a planner's guide to carbon - 7-8-08

Lancefield Consulting Limited REALISING SUSTAINABLE DEVELOPMENT

A PLANNERS GUIDE TO CARBON

A PLANNERS GUIDE TO CARBON Page 2 of 25


UrbanBuzz

UrbanBuzz is a 2-year, 5m knowledge exchange impact programme in the broad subject area of building sustainable communities. It is led by University College London with the University of East London as its prime partner.

The programme has operated in a novel way by acting as an onward-funding mechanism, which has supported a wide range of projects and events, all of which represent collaborations between higher education institutions and public sector organisations, businesses and/or communities.

In total 27 projects have received funding (varying from 5,000 to 300,000+) and it is the aim of the UrbanBuzz programme to maximise the knowledge transfer legacy that can be leveraged from these projects. Some of the projects represent one-off events that will leave static outputs, where other projects have supplemented on-going research and development programmes and can be expected to have a natural continuance beyond the life-time of the UrbanBuzz funding programme.

The Planners Guide to Carbon arose out of a programme of training delivered by Lancefield Consulting to local authorities across London.

Lancefield Consulting Ltd

Lancefield Consulting is a technical planning consultancy, which provides guidance and advice to both public and private sector clients in relation to sustainable development in the built environment, sustainable design and urban design.

Over the last 3 years, Lancefield Consulting has produced Sustainability and Quality of Life Statements for leading developers (including Countryside Properties, Exemplar and European Land and Property Developments) in support of planning applications for major urban regeneration projects. In collaboration with Upstream (now part of JLL) Lancefield Consulting has also provided planning and development advice to the Berkeley Group, MEPC and Stanhope.

In 2007, Lancefield Consulting drafted a ground breaking Supplementary Planning Document for the London Borough of Barnet on Sustainable Design and Construction. Through 2007 and 2008, Lancefield has been providing training to planning officers at the GLA and the London Boroughs of Barking, Barnet, Islington, Kingston and Newham in the subject areas of sustainable and urban design.



CONTENTS

Introduction

Essential Knowledge

Code for Sustainable Homes, Merton Rule and the London Plan

Energy Statements

Energy Efficient Design

Energy Technologies

Combined Heat and Power

Solar Photovoltaics

Solar Water Heating

Heat Pumps

Biomass and Biofuels

Wind

Conclusions

Appendices

A - Table: Target and Design Carbon Savings

B - Jargon Buster and other useful information

C How much does it cost?

D What goes with what?



INTRODUCTION

This document provides Planning Policy and Development Control officers within local authorities with the bare minimum, absolute essential information that they need to know about energy in the built environment. The documents primary focus is to provide enough information to the Development Control officer to enable him or her to understand whether a planning application contains adequate information on energy and carbon emissions.

This document focuses mainly on residential development, but the general principles apply to all development types.

ESSENTIAL KNOWLEDGE - PHYSICS

Before engaging in any negotiations or discussions on energy and carbon, it is absolutely essential to appreciate that energy comes in two forms:

Light or Electrical Energy

Thermal Energy or Heat

Light or Electrical energy represents a higher quality of energy than thermal energy and can be easily converted into thermal energy. Thermal energy cannot, however, be converted back into electrical or light energy without significant loss of energy.

When produced from non-renewable resources (oil, gas or coal), light or electrical energy generates high carbon emissions, where thermal energy tends to generate lower carbon emissions.

The importance of this knowledge is that different technologies (renewable or non-renewable) deliver either electrical or thermal energy to a building. A gas boiler produces thermal energy. Photovoltaics and wind turbines produce electrical energy. Solar Water Panels produce thermal energy. Combined Heat and Power systems produce both electrical and thermal energy (albeit about twice as much thermal energy as electrical energy).

The usefulness of an energy source depends how it matches the energy requirements of the building heating, lighting or electrical power (power).

Authorship

This document has been prepared by Lancefield Consulting Ltd in collaboration with Urban Buzz. The Guide has been used in practice training sessions with the Greater London Authority (GLA) and the London Boroughs of Barking, Barnet, Islington, Kingston and Newham. Feedback from these training sessions has been incorporated into the document together with detailed criticism from the GLA, Professor Mike Davies (University College London) and Dr Rajat Gupta (Oxford Brookes University).



ESSENTIAL KNOWLEDGE ENERGY REQUIREMENTS OF BUILDINGS

The manner, in which buildings use energy, is generally considered as follows:

Heating maintaining the internal temperature above that of outdoors

Cooling maintaining the internal temperature below that outside (or preventing internal temperature rising because of internal heat sources such as IT equipment)

Hot Water that you use for baths, showers, etc

Lighting either natural lighting or artificial, powered from an electrical source

Power all those gadgets that we have in modern homes, from computers and kettles to washing machines and fridges

If you have a supply of electrical energy, then this can be applied to all the energy requirements of a building. Electrical energy can easily be used to power a radiator or air conditioning unit, to heat water, power the lights and supply energy to all those modern gadgets. But electrical energy drawn from the national grid is very carbon intensive.

