2.6 1.1 — —

PollutionSO2KF/m3 perunit

24.2 18.6 44.6 13.6 100 100 22.1 22.2 30.8 10.0 — —

Dust/sootKg/m3 perunit

100 100 — — 73.6 97.3 73.6 97.3 45.4 19.5 — —

Desoiling/deforest-ation perunit

0.45 67.9 — — 0.05 100 0.008 14.2 0.021 12.8 100 16.3

Labourman hourper unit

68.0 51.3 — — 100 100 36.0 35.5 52.0 16.2 — —


Table A1.4 Values of energy and CO2 emissions

Material/componentTransport componentof embodied energy(GJ/t)

Total embodiedenergy, includingtransport (GJ/t)

TotalembodiedCO2 (kg/t)

Deliveredenergy

Primaryenergy

Deliveredenergy

Primaryenergy

1. Excavation & disposal 0.086 0.095 0.086 0.096 7

2. In situconcrete substructure 0.06 0.067 0.064 0.84 119

3. In situconcrete superstructure0.06 0.067 0.85 1.09 163

4. Common Bricks 0.045 0.05 2.7 5.8 490

5. Facing bricks 0.045 0.05 5.6 11.7 878

6. Mortar 0.06 0.067 0.64 0.84 122

7. Hardcore and aggregate 0.09 0.1 0.16 0.28 15.8

8. DPM/DPC 0.6 0.67 75 120 8280

9. Reinforcement 0.4 0.44 25 26.8 2030

10. Concrete blocks 0.13 0.14 1.04 1.31 203

11. Precast concrete 0.2 0.22 1.07 1.36 208

12. Timber 3.4 3.8 6.4 13 1644

13 Chipboard 3.4 3.8 16 36 2560

14. Plywood 3.9 4.3 8.2 17 1465

15. Mandolite 0.06 0.067 14 63 1400

16. Vicuclad 0.13 0.14 20 70 2000

17. Structural steel 0.4 0.44 25 26.8 2030

18. Sheet steel 0.31 0.34 29 34 2698

19. Stainless steel 0.4 0.44 12 33 1656

20. Roofing felt 0.13 0.14 38 75 3800

21. Roof insulation 0.4 0.44 22 35 2606

22. Wall insulation 0.4 0.44 22 35 2606

23. General insulation 0.4 0.44 22 35 2606

24. Asphalt 0.4 0.44 3.3 5 330

25. Stone chipping 0.05 0.056 0.27 0.3 22

26. Natural slate 0.1 0.11 0.14 0.16 12


Table A1.4(continued)

Material/components Transport component ofembodied energy (GJ/t)

Total embodied energy,including transport (GJ/t)


Deliveredenergy

Primaryenergy

Deliveredenergy

Primaryenergy

27. Crushed slate 0.1 0.11 0.18 0.2 15

28. Concrete tiles 0.06 0.067 1.04 1.3 203

29. Paving 0.06 0.067 1.04 1.3 203

30. Lead 0.19 0.21 100 134 9500

31. Resin 0.6 0.67 124 200 21400

32. Plaster 0.06 0.07 1.03 1.4 93

33. Plaster-board 0.13 0.14 2 2.7 180

34. Paint 0.6 0.67 50 70 5350

35. PVC 0.6 0.67 75 120 12840

36. Softwood 3.4 3.77 6.4 13 1644

37. Hardwood 5.8 6.44 8.95 16 2136

38. Wood stain/varnish 0.6 0.67 36 50 5350

39. Glass 0.25 0.28 12 15 1130

40. Aluminium (inwindows)

0.3 0.33 84 200 29200

41. Steel (in window 0.6 0.67 26 31 2441

42. UPVC (in windows) 0.6 0.67 75 120 12840

43. Rubber seals 0.6 0.67 93 150 16050

44. Mastic sealant 0.6 0.07 124 200 22200

45. Concrete screed 0.06 0.67 1.24 1.55 249

46. Nylon (in carpet) 0.6 0.67 118 190 20330

47. Polyester (in carpet)0.6 0.67 118 190 20330

48. Bitumen (in carpet) 0.6 0.18 39 50 5000

49. Wool (in carpet) 0.16 0.67 2 3 250

50. Rubber underlay 0.6 0.67 87 140 14980

51. Vinyl tiles 0.6 0.056 75 120 12840

52. Clay tiles 0.05 0.15 5.64 11.71 878


Table A1.4(continued)

