Essay: Could new build houses in the UK be carbon negative in terms of embodied energy?

MSc Architecture: Advanced Environmental and Energy Studies

Craig Embleton, 0750553, Group 1 (Melissa Taylor), C1 (Environmental Assessment, Management and Performance In Buildings) Essay

COULD NEW BUILD HOUSES IN THE UK BE CARBON

NEGATIVE IN TERMS OF EMBODIED ENERGY?

Word Count 2242

admin@greenfrontier.org

http://www.greenfrontier.org

For the attention of Melissa Taylor

July 6th 2009

Craig Embleton, 0750553, Group 1 (Melissa Taylor), C1 Essay admin@greenfrontier.org Page 1 of 48

Table of Contents

TABLE OF CONTENTS .............................................................................................. 2

INTRODUCTION ........................................................................................................ 3

CRITICAL ANALYSIS ................................................................................................ 4

CONCLUSION .......................................................................................................... 21

BIBLIOGRAPHY ...................................................................................................... 23

APPENDICES ........................................................................................................... 28

Introduction

This essay relates to the lecture ‘Environmental Impacts of Buildings’ of Module C1.

The Housing and Regeneration Bill ‘Supports the delivery of three million new

homes by 2020 … and …provides for the establishment of new settlements like eco-

towns’ (UK Parliament, 2008).

This could be enormously costly in terms of CO2 emissions. Energy used

constructing buildings is known as embodied energy. Harris and Borer describe

embodied energy as ‘the primary energy used in all the different stages of materials

processing’ (2005). It is measured in kilowatt-hours, Megajoules or, because there is

a direct relationship between embodied energy and CO2 emissions, CO2 per tonne of

material produced.

According to the Environment Agency, ‘About 10% of national energy consumption

is used in the production and transport of construction products and materials’

(2003). This industry emitted 53.21 millions tonnes of CO2 in 2008 (DECC2, 2009).

Much of this energy was used to build residential dwellings of which 223,300 were

completed in 2007 (CLG3, 2009).

There are, however, some materials used in construction, such as timber and straw

bales, that require little or no processing. These materials absorb atmospheric CO2

as they grow which then becomes incorporated into the structure of the house.

The aim of this essay is to investigate whether the amount of CO2 sequestered within

the natural materials used in the construction of a house can exceed that emitted in

the processing and transport of all the materials. It will calculate the embodied

energy (as CO2) of the author’s house using two methodologies and evaluate where

1 In 2008, UK net emissions of CO2 were provisionally estimated to be 531.8 million tonnes.2 Department of Energy and Climate Change3 Communities and Local Government

energy savings could be made and CO2 sequestered. It will compare the author’s

house to a high profile low impact build and also to best practice.

Critical AnalysisEmbodied energy (EE)Embodied energy can be measured as either the Process Energy Requirement

(PER) or Gross Energy Requirement (GER) of a material.

The PER is the energy related to material manufacture, including transporting raw

materials to the factory.

The GER is the PER plus:

• The energy used in the factories making the products.

• The embodied energy of the urban infrastructure (Milne G, 2008).

Investigations in this essay use figures for GER.

The Embodied energy of a UK House

Several studies have been performed which have attempted to calculate the

embodied energy of UK houses. The following studies used kWh as their common

units. Harris, D.J. carried out a case study on 'a typical British house design of the

type produced by a large builder': brick and block with mineral wool insulation and

aluminium window frames. The embodied energy contained in this building was

104,727 kWh4 (1999). Plastics accounted for nearly 45% of the embodied energy,

though the study does not explain why.

Brinkley, M. calculated the embodied energy of a detached brick-and-block house to

be 90,000 kWh (2006). Plastics formed only 12.44% of the embodied energy of the

build.

Asif, M. et al calculated the embodied energy of a Scottish three bedroom semi-

detached to be 59,0935 kWh (2005), with the concrete containing the highest

embodied energy. These studies are summarised in table 1.

4 kilowatt-hours5 Calculated from 212,719 Megajoules

Table 1. Summary of previous studies into embodied energy of UK houses

showing ten most energy intensive materials in each study. Full details are given in

appendices 1, 2 and 3.Study: Harris, D.J.