If you have a gas supply to the house, then it can only be used for heating and hot water. In the case of offices, it can also be used to generate cooling. Unless you have a combined heat and power system, gas cannot be used for the lighting or to power those modern gadgets.

Each renewable energy type will generate either electrical energy or thermal energy and this dictates which aspects of the buildings energy requirements the renewable energy system can serve.

Consider your own home in the summer months: your energy consumption will primarily relate to hot water (for baths and showers) and power. There will be no heating, no cooling and, given the long daylight hours, little energy consumed in lighting. Your power requirements are strongly biased towards electrical energy.

KEY WORDS OR PHRASES

Merton Rule This is an approach to planning policy, seeking delivery of a percentage saving of carbon emissions (originally 10%) through the use of renewable energy technologies. It originated in the London Borough of Merton, but has now been adopted widely (see www.thermertonrule.org).

Building Regulations (Part L 2006) is the latest version of the building regulations, regulating the energy performance of buildings.



ESSENTIAL KNOWLEDGE POLICY AND REGULATION

The Building Regulations only address a proportion of all the energy consumed in a home or office: specifically, that associated with the installed energy systems.

The Merton Rule, as interpreted within the planning policy of most local planning authorities, represents making a saving of 10% (or now sometimes 20%) of the total carbon emissions from a development through the use of local renewable energy technologies. That is the full list above, including Unregulated Power. For modern houses, total energy consumption can be twice the regulated energy consumption.

(Some local planning authorities have accidentally worded their policy only to correspond to the Building Regulations component but not the GLA and not Merton be aware of the precise wording of your local policy.)

Whenever you consider an energy statement, then you must always check whether the calculations are based on Building Regulations only or the full energy consumption for the property.

The energy component for the Code for Sustainable Homes relates only to the Building Regulation quantity of energy (for Code Levels 1 to 5). There is consequently a mismatch between Building Regulations (and the Code) energy consumption calculations as compared to estimations required to meet Merton Rule criteria. Watch out for these!

Building Regulations Regulated Heating, Cooling, Ventilation and Lighting

boiler / heating / hot water cooling mainly offices building services fans, pumps, etc fixed lighting indoors and outdoors

_________________________________________________________________

Outside Building Regulations Unregulated Power

other plugged-in lighting and alarms (fire, security, etc) kettles, toasters, ovens, fridges, freezers and kitchen kit cleaning equipment dishwasher, washing machine, tumble dryer, hoover,

carpet/curtain cleaner IT equipment computers, tvs, hi-fi, printers recharging equipment cameras, telephones garden stuff lawnmower, hegde-trimmer, DIY kit, etc



CODE FOR SUSTAINABLE HOMES, MERTON RULE AND LONDON PLAN

The Code for Sustainable Homes, the Merton Rule and the London Plan all seek to reduce energy consumption in buildings. The London Plan approach is essentially the same as the Merton Rule (in principle), but relies on a more detailed step-by-step process to follow. Furthermore it now requires a 20% target, not 10%.

For all these approaches, the baseline starting point is the Building Regulations (Part L 2006). The Building Regulations rely on a complicated building simulation model, which provides a prediction for the regulated carbon emissions by a building. The Building Regulations provide a Target Emission Rate for standard building types (see Table in Appendix A). Hence the Target Emission Rate for a 4-bedroom detached house (assumed area of 140 square metres) is 21.2 kg CO2 per square metre per year. The Target Emission Rate for a mid-floor, 2-bedroom flat is 18.30 kg CO2 per square metre per year.

The actual design (Design Emission Rate) must achieve lower emissions than the Target Emission Rate. An engineer considering the energy performance of a building must start by estimating the Design Emission Rate for that building.

Code for Sustainable Homes

The Code defines more exacting targets for the regulated emissions. Hence, to achieve Code Level 3, the Design Emission Rate for the building must be 25% lower than the Target Emission Rate for that building type. Code Level 5 seeks 100% saving against Building Regulations (so the regulated component must sum to zero carbon emissions). Code Level 6 represents a step-change and seeks to achieve zero carbon emissions, taking into account unregulated power as well.

London Plan

The London Plan provides a stepped process to reducing carbon emissions:

Be Lean being as efficient as possible, primarily in relation to the regulated emissions (this equates directly to performance against the Code, if no Clean or Green technologies are incorporated)

Be Clean seeking to generate energy locally through more carbon efficient technologies, such as combined heat and power (equates to Code performance, if no Green technologies are included)

Be Green seek to deliver a 20% reduction in the final carbon emissions (after applying Lean and Clean) through use of renewable energy technologies (essentially a Merton Rule, but factoring in required prior consideration of Clean technologies).

The London Plan also provides a hierarchy of Clean technologies to consider in a deemed order of merit, based on their normal contribution to improved building performance; these are summarised in the Appendix B.