Material/component Transport component ofembodied energy (GJ/t

Total embodiedenergy, includingtransport (GJ/t)


Deliveredenergy

Primaryenergy

Deliveredenergy

Primaryenergy

53. Terrazzo tiles 0.13 2.22 1.2 1.4 118

54. Marble 2 0.44 1.8 2 180

55. Mineral fibre tiles 0.4 0.28 30 37 2700

56. Ceramic fittings 0.25 0.67 10 20 1440

57. Brass pipework 0.6 0.67 75 120 11770

58. Copper pipework 0.3 0.33 90 137 8640

59. Steel pipework 0.54 0.6 30 35 2800

60. Stainless steelpipework

0.54 0.6 11 33 1518

61. Cast iron pipework 0.54 0.6 30 35 2800

62. Plastic 0.6 0.67 93 150 16050

63. PVC wire insulation 0.6 0.67 75 120 9652

64. Copper wire 0.3 0.33 100 152 9600

65. Brass 0.3 0.33 69 105 6555

66. Steel wire 0.54 0.6 28 35 2800

67. Lifts and escalator 0.56 0.62 28 35 2700

68. Natural stone 0.13 0.14 0.36 0.4 32

69. Reconstructed stone 0.13 0.14 1.2 0.4 118

70. Sheet aluminium 0.3 0.33 84 200 12321

71. GRP panel 0.6 0.67 71 100 8071

Life-cycle costing (LCC)Life cycle costing (LCC) or whole life costing is a method which totals the costs of aninvestment over a given study period. LCC is used to measure the economicperformance by considering:

• First cost

• Operational costs

• Replacement costs

• Residual value

• Study period

• Discount rate

Life-cycle assessment (LCA)Life cycle assessment (LCA) is a cradle-to-grave systems approach for understandingthe environmental consequences of technological choices. All stages in the life of amaterial generate environmental impacts that must be analysed and assessed. Theprocess involves:

• Definition of system boundaries

• Inventory analysis – identify/quantify all environmental inputs and outputs

• Impact assessment – characterise/relate the inputs and outputs

• Impact valuation – combine impacts with stakeholder values

• Improvement assessment – opportunities for making improvement to theproduct’s life cycle to improve its cradle-to-grave environmental performance

LCC and LCAIt is important to distinguish between the life cycles underlying LCC and LCA. LCA(used to measure environmental performance) uses an environmental life-cycleconcept. LCC (used to measure economic performance) uses a building life-cycleconcept. These are different.

The environmental life cycle of a building material begins with raw materialsextraction and ends with re-use, recycling or disposal of the material. The building lifecycle of a building material begins with its installation into the building and lasts forthe agreed duration of the study period (often 25 years). There is overlap while thematerial is installed in the building, but the two should not be confused. Two sets ofcalculations should be undertaken in order to balance environmental and economicperformance.

Balancing environmental and economic performanceConsider five options (A to E) of providing, say, window frames in a new building.Each option may be assessed in both LCC and LCA terms. (Fig B1)

Options D and E can easily be eliminated as having both higher life-cycle costs andworse environmental life-cycle burdens. But is it better to select option A (betterenvironmental performance but higher cost) or option C (lower cost but greaterenvironmental burdens)? Or perhaps something in between the two – option B – isbest. These LCC and LCA tools and procedures allow the client and designers to makeinformed choices.


Appendix B Life-cycle costing andlife-cycle assessment


A

B

C

D

E

Best Worst

Environmental burdens

Life

cyc

le c

ost (

£)

Fig B1. An example of a combined environmental and economic assessment


Appendix C Centres of excellence forsustainable constructionCentre for Sustainable Construction BRE

CIRIA ’93 SP3

Technology Foresight Panel – Industry Specific Sustainability Indicators

Construction Industry Environmental Forum

DETR

International Association of Hydrogeologists

BEPAC (Building Environment Performance Assessment Criteria), Vancouver,Canada

Wuppertal Institute Division for Material Flows and Restructuring (Director SchmidtBleek)

Product Life Institute Geneva (Director Walter Stahal)

Rocky Mountain Institute, Snowmass, Colorado, USA

Institute of Sustainable Development, Georgia Tech, Atlanta, USA