(1999)

Study: Brinkley,

M. (2006)

Study: Asif, M. et

al. (2007)Material EE

(kWh)

% Total

EE

EE

(kWh)

% Total

EE

EE

(kWh)

% Total

EEConcrete 13,800 15.2 36,336 61.5Concrete tiles 1,800 2.0

Concrete external

works

800 0.8

Plastics 47,000 44.9 11,300 12.4Bricks 6,348 6.1 27,100 29.8Ceramic tiles 8,956 15.2Timber 24,882 23.8 8,334 14.1

Steel 10,300 9.8 6,500 7.2Cement 8,580 8.2 6,000 6.6Mineral wool 2,433 2.3Clay tiles (roof) 2,052 2.0Aluminium 1,088 1.0 1,631 2.8Lightweight blocks 5,200 5.7Goods transport 5,000 5.5Plasterboard 3,200 3.5 1,500 2.5Glass 828 0.8 2,700 3.0 1,133 1.9Mortar 667 1.1Damp course 525 0.9

Slate 12 0.0Total 104,727 90,800 59,093Source: Harris, D.J. (1999), Brinkley, M. (2006) and Asif, M. et al. (2007)

Materials

The three builds varied in the amounts of materials used and the source data for

their embodied energy calculations. However, the studies indicated that minimising

the use of concrete and plastics in a house can reduce the embodied energy.

Carbon sequestrationAccording to the EPA6, ‘Carbon sequestration is the process through which

agricultural and forestry practices remove CO2 from the atmosphere’ depositing it

into carbon sinks. (2006). There are other carbon sinks too, such as the surface

waters of the oceans and types of rocks (Mackay, J.C.D, 2009).

Carbon cycles between land, ocean and atmosphere over biological and geological

timescales. One could conclude that all carbon sinks are temporary. Carbon

sequestered by trees felled hundreds of years ago has remained in the structure,

and furnishings of medieval timber-frame buildings. If these trees were replaced, the

net result has been a sequestration of atmospheric CO2 into terrestrial carbon. If the

buildings burnt down, of course, they would no longer be carbon sinks.

Embodied energy and carbon sequestration source material.This essay makes substantial use of the Inventory of Carbon and Energy (ICE). This

database collates embodied energy (MJ/Kg7) and (what the authors refer to as)

embodied carbon (kg CO2/kg) from an extensive range of sources. Where ranges of

values were listed for materials, this essay used the average.

Investigations in this essay use embodied and sequestered CO2 as a common unit to

enable calculations to be made.

Amato A (1996 cited in Hammond, G et al, 2008) argued against taking sequestered

CO2 from timber into embodied energy calculations, on the grounds that 'a material

is deemed renewable...when a world wide steady state has been achieved between

production and consumption'. He also argued that methane emissions from timber

disposal in landfill at end of life also needs to be addressed. For this reason

Hammond, G et al omitted carbon sequestration calculations from their Inventory of

Carbon and Energy (2008).

6 Environmental Protection Authority (USA)7 Megajoules per kilogramme

This essay also makes use of embodied CO2 data from the Green Guide to

Specification (the Green Guide).

Anderson, J. et al did include carbon sequestration within the LCA8 ratings they

presented in the Green Guide. The authors rated various building elements (ground

floors, upper floors etc.) against a set of environmental measures, including

embodied CO2 equivalent. The Green Guide specified a sixty year LCA. At the end of

this period it argued that most CO2 would be returned to the environment by landfill

or incineration. In the case of landfill, some of the carbon can remain sequestered

(2009).

Where a material’s density9 could not be ascertained from ICE, the websites

MatWeb.com and SIMetric.co.uk were consulted.

Methodology 1: Bill of quantities (BOQ) and embodied energy (EE) construction audit.

A BOQ contains, amongst other items, a list of all the materials required to construct

a building (BusinessDictionary.com, 2009).

8 Life cycle assessment9 Needed to convert from dimensions to weight

BOQ and EE construction audit for 32 Wentworth Close.

Figure 1. 32 Wentworth Close

A retrospective BOQ was created for the Author’s house: 32 Wentworth Close. This

is a brick-and-block, detached house built in 1975 with retrofitted, energy-efficiency

features, such as double-glazing, cavity-wall insulation and loft insulation. The

examination of embodied energy involved taking extensive measurements of the

house and referring to building manuals to estimate quantities of non-visible items.