ENERGY STATEMENTS (ENERGY DEMAND ASSESSMENTS)

You should expect the following general methodology for any energy statement.

a. Building Regulations Estimate. Statement of the annual carbon emissions associated with the Building Regulations components of the building. This represents the typical target rating for a building of the type being considered (detached house, semi-detached or a flat). (Target Emission)

b. Energy Efficient Design Features (Be Lean and Be Clean). Identification of design features (including improved insulation, better air tightness, centralised boiler plant and combined heat and power technology) which will improve upon the Building Regulations calculation and which will lead to a score under Energy within the Code for Sustainable Homes. (Design Emission and Code score).

c. Power Calculation. Addition of Power consumption estimate. There is a method for calculating Unregulated Power within the Technical Guide for the Code for Sustainable Homes for Code Level 6.

d. Total Carbon Emissions. B plus C should provide a total estimate of carbon emissions for the building, which should be split between thermal and electrical energy components. In more sophisticated energy statements, the variation of energy consumption over the year will also be shown.

e. Renewable Technologies. The remainder of the energy statement should seek to match appropriate technologies to the energy consumption patterns (thermal and electrical energy) of the building and its occupants, aiming to meet the 10% or 20% criteria. This final calculation represents the Merton Rule calculation (and also relates directly to the requirements in the London Plan).

Throughout all energy statements, you should require planning applicants to provide estimates of the total carbon dioxide emissions per year for the household (or average for the households) units given in tonners of carbon dioxide per year for each dwelling. This enables comparison against rules of thumb (see next section).

Energy Statements Caveat

When an engineer is developing an energy strategy, they will not follow the precise process set out above; but they will be able to explain their approach in accordance with the above structure. To meet the final Merton Rule requirements, the engineer must address the whole building energy requirements from the outset in order to achieve an optimal carbon saving strategy. Most power requirements of a building are for electrical energy, which changes the balance of electrical to thermal energy and might dictate a different final energy solution than if the regulated energy (Building Regulations component) were considered separately.

Recognising this difference between Code for Sustainable Homes performance and Merton Rule requirements, the GLA SPG on Sustainable Design and Construction only requires an explicit baseline as (a) above (Target Emission Rate) and not any explicit statement of the final Design Emission Rate. Rather under the GLA guidelines, steps (b), (c) and (d) tend to be consolidated into one single step.



ENERGY EFFICIENT DESIGN THE PLANNERS PERSPECTIVE

Achieving a low carbon building is a technical engineering challenge and no planner can or should be expected to understand the detail. Many of the issues are beyond the scope of direct consideration under the planning system (such as what insulation is used, the insulation performance of the windows or the air tightness of the building).

But there are some areas, where a planner can use his or her common sense to identify spurious claims by planning applicants and which could reasonably be expected to be addressed during the planning process.

Rules of Thumb Numbers to Know

The average household carbon emission for the UK is approximately 6 tonnes carbon dioxide per year. This includes both new and existing dwellings. Modern dwellings should significantly improve on this average.

The range of figures for new dwellings that you should keep in mind are as follows:

Likely Worst Case Scenario - Detached House (4 bedrooms of floor area 140 sqm) just meeting the Building Regulations minimum (Part L 2006) with a predicted occupancy of 2.8 will consume in the order of 4.4 tonnes of carbon per year. (The Building Regulations component of this sum is 3 tonnes per year and the Power component is 1.4 tonnes (about 30%).)

Likely Better Case Scenario - Mid-Level Flat (2 bedrooms of floor area 50 sqm) achieving Code Level 4 against the Code for Sustainable Homes and with a predicted occupancy of 1.8 people will consume in the order of 1.3 tonnes of carbon per year. (The Building Regulations component of this sum is 0.5 tonnes per year and the Power component is 0.8 tonnes (unregulated power now exceeding regulated carbon emissions.)

A table is provided in Appendix A with a breakdown of these calculations.

Using these numbers, it can be deduced that:

To meet a 10% Merton Rule, the Detached House meeting Part L only will need to generate the equivalent of 0.44 tonnes of carbon saving per year.

To meet a 10% Merton Rule, a block of 10 flats built to Code Level 4 will need to generate the equivalent of about 1.3 tonnes of carbon saving per year.

Remember: You should make sure that energy statements provide figures which explicitly state the predicted emissions in tonnes of carbon dioxide generated per year. If an energy statement shows numbers that veer significantly away from the above Rules of Thumb, then a planning officer should seek further clarification.



Remember that in an energy statement these figures should be broken down according to thermal and electrical energy and the renewable energy technologies chosen to match the energy requirements of the building.

Location

The average generation of carbon dioxide per car in the UK is about 3 tonnes per year. This is half the average household (dwelling only) emission of carbon dioxide. New flats now produce considerably less carbon than the average car.

For much new build, transport represents the major factor generating carbon emissions per household.

So, do not forget the critical importance of transport towards generating carbon emissions location and access to amenities is critical.

Energy Supply

Non-renewable energy delivered to a building tends to come in two forms: electricity or gas (or sometimes oil instead of gas).

Electricity is a highly refined energy product, for which over 40% of the original energy is lost by the time the electricity reaches the household. Gas delivered directly to a household is much more efficient. But unless the gas is burnt using combined heat and power, then it can only generate low quality energy (heat).

Any reduction in the use of electrical energy drawn from the national grid achieves a proportionately larger reduction in carbon emissions than the same reduction in use of gas.

Orientation and Facade

The orientation of a property will have a very significant impact on its carbon performance, at least in relation to heating and cooling. Large south facing windows will capture sunlight and heat the building up like a greenhouse, leading to discomfort or the need for air conditioning (especially for modern, well-insulated buildings).

The quantity of windows in a property will strongly dictate its carbon performance. Even the best double and triple glazed windows are an order of magnitude worse at insulating a building than the walls and roof.

So, when you are considering planning applications, you should watch out for the following:

A large proportion of the faade glazed. More than 25% and you should become suspicious that it may struggle to meet Building Regulations, leave alone achieving improvements on the Building Regulations.



Large south-facing windows should be avoided, unless they are accompanied by shading mechanisms.

Ventilation

When considering flatted developments, beware the single aspect flats. The same aspect flat located on the north side of a building verses on the south side of the building will have hugely different levels of internal comfort, particularly during the summer months. This may imply a reliance by the designer on cooling technology, even if this is not explicit elsewhere in the application. Generally speaking, cooling in residential properties should be deemed unnecessary in the UK climate. Good design should enable avoidance of this extra energy consuming practice.

Single aspect flats cannot be cross-ventilated (in other words having a window open at the front and the back). For deep flats, this means that active ventilation will be required at the back of the property. If this is the case, then the designer should be incorporating heat recovery within the ventilation to counter the carbon emissions associated with the active ventilation.

Other Terminology

You should not be phased by other terminology: for example, U-values, Air Tightness, Thermal Mass and Thermal Bridging.

U-Values relate to the level of insulation of a building and dictate the rate of heat loss through the buildings faade (walls and windows), roof and walls. The lower the U-value the better, indicating reduced heat loss.

Air-tightness relates to the draftiness of the building. A value of around 10 is what is expected within the Building Regulations.

Thermal Mass represents the capacity of a material to store and retain heat (or coolth). This is different to insulation, which simply prevents conduction of heat through itself but does not itself have the ability to store heat or coolth. A building with high thermal mass can help to average out the day/night fluctuations in outdoor temperature.

Thermal Bridging arises when materials that are poor insulators come in contact, allowing heat to flow through the path created. For example, structural steel beams will represent a good path of conduction of heat. Thermal breaks are required to prevent the heat being conducted away.



PLANNING NEGOTIATIONS AND PLANNING CONDITIONS

Code for Sustainable Homes verses the Merton Rule

There is a large discrepancy between the Code for Sustainable Homes and application of the Merton Rule. Throughout the whole Code calculation (out of a total of around 100 points), only 1 point is awarded for use of any renewable technologies. Normally there will be a much cheaper way to win Code points. Only above Code Level 4 does it become essential to look to renewable energy technologies to achieve sufficiently low design emissions.

To meet a 10% Merton Rule (taking Power into account) can cost millions of pounds for even relatively small developments. Furthermore, it can be very difficult to condition and check that a constructed building does indeed meet the aspirations within the planning application or secured through negotiation.

For example, a planning officer will have to rely entirely on trust that a planning applicant has installed the correct surface area of sufficiently high performing photovoltaics, or that the right type of boiler has been installed, or that the wind turbine really does generate the required carbon savings. Most planning authorities do not have the resources to check whether such conditions or obligations have been adequately met (certainly not for small to medium developments).

In negotiations a balance has to be found between a high Code score verses a high (or any) Merton Rule percentage of renewables. In the case of the Code, a system is in place to enable a planning authority to require certification. If this is achieved, then (though it only relates to the regulated energy consumption) at least a defined improvement in energy efficiency has been secured. In contrast, without very complex planning conditions or S106 obligations, any percentage agreed against the Merton Rule has a high chance of never being secured.

In practice, to be sure of making a carbon saving, in many instances and particularly for smaller developments, it is probably better to aim for a higher Code scoring and sacrifice the Merton Rule.

Code for Sustainable Homes Planning Conditions

It is useful to be aware of how the Code operates. Practically there are three stages to assessment.

1. A pre-estimation that will accompany a planning application. 2. A design stage accurate estimate prior to construction. 3. A certification stage, post completion.

In practice the last point that planning will be able to influence designed outcome is at Stage (2). It is therefore critical that the relevant planning condition has two stages requirement to present the pre-construction estimate and then the final certificate.



ENERGY TECHNOLOGIES - OVERVIEW

The following represents a short summary of each of the key renewable energy technologies, providing key rules of thumb to watch out for.

Centralised Boiler Plant and Combined Heat and Power

Description

There are various technological options available which centralise the energy generation within a development. These can vary in scale from a single gas boiler in the basement of a block of flats, replacing individual boilers in individual flats, through to a district system serving several or numerous buildings and in which both heat and electricity are generated (combined heat and power).

Generally speaking any centralisation within a development will deliver energy efficiency improvements against individual units in houses or apartments.