The house was examined ‘as is’ rather than ‘as built’. Data from ICE and the Green

Guide were used to estimate the embodied energy.

The amount of CO2 sequestered in the timber of the house was estimated by

assuming that timber is 50% carbon10, and that the CO2 was sequestered indefinitely.

The full document is attached as appendix 4. The materials in this document were

then grouped in appendix 5, further summarised in table 2 and represented

graphically in figure 2.

10 The amount of carbon was multiplied by 3.667 to convert to CO2.

Table 2. Wentworth Close materials grouped.

Material Tonnes

material

kWhs Tonnes CO2

embodied

Tonnes CO2

Sequestered

CO2 Balance

(Tonnes)Concrete 59.7 15,767 7.8 0.0 0.0Brick 31.7 26,420 7.0 0.0 0.0Hardcore 83.7 9,300 4.7 0.0 0.0PVC-U Windows 0.0 23,647 4.3 0.0 0.0Steel 1.3 11,743 3.1 0.0 0.0Cement 2.6 3,301 2.1 0.0 0.0Lightweight

concrete block

23.2 4,316 1.7 0.0 0.0

Wood 2.9 6,512 1.4 5.3 -5.3Plaster/render 6.9 5,951 1.3 0.0 0.0Other materials 18.7 5,853 1.3 0.0 0.0U-PVC/Plastic 0.5 10,737 1.1 0.0 0.0Total 231.2 123,547 35.7 5.3 30.4Source: Anderson, J. et al. (2009), Automation Creations, Inc. (2009), Hammond, G. et

al. (2008), and Walker, R. (2009).

Figure 2 – CO2 embodied and sequestered in Wentworth Close

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

Con

cret

e

Bric

k

Har

dcor

e

PV

C-U

Win

dow

s

Ste

el

Cem

ent

Ligh

twei

ght c

oncr

ete

bloc

k

Woo

d

Pla

ster

/rend

er

Oth

er m

ater

ials

U-P

VC

/Pla

stic

Material

Tonn

es C

O2

Tonnes embodied CO2 Wentworth Close: Total = 35.7 tonnesTonnes sequestered CO2 Wentworth Close: Total = 5.3 tonnes

Source: Anderson, J. et al. (2009), Automation Creations, Inc. (2009), Hammond, G. et

al. (2008), and Walker, R. (2009).

BOQ and EE construction audit for Ben Law’s house.

Figure 3. Ben Law’s woodland house

Source: London Permaculture (2009)An oft-cited example of a low impact house is that built by the woodsman Ben Law

as seen on the television programme Grand Designs.

A BOQ was created for Ben Law’s house from information provided in his book The

Woodland Year. The embodied energy and sequestered carbon11 were calculated as

for 32 Wentworth Close.

The full document is attached as appendix 6. The materials in this document were

grouped in appendix 7, further summarised in table 3 and represented graphically in

figure 3.

11 The carbon content of wheat straw was estimated to be 34%.

Table 3. Ben Law’s house materials grouped.

Material Tonnes

Material

kWh

Total

Tonnes CO2

embodied

Tonnes CO2

sequestered

CO2

balanceLime putty 10.0 14,723 7.4 0.0 7.4Sandstone rubble 8.3 13,409 3.3 0.0 3.3Copper 0.7 3,980 2.7 0.0 2.7PVC-U 0.2 2,248 0.4 0.0 0.4Velux Windows 0.0 2,295 0.4 0.0 0.4Glass 0.2 994 0.2 0.0 0.2Particle board 0.4 947 0.2 0.7 -0.5Sharp sand 30.0 833 0.2 0.0 0.2Membrane 0.1 1,209 0.1 0.0 0.1Steel 0.0 283 0.1 0.0 0.1Other Materials 0.1 116 0.0 0.1 -0.1Oak 1.7 0 0.0 3.1 -3.1Barley straw bales 6.2 0 0.0 7.7 -7.7Larch 4.5 0 0.0 8.3 -8.3Sweet Chestnut 6.7 0 0.0 12.3 -12.3Total 69.1 41,037 15.0 32.2 -17.2Source: Automation Creations, Inc. (2009), Hammond, G. et al. (2008), Law, B

(2005), Walker, R. (2009) and Hammond, G. et al. (2008).

Figure 3. CO2 embodied and sequestered in Ben Law’s House

-15.0

-10.0

-5.0

0.0

5.0

10.0

Lim

e pu

tty

Sand

ston

e ru

bble

Cop

per

PVC

-U

Velu

x W

indo

ws

Gla

ss

Parti

cle

boar

d

Shar

p sa

nd

Mem

bran

e

Stee

l

Oth

er M

ater

ials

Oak

Barle

y st

raw

bal

es

Larc

h

Sw

eet C

hest

nut

Material

Tonn

es C

O2

Tonnes embodied CO2 Ben Law's house: Total = 15 tonnesTonnes sequestered CO2 Ben Law's house: Total = 32.2 tonnes

Source: Automation Creations, Inc. (2009), Hammond, G. et al. (2008), Law, B (2005),

Walker, R. (2009) and Hammond, G. et al. (2008).

32 Wentworth Close and Ben Law’s house contained115 and 113 m2 of floor space

respectively. 32 Wentworth close is a net source of 30.4 tonnes of CO2, Ben Law’s

house is a net sink of 17.2 tonnes.

Methodology 2: The Green Guide embodied CO2 audit of 32 Wentworth Close

This methodology uses only overall measurements of various sections of 32

Wentworth Close, such as the dimensions of external walls and ground floors in M2.

Estimations of the embodied carbon were then made by reference to tables in the

Green Guide.

As is.

The embodied CO2 of 32 Wentworth Close was calculated to be 28.9 tonnes, very

close to the 30.4 tonnes calculated for the house using methodology 1. This lower

figure is probably due to the fact that methodology 2 did not include fittings such as

the kitchen, pipe work or the electrical wiring in the house.

Reducing the embodied energy

Best practice using only new materials.

Using the Green Guide tables, the embodied CO2 of 32 Wentworth Close was

calculated, as if the house had have been built to best practice for embodied energy,

using, but without using recycled materials. Built like this 32 Wentworth Close would

contain only 0.87 tonnes of embodied CO2.

Best practice using some recycled materials.

Recycled materials are in limited supply, but are cited in the Green Guide tables.

The embodied CO2 in 32 Wentworth Close was calculated, as if the house had been

built to best practice for embodied energy, using recycled materials wherever

possible.

Built like this, 32 Wentworth Close would have been carbon negative, sequestering

1.6 tonnes of CO2.

Full details comparing the carbon balance of these three specifications are

presented in appendix 8, summarised in table 4, and represented graphically in

figure 4.

Table 4. Embodied Energy (EE) ofHouse section 32 Wentworth Close 'As is' Embodied

CO2 eq12

(Tonnes)

As if built to best practice standards for EE using new materials only

Embodied CO2 eq (Tonnes)

As if built to best practice standards for EE including reclaimed materials

Embodied CO2 eq (Tonnes)

External walls Brick of stone and blockwork cavity walls. Brickwork outer leaf, insulation, dense solid blockwork inner leaf: cement mortar, plaster, paint.

9.28 Cladding on timber-framed construction. Pre-treated softwood weatherboarding, breather membrane: OSB/3 sheathing, timber frame with insulation, vapour control layer, plasterboard on timber battens, paint.

-0.40 As best practice. -0.40

Ground floors Solid concrete floor. Screed on insulation laid on: in situ concrete on polyethylene dpm laid on blinded virgin aggregate sub-base.

6.77 Suspended timber ground floors. Tongue and groove softwood boards on timber joists with insulation over: 50 mm fine aggregate on polyethylene dpm laid on sand blinding.

0.00 As best practice, but with reclaimed floorboards.

-0.12

Windows and curtain walling

PVC-U window with steel reinforcement, double-glazed.

5.63 Durable hardwood window: Double-glazed, water based stain. (Timber Window Accreditation Scheme).

2.54 As best practice. 2.54

Landscaping (lightly trafficked areas).

Reinforced concrete laid in situ (100 mm): over prepared sub-base.