Where electricity is also generated (combined heat and power (CHP)), then significant improvements are attained because of the off-setting against grid-delivered electricity, which as stated earlier is very carbon intensive because of the energy lost in distribution.

Type of Energy Used and Generated

Centralised boiler systems only produce thermal energy. CHP systems produce both heat and electricity.

All such systems can draw on either non-renewable energy (gas or oil) or renewable energy sources (biomass or biofuel see later). But beware, there are very, very few examples where CHP and biomass have been used successfully to-date. Any proposals suggesting biomass powered CHP should be treated with suspicion unless very reputable service engineers are involved.

Without biomass or biofuel, CHP is NOT a renewable energy technology: just a carbon efficient technology.

Constraints, Limitations and Conflicts

CHP systems produce roughly twice as much heat as they generate electricity. To be viable economically they require a large and constant demand for heat. This can sometimes make their application to energy efficient new housing problematic. Current insulation standards mean the requirement for space heating is very low and demand is present for only part of the year. The only constant source of heat demand is for domestic hot water and in terms of reducing CO2 emissions much of this demand could be met by the use of solar water heating instead (certainly in low rise dwellings).



For CHP systems to be economically viable they need to run for at least 4,000 hours per year. They are more suitable for leisure centres with swimming pools and hospitals that have a high, year round heat demand or in mixed use developments with a suitable heat demand distribution across the building types. (Note: cooling demand equates also to heat demand because the thermal energy from the CHP can be easily converted to provide cold water for cooling.)

Typical Quantities of Carbon Saving

Well-design CHP systems can achieve up to 30 to 35% carbon savings in a development. If a system is designed to meet electricity demand, it will produce spare heat, which could supply other nearby developments.

Typical Costs

The cost of CHP plants depend on the site, local requirements and the machine installed. Costs of the actual units can range between 500 and 2,000 per kW of electrical output. A good mid-range estimate is 900 per kW hence a 50kW system would cost 45,000 and a 5MW system would cost 4.5m.

As a rule of thumb, for residential CHP systems will be sized to provide around 30kW of electrical output per 100 residential units. Based on the above, a CHP system for 100 units would cost around 27,000. Note that commercial and retail floorspace can consume considerably more and quickly lead to much larger units than one sized for residential only.

But the CHP unit itself may represent only a minor proportion of the overall cost. The other costs include the centralised plumbing through the building and the heat exchange units within properties. These costs have been estimated to equate to around 5,000 per dwelling (between 3,000 and 6,000). But if the developer planned at the outset to have some form of centralised hot water system (such as a centralised boiler), then the cost of converting to CHP will be relatively small.

It is important to recognise that combined heat and power schemes below 300 or 400 dwellings are unlikely to be cost effective to a commercial developer. Smaller schemes have to date only proven cost effective where public sector discount rates and project lifetimes of over 20 years are used.

For smaller developments of 100 homes or less, (typical of infill projects) densities may need to be around 75 dwellings per hectare to be cost effective.

Capital Costs verses Operational Costs

A major benefit of CHP systems is that they lead to significant cost savings for occupants of dwellings. However this is achieved through a much higher up-front capital cost to the developer. Unless a developer is likely to find a way to recoup this money, there is a strong disincentive to go down this route.



Solar Photovoltaics

Description

Otherwise known as PVs, these are tiles that generate electricity. Ideally they are placed on a south-facing 30-40 degree surface (roughly equivalent to a normal pitched roof), but they can also be placed on (almost) flat or vertical surfaces. PVs are now being designed to be very unintrusive and can even now replace glass (for instance, installed as roof of a conservatory).

PVs vary significantly in their efficiency from the highest quality to the lowest quality of panels. They are specified according to kWp (peak output).

Type of Energy Generated

PVs use sunlight to generate electrical energy.


While prices are reducing all the time, the main limitation is that they still cost a great deal for the quantity of carbon saving achieved.


8m2 (2m x 4m) of High Efficiency PVs will generate approximately 750 kWh/yr. If this is used to offset the use of electricity in a building, then this equates to about 0.43 tonnes of carbon per year.

The Detached House example noted earlier would need little more than 8m2 of high efficiency panels to achieve a 10% carbon saving. For Low Efficiency PVs, an area of around 24m2 may be required (6m x 4m, which may be more than the south facing roof area).

The block of 10 flats example noted earlier would require 24m2 of high efficiency panels to achieve a 10% saving.

Typical Costs

According to the British Photovoltaic Association, the cost of installing PVs is approximately 6 to 7 per Wp. On this basis, the cost to achieve the 10% carbon saving for the detached house would be circa 8,000 to 10,000. The cost to achieve the 10% carbon saving for the block of 10 flats would be 28,000 to 32,000. When being installed in new build, the above figures should be marginally reduced.

Very approximately, cost is 20,000 for each tonne of carbon saved per year. While high efficiency PVs cost more per square metre, when considering carbon savings low efficiency and high efficiency PVs are cost equivalent. Choice of high efficiency verses low efficiency is a design, not a cost, issue.