3.16 Cement mortar wet laid UK sandstone setts (50mm): over prepared recycled sub-base.

1.75 As best practice, but with reclaimed pavers

0.75

12 Equivalent

Internal walls Masonary partition. Aircrete blockwork: plaster, paint.

2.65 Timber studwork: plywood (softwood) unpainted

-0.55 As best practice. -0.55

Table 4 continuedHouse section 32 Wentworth Close 'As is' Embodied

CO2 eq13

(Tonnes)

As if built to best practice standards for EE using new materials only

Embodied CO2 eq (Tonnes)

As if built to best practice standards for EE including reclaimed materials

Embodied CO2 eq (Tonnes)

Roofs Pitched Roofs: timber trussed rafters and joists with insulation: roofing underlay, counterbattens, battens and concrete interlocking tiles.

0.94 Pitched Roofs: timber construction. Structurally insulated timber panel system with OSB/3 each side: roofing underlay, counterbattens, battens and photovoltaic roofing tiles.

0.11 As best practice, but with reclaimed clay tiles

0.03

Landscaping (pedestrian areas).

Concrete paving flags (35mm). No sub base * Reclaimed clay pavers = -8.7

0.49 Concrete paving flags (35mm).

0.49 As best practice, but with reclaimed clay pavers

-0.19

Insulation Cavity blown glass wool insulation: density 17 kg/m3

0.17 Strawboard thermal insulation.

-2.62 As best practice. -2.62

Landscaping (Boundary protection).

Hedging* embodied carbon as zero.

0.00 Pre-treated timber: Post and panel fencing.

-0.03 Reclaimed fencing. -0.10

13 Equivalent

Upper floors Upper floors. Tongue and groove floorboards on: timber joists * reclaimed floorboards on timber joists… = -18

-0.43 Upper floors. Tongue and groove floorboards on: timber joists * reclaimed floorboards on timber joists… = -18

-0.43 As best practice, but with reclaimed floorboards.

-0.96

Total 28.68 Total 0.87 Total -1.60

Figure 4. Tonnes embodied CO2 in Wentworth Close ‘as is’ and if Green Guide best

practice for EE had been implemented.

-4

-2

0

2

4

6

8

10E

xter

nal w

alls

Gro

und

floor

s

Win

dow

s an

d cu

rtain

wal

ling

Land

scap

ing

(ligh

tly tr

affic

ked

area

s).

Inte

rnal

wal

ls

Roo

fs

Land

scap

ing

(ped

estri

an a

reas

).

Insu

latio

n

Land

scap

ing

(Bou

ndar

y pr

otec

tion)

.

Upp

er fl

oors

Tonn

es o

f CO

2

Case study house. Total 28.68 tonnes

Best practice - new materials only. Total 0.87 tonnes

Best practice - some reclaimed materials. Total -1.6 tonnes

Source: Anderson, J. et al. (2009)

Straw bale buildingThe Green Guide advocated the use of strawboard in external walls to reduce

embodied energy and Ben Law’s house made extensive use straw bales for

insulation.

Straw is an abundant, renewable material. There are four million tonnes of excess

straw produced a year in the UK, enough to build 450,000 houses of 150m2 a year.

(Jones B, 2008): twice the number of houses constructed in 2007. Wheat straw

bales are approximately 34%14 carbon (Powlson, D.S. et al) and, if used as a building

material, sequesters CO2.

Building walls can be load bearing or non-load-bearing. The latter use straw bales

within a timber frame, and Tom Woolley suggests are more acceptable to the public

(2006). An innovative design, the ModCell™ Balehaus™, has been produced by

architecture practice White Design.

ModCell™ Balehaus™

Figure 5. ModCell™ Balehaus™ at Grand Designs Live 2009

Source: ModCell™ (2009)The ModCell™ system uses prefabricated straw bale panels, ‘made in a local Flying

Factory15™’, to create their Balehaus™ (2009). A frame of sustainably sourced

timber is in-filled with straw from locally sourced bales to form a ModCell™ panel.

These panels can be load-bearing or non-load bearing. In the former case they can

14 40% carbon by dry matter, equating to 34% carbon for typical bales of 15% moisture content15 Temporary structures built 5-25 miles from the house construction site.

be stacked 9m high. In the latter they are used as cladding panels within a timber-

framed building. In both cases the panel walls are plastered with lime render.

The company suggests that the carbon stored in the house exceeds that emitted

‘during manufacture, supply and installation of the building fabric, structure, fixtures,

fittings decoration mechanical and electrical equipment,’ by 6 tonnes16.

Source data was not available.

16 The text on the Modcell website actually says ‘This process “banks” the equivalent of 42 tonnes of CO2 per house to deliver a less than Zero Carbon Home before any one moves in. Even allowing for the ca 20 tonnes of CO2 emitted during manufacture, supply and installation of the building fabric, structure, fixtures, fittings decoration mechanical and electrical equipment, this still leaves 22 tonnes of carbon in the “bank”’. However the final figure should be 22 tonnes of carbon dioxide not carbon. 22 tonnes of CO2 is equivalent to 6 (22/3.67) tonnes of carbon. Verified via e-mail, appendix 9.

ComparisonThe CO2 balance of 32 Wentworth Close17, Ben Law’s house and the ModCell™

Balehaus™ are summarised below.

Figure 6. CO2 balance for 32 Wentworth Close, Ben Law’s house and the Modcell

house

CO2 balances (tonnes) for case study house, Ben Law's house and Modcell house

35.7

15.020.0

-5.3

-32.2

-42.0

-22.0-17.2

30.4

-50.0

-40.0

-30.0

-20.0

-10.0

0.0

10.0

20.0

30.0

40.0

32 Wentworth Close Ben Law's house Modcell house

Tonn

es o

f CO

2

Embodied CO2

Sequestered CO2

CO2 Balance

Source: Law, B. (2005), Modcell, (2009), Hammond, G. et al. (2008) and Anderson,

J. et al. (2009)

17 Calculated using methodology 1: Bill of quantities (BOQ) and embodied energy (EE) construction audit.

ConclusionSummary of case the madeIf material is selected from renewable sources, and CO2 assumed to be sequestered

permanently, it is possible to construct carbon negative buildings in the UK. If 32

Wentworth Close had been built to Green Guide best practice standards 2009, using

some recycled materials, it would have been carbon negative.

Ben Law’s house is carbon negative, but not designed for mass production.

The wide scale adoption of straw bales as infill for timber-frame builds and reducing

the use of plastics, concrete and brick greatly reduces the embodied energy. The

ModCell™ Balehaus™ showed great potential. Based on company data, the house

is substantially carbon negative.

Existing OrthodoxyMost housing energy studies concentrate on operational energy not embodied

energy. As operational energy efficiency of houses increases, the embodied energy

contributes a greater proportion to the overall lifetime CO2 emissions. The

refurbishment of existing buildings is often championed over new builds. However if

new builds are carbon negative, it may be better to replace some of the current

housing stock where it is difficult to lower the operational energy: e.g. if the houses

are not oriented to make best use of passive solar power.

Limitations of the essayThis essay was concerned with the embodied energy balance only, rather than full

Life Cycle Analysis or operational energy of houses.

It investigated single-family-unit residential dwellings, not business or multi-family

dwellings.

The essay did not consider changes in the carbon balance due to land use change.

Building on arable land may cause different changes in soil carbon to building on

pastureland or brown field sites.

The re-carbonation of lime over its lifetime was not included in the calculations, and

timber was assumed to be from renewable sources.

Further researchA full life cycle assessment of a ModCell™ Balehaus™ based on the BOQ method

employed for 32 Wentworth Close and Ben Law’s house would enable a more

accurate comparison of embodied energy.

Further work could investigate the scope for producing those materials that cannot

be ‘grown’, such as glass and metal, using renewable technologies. Investigations

into the production of plastics, used for items such as damp proof courses, from

biological sources should be investigated

Investigations into how the re-carbonation of lime affects CO2 balances should be

performed.

The suitability of car tyre foundations in domestic buildings, and other ways to reduce

the use of concrete should be investigated.