Solar Water Heating

Description

Solar Water Panels use energy from the sun to heat water. The hot water is stored in a hot tank. These systems can operate successfully in diffuse light conditions (clowdy) and will generate hot water all the year round. Ideally they are placed on a south-facing 30-40 degree surface (roughly equivalent to a normal pitched roof), but they can also be placed on (almost) flat or vertical surfaces.

Solar Water panels are much more visually intrusive compared to PVs.


Solar Water panels generate hot water (thermal energy).


They cost much less than PVs. Care needs to be taken as to what other renewable energy technologies are selected. Technologies such as Combined Heat and Power tend to produce excess heat, which can be used to heat water. In which case, Solar Water Panels provide no added benefit.

The degree of benefit associated with Solar Water panels depends very much on water use patterns and they work best where hot water is required during the day, such as when buildings are occupied by elderly or young families.


The standard domestic system (2 metres x 2 metres = 4m2) reduces C02 emissions by around 0.35 tonnes per year (Energy Savings Trust) and will provide about a third of hot water needs for a household0.

To achieve a 10% annual carbon saving, the Detached House example would need 5m2 of panels. The 10 Flats would need 15m2 for all the flats.

Typical Costs

A standard household system (area of 4m2) will cost between 2,500 and 4,000.

The approximate cost for the Detached House would be 3,000 - 5,000. The approximate cost for the Block of 10 Flats would be 9,000 - 15,000.

Very approximately, cost is 7,000 - 11,000 for each tonne of carbon saved per year.



Heat Pumps

There are two fundamentally different types of Heat Pumps: ground source heat pumps (GSHP) and air source heat pumps (ASHP). Both use refrigeration technology to convert a small temperature difference from a large volume (the air or the ground) to create a large temperature difference in a smaller volume. This larger temperature differential can then be used to cool or heat the air in a building.

Ground Source Heat Pumps

Description

These are used to extract heat or coolth from the ground to provide space and water heating or cooling. The Heat Pumps take in heat at a certain temperature and release it at a higher temperature, using the same process as a refrigerator. The main variations on the core technology are:

Horizontal or Vertical Pipe distribution underground. Horizontal need a large area of space (e.g. a car park). A single house would require around 100m2 (10m x 10m). The vertical need to be placed in (potentially) deep bore holes.

Open or Closed. The Open systems extract water from the ground and either return it or discharge to the sewer. The Closed systems re-circulate the same water within closed pipes.

Water Bodies. Where a river, canal or lake lies proximate to a development then a closed or open loop system can be used with this surface water.


GSHP consume electricity but generate hot or cool water (thermal energy). When effective they produce 3 to 4 times more thermal energy than electrical energy consumed.


GSHP are not generally suitable for single dwellings. Compared to efficient gas boilers, they achieve little by way of reduction in carbon emissions, for considerable extra cost and risk. They come into their own when cooling is required, for retail or offices. Open systems are much more effective, but require a permit to extract water from the ground. Technical feasibility must be determined through testing. Highly skilled input is required to achieve good results.

This solution conflicts with Solar Water Panels and Combined Heat and Power.

Given the technical expertise required, a planning officer should remain sceptical unless a respected consultancy has been engaged to carry out the analysis and provided the recommendations and determined the likely carbon savings.

Treat with extreme care.




This varies significantly upon type of system installed and expertise used to design and install. Where a system provides for all heating and hot water requirements, then it could save up to 3 tonnes per year. It will only achieve highest carbon savings if the heat pumps do not rely on electricity from the national grid. In this respect, they operate well in conjunction with Photovoltaics.

Typical Costs

It is generally considered that a good rule of thumb is 1,000 - 2,000 per kW capacity. A typical residential system of 6 - 8kW costs 8,000 - 12,000. This indicates a capital cost of 3,000 to 4,000 per tonne of carbon dioxide per year.

Air Source Heat Pumps

Description

In air-source heat pumps, external air at ambient temperature is cooled or heated by passing over a finned heat exchanger. As with GSHP, they can be used to both heat and cool a building. ASHP are most efficient when supplying low temperature distribution systems such as underfloor heating. These pumps are particularly cost effective in areas where mains gas is not available.


As with GSHP they deliver thermal energy only.


The technology is relatively new and while still rapidly evolving, they are currently less efficient than GSHP. Their performance may be variable because of day night variations in air temperature. This is why they operate best with low temperature distribution systems. They operate very efficiently in conjunction with Photovoltaics, albeit they need to be backed up by grid electricity supply.


A typical domestic system could provide for all the space heating requirements in modern well insulated dwellings, providing circa 1 to 2 tonnes of carbon saving per year.

Typical Costs

An ASHP typically costs in the region of 3,500 (6kW) and 6,000 (12kW), excluding the cost of the distribution system (eg. radiators). This represents a capital cost of circa 2,000 to 3,000 per tonne of carbon saved per year.