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Word Count –

AppendicesAppendix 1. Environmental profile for a typical brick-and-block house as

quantified by D. J. Harris.Material Quantity M3 Embodied

energy kWh

Percentage Total

Plastics 1 47,000 44.88Timber imported softwood 3.3 24,882 23.76Steel 0.1 10,300 9.84Cement 3 8,580 8.19Brick (Fletton) 21.16 6,348 6.06Mineral wool 10.58 2,433 2.32Clay tiles (roof) 1.35 2,052 1.96Aluminium (window frames) 0.0144 1,088 1.04Glass 0.036 828 0.79Concrete external works 1 800 0.76Copper 0.002 266 0.25Crushed granite external

works

1 150 0.14

Total 104,727 100Source: Harris, D.J. (1999)

Appendix 2. The Housebuilder’s Bible Benchmark House Construction Audit.

Material Energy /

tonne

(kWh)

Material

quantity

Weight

(tonnes)

Energy

used

(kWh)

C02

released

(tonnes)

Percentage

embodied

energyBricks 800 11,280 33.84 27,100 5.1 29.8Concrete 300 20 m3 46 13,800 2.6 15.2Plastic / u-

PVC

45,000 0.25 tonnes 0.25 11,300 2.1 12.4

Steel 13,000 0.5 tonnes 0.5 6,500 1.1 7.2Cement 1,500 4 tonnes 4 6,000 1.1 6.6Lightweight

blocks

300 172 m2 17.2 5,200 0.9 5.7

Goods

transport

5,000 0.9 5.5

Plasterboard 800 395 m2 4 3,200 0.6 3.5Glass 9,000 30 m2 0.3 2,700 0.5 3.0Other

materials

10,000 0.2 2,000 0.3 2.2

Concrete

tiles

300 112 m2 6 1,800 0.3 2.0

Hardcore

and gravel

30 60 tonnes 60 1,800 0.3 2.0

Timber

transport

1,500 0.2 1.7

Sanitaryware 5,000 0.2 tonnes 0.2 1,000 0.1 1.1Concrete

paving

300 20 m2 3 900 0.1 1.0

Sand 30 18 tonnes 18 500 0.1 0.6Chipboard /

plywood

300 2 m3 1 300 0.1 0.3

Timber 100 3 m3 2 200 0 0.20

Total 90,800 16.4 100Source: Brinkley, M. (2006)

Appendix 3. Embodied energy in a case study dwelling in Scotland.Material Quantity

(kg)

Embodied

energy (MJ)

Embodied

energy (kWh)

C02 released

(tonnes)

Percentage

embodied

energyConcrete 130,800 130,800 36,336 664.1 61.49Ceramic tiles 4,030 32,240 8,956 605,454 15.16Timber 5,725 30,000 8,334 178.4 14.10

Aluminium 25.3 5,870 1,631 48.1 2.76Plaster

board

1,080 5,400 1,500 3.5 2.54

Glass 313.6 4,077 1,133 2,301 1.92Mortar 2,400 2,400 667 286.2 1.13Damp

course

28.3 1,889 525 25.4 0.89

Slate 432 43.2 12 9,600 0.02Total 212,719 59,093 618,561 100Source: Asif, M. et al. (2007)

Appendix 4. Bill of quantities and carbon balance for 32 Wentworth Close.

Appendix 5. CO2 balance of materials contained in 32 Wentworth Close.Material Tonnes

material

kWhs Tonnes

CO2

embodied

Tonnes CO2

sequestered

CO2

Balance

Concrete 59.6 15,733 7.7 0.0 7.7Brick 31.7 26,420 7.0 0.0 7.0Hardcore 83.7 9,300 4.7 0.0 4.7PVC-U window with

steel reinforcement,

double glazed.