Biomass and Biofuels

Description

Biomass or biofuels are at best carbon neutral as the carbon emitted on burning has been recently absorbed from the atmosphere through growth of plants. However most planning authorities will accept these fuel sources as being renewable. There are two contrasting methods of using biomass heating in housing: single room heaters and stoves or centralised boilers. Biomass can be used to power CHP systems; but there are very few examples of this being done successfully to-date.


Except in the circumstance of a biomass fuelled CHP system, biomass systems only generate thermal energy.


The most significant constraint is the sourcing of the fuel, delivery and storage. The degree of carbon saving achieved depends upon the distance travelled and the level of refining of the fuel required. In buildings, Biofuels, which are highly refined fuels (biomass equivalent of petrol), generally do not provide any carbon savings compared to gas. They should not therefore be accepted, unless rigorously assessed for appropriateness.

These systems all require significant levels of maintenance and cleaning and need management in place to ensure this happens. Because of the maintenance, 100% back up systems (normally a standard gas boiler) must be installed.


Biomass boilers can easily cover all the heat requirements of a building, but without CHP will not meet any of the Power (electricity) demand.

Typical Costs

The capital cost of a biomass boiler will typically be 2,000 for an individual house rising to 30,000 for a block of flats or office. This is only marginally more than the gas equivalent. It is a very cheap way (in terms of capital costs) for developers to achieve significant carbon savings according to Merton Rule requirements.

It is unlikely that occupants will see any cost savings from the use of biomass boilers as the fuel is very likely to be comparable in cost to other fuels, if not more expensive. In addition there are the extra maintenance requirements.

Beware Because of the Building Regulations requirement for a back-up system, many more opportunistic developers agree to install a biomass boiler with the full intention of never using it.



Wind

Description

Wind turbines come in all shapes and sizes: the larger, the more effective and efficient. Very small wind turbines in urban areas have been referred to as Eco-bling because they deliver very little (if any) benefit. Wind turbines vary in rating from 600W (1.7m diameter blades) to 3.5MW (blades bigger than Jumbo jet wings).


Wind Turbines generate electrical energy.


Good wind conditions are required, preferably not turbulent from neighbouring properties. Average wind speed for a location has a huge impact on the output of the wind turbine.

Visual intrusion is the key planning concern. The ideal position of a wind turbine is to be high and clear of obstructions, which tends to be entirely counter to visual planning considerations.

Noise is often raised as a concern, but in modern wind turbines does not tend to be an issue. If poorly installed on buildings, they can lead to vibration nuisance.


The annual output from a 600W (normal residential size) turbine can vary from 800 kWh/yr up to around 3,000kWh/hr. When converted into carbon savings, this range represents a potential saving of between 0.45 tonnes carbon per year up to 1.7 tonnes of carbon per year. In urban areas, the lower end of this range is more likely.

For the Building Regulations compliant Detached House example, this should mean that most, if not all, electricity requirements were met and provide for a sizeable carbon saving (well in excess of 10%). For the Block of 10 Flats built to Code 4, the upper end of this spectrum would meet the required 10% Merton Rule target.

Typical Costs

A 600W turbine will cost of the order of 3,000.

Very approximately, cost is 5,000 or less for each tonne of carbon saved per year. It is a very good solution if the environmental conditions are right and if it is acceptable in planning terms. But beware over-estimates on level of windiness, particularly in built-up areas.



CONCLUSIONS

These are some of the key issues to be wary of:

EXAGGERATION: It is in the interest of the whole supply chain within the construction industry to exaggerate the performance of renewable technologies. If in any doubt, make sure that the figures are corroborated by a reputable services engineer.

ENERGY EFFICIENCY: Houses built to Levels 3 and 4 of the Code are already very high performing dwellings which need very little space heating. The increasingly significant factor defining energy consumption is the lifestyle and gadgetery of occupants. This is driving the Building Regulations (and consequently Code Levels 1 to 5) further and further apart from Merton Rule solutions.

TRANSPORT: In highly rated dwellings, energy consumption in private vehicles becomes a very significant component (much more than 50%) of the household carbon emissions. The PPS Supplement on Climate Change places an onus on planning to limit or mitigate this. Planning applicants should at the very least provide transport related carbon estimates in energy statements or transport assessments.

CODE FOR SUSTAINABLE HOMES: Beware that just because a dwelling meets a high Code Level, it does not mean that it performs well across all issues. Factors such as internal noise and lighting are often sacrificed and points scored elsewhere.

CODE FOR SUSTAINABLE HOMES AND CHP: As a general rule of thumb, if a building is designed to Code Level 3, then the addition of CHP alone will take its rating up to Code Level 4.

TRICKS OF THE TRADE: Beware the developers who:

suggest Biomass or Biofuel and then never turn on the boilers (or even never install them)

remove the A+ Rated White Goods from dwellings after Code or Ecohomes assessments

propose technologies that do not exist, such as dual-fuel biomass CHP units!

LOOKING GREEN: Just because it looks green does not mean that it is green.

KEEP IT SIMPLE: Technologies such as Solar Water Panels may appear less sexy, but they have their place and are often better long-term solutions than more complicated strategies.