0.0 23,647 4.3 0.0 4.3

Cement 2.6 3,301 2.1 0.0 2.1Galvanised steel 0.7 7,135 1.9 0.0 1.9Lightweight

concrete block

23.2 4,316 1.7 0.0 1.7

PVC-U 0.4 8,375 0.9 0.0 0.9Plasterboard 1.8 3,290 0.7 0.0 0.7Render and plaster 4.8 2,411 0.6 0.0 0.6Steel 0.7 4,458 1.2 0.0 1.2Softwood 1.1 2,259 0.5 2.0 -1.5Ceramic 0.3 1,794 0.4 0.0 0.4Sawn softwood 0.7 1,360 0.3 1.2 -0.9mineral wool 0.2 1,055 0.3 0.0 0.3Wood 0.5 1,101 0.2 1.0 -0.7Copper 0.1 1,085 0.2 0.0 0.2Plywood 0.4 1,135 0.2 0.7 -0.4Polypropylene 0.1 1,437 0.1 0.0 0.1Chipboard 0.2 638 0.1 0.4 -0.3Clay 0.2 339 0.1 0.0 0.1Polyethylene 0.0 926 0.1 0.0 0.1Builders sand 12.1 335 0.1 0.0 0.1Stainless steel 0.0 149 0.1 0.0 0.1Cast iron 0.0 137 0.0 0.0 0.0Plaster (skim) 0.3 148 0.0 0.0 0.0Sand 5.7 157 0.0 0.0 0.0Lead 0.0 111 0.0 0.0 0.0

Appendix 5 continued. CO2 balance of materials contained in 32 Wentworth Close.

Material Tonnes

material

kWhs Tonnes

CO2

embodied

Tonnes CO2

sequestered

CO2

Balance

Concrete

(granolithic)

0.1 35 0.0 0.0 0.0

Hardwood 0.0 18 0.0 0.0 0.0Moulded plaster 0.0 8 0.0 0.0 0.0

Tiling grout 0.0 94 0.0 0.0 0.0Fibreglass 0.0 0 0.0 0.0 0.0Rockwool 0.2 839 0.2 0.0 0.2Total 123,547 35.7 5.3 30.4

Appendix 6. Bill of quantities and carbon balance for Ben Law's house.

Appendix 7. CO2 balance of materials contained in Ben Law’s house.

Tonnes

Material

kWh

Total

Tonnes

CO2

embodied

Tonnes CO2

sequestered

CO2

balance

Ash 0.0 0 0.0 0.0 0.0Barley straw bales 6.2 0 0.0 7.7 -7.7Beeswax and linseed oil 0.0 0 0.0 0.0 0.0Cheridised steel 0.0 43 0.0 0.0 0.0chicken wire 0.0 15 0.0 0.0 0.0

0.0 0 0.0 0.0 0.0Clay 0.0 0 0.0 0.0 0.0Clay, sand and straw 0.0 0 0.0 0.0 0.0Copper 0.6 10,910 2.2 0.0 2.2Copper (with polycarbonate

coating)

0.0 890 0.2 0.0 0.2

Copper sheeting 0.1 1,608 0.3 0.0 0.3Cow and horse hair 0.0 0 0.0 0.0 0.0Fibreboard 0.0 81 0.0 0.0 0.0Firebricks 0.0 0 0.0 0.0 0.0foam 0.0 21 0.0 0.0 0.0Galvanised steel 0.0 1 0.0 0.0 0.0Glass 0.2 994 0.2 0.0 0.2Glass wool and PIR foam 0.0 0 0.0 0.0 0.0Klober Permaforte 0.1 1,209 0.1 0.0 0.1Larch 4.5 0 0.0 8.3 -8.3Lime putty 10.0 14,723 7.4 0.0 7.4Lime wash and natural

pigments

0.0 0 0.0 0.0 0.0

Membrane 0.0 0 0.0 0.0 0.0Oak 1.7 0 0.0 3.1 -3.1Particle board 0.4 947 0.2 0.7 -0.5Pre-cast clay 0.0 0 0.0 0.0 0.0PVC-U 0.2 3,980 0.4 0.0 0.4Sandstone rubble 8.3 2,295 3.3 0.0 3.3Sharp sand 30.0 833 0.2 0.0 0.2Solder (lead) 0.0 0 0.0 0.0 0.0Stainless steel 0.0 162 0.1 0.0 0.1Steel 0.0 78 0.0 0.0 0.0Sweet Chestnut 6.7 0 0.0 12.3 -12.3Velux Windows 0.0 2,248 0.4 0.0 0.4Warmcell (Fireproofed

recycled paper)

0.1 0 0.0 0.0 0.0

York Stone Slab 0.0 0 0.0 0.0 0.0Total 69.1 41,037 15.0 32.2 -17.2

Appendix 8. The Green Guide to Specification CO2 balance for 32 Wentworth Close compared to best practice.