STICK TO CARBON: Make sure that energy statements are consistent in their figures throughout ask for all subtotals and totals to be given in tonnes of carbon dioxide per dwelling per year so that you can compare these to the rules of thumb.



APPENDIX A - A PLANNER'S GUIDE TO CARBON

Bedrooms Floor Area Assumed BR Part L Power(sqm) Occupancy Target Part L Code 3 Code 4 Component Part L Code 3 Code 4

Emission Code 6**(kg/m2) (tonnes of C

(0%)* (25%)* (44%)* per yr)

Detached House 4 140 2.8 21.2 3.0 2.2 1.7 1.4 4.4 3.6 3.1

Semi-detached House 3 120 2.8 21.9 2.6 2.0 1.5 1.3 4.0 3.3 2.8

Mid-terrace House 2 64 2.3 21.6 1.4 1.0 0.8 1.0 2.4 2.0 1.8

Top Floor Flat 2 50 1.8 20.8 1.0 0.8 0.6 0.8 1.8 1.6 1.4

Mid-Floor Flat 2 50 1.8 18.3 0.9 0.7 0.5 0.8 1.7 1.5 1.3

Ground Floor Flat 2 50 1.8 21.7 1.1 0.8 0.6 0.8 1.9 1.6 1.4

* Required Savings for Designed Emission (final building design) against Target Emission** Taken from Appliances and Cooking Estimator for Code 6 within Code for Sustainable Homes Technical Guidance

Photovoltaics Calculation

8m2 of High Efficiency PVs will generate in the order of 750 kWh/yr.The Conversion Factor to estimate Carbon Savings when Electricity is being displaced is 0.568 kgCO2/kWh.The Carbon Saving provided by 8m2 of High Efficiency PVs will be (750 * 0.568) = 0.43 tonnes of carbon per yearEach m2 of High Efficiency PVs achieve approximately 0.05 tonnes of carbon saving per year

Solar Water Heating Calculation

Annual Carbon Saving associated with standard domestic array of Panels (4m2) is 0.35 tonnes carbon per yearEach m2 of Solar Water Panels can be expected to generate a saving of approximately 0.09 tonnes of carbon saving per year

Wind Calculation

Annual electricity generated from a 600W (1.7m diameter) turbine varies between 800 kWh/yr and 3,000 kWh/yrThe Conversion Factor to estimate Carbon Savings when Electricity is being displaced is 0.568 kgCO2/kWh.The lower Carbon Saving provided by a 600W turbine would be around 0.45 tonnes of carbon per yearThe higher potential Carbon Savings provided by a well located 600W could be up to 1.7 tonnes of carbon per year

(Annual Tonnes of Carbon)

BR Annual Carbon

(Annual Tonnes of Carbon)

Total Annual Carbon

(Merton Rule relevant figures)(BR and Code relevant figures)



APPENDIX B - JARGON BUSTER

Air-tightness relates to the draftiness of the building. A value of around 10 is what is expected within the Building Regulations. Building Regulations (Part L 2006) - This is the latest version of the building regulations, regulating the energy performance of buildings. Next revision due in 2010. Carbon verses Carbon Dioxide All reference to carbon throughout this document should be deemed to mean emissions of carbon dioxide and mass of carbon dioxide emitted (eg. tonnes of carbon dioxide per dwelling per year). Design Emission This is the actual annual emission of carbon dioxide predicted to arise from the building design. GLA Technology Hierarchy In the London Plan Alterations (2008), the GLA provide a hierarchy of Clean technologies to consider in order of merit according to the normal benefit these technologies are deemed to contribute to reducing carbon emissions. The hierarchy is as follows: connection to existing CCHP/CHP distribution networks site-wide CCHP/CHP powered by renewable energy gas-fired CCHP/CHP or hydrogen fuel cells, both accompanied by renewables communal heating and cooling fuelled by renewable sources of energy gas fired communal heating and cooling. Merton Rule This is an approach to planning policy, seeking delivery of a percentage saving of carbon emissions (originally 10%) through the use of renewable energy technologies. It originated in the London Borough of Merton, but has now been adopted widely (see www.thermertonrule.org). Target Emission This is the stated maximum allowable emission rate within the Building Regulations for a particular type of building (detached house, semi, flat or other). The Code defines more exacting standards measured as a percentage reduction against this Target Emission. Thermal Bridging arises when materials that are poor insulators come in contact, allowing heat to flow through the path created. For example, structural steel beams will represent a good path of conduction of heat. Thermal breaks are required to prevent the heat being conducted away. Thermal Mass represents the capacity of a material to store and retain heat (or coolth). This is different to insulation, which simply prevents conduction of heat through itself but does not itself have the ability to store heat or coolth. A building with high thermal mass can help to average out the day/night fluctuations in outdoor temperature. U-Values relate to the level of insulation of a building and dictate the rate of heat loss through the buildings faade (walls and windows), roof and walls. The lower the U-value the better, indicating reduced heat loss.



APPENDIX C HOW MUCH DOES IT COST?

The cost estimates provided in this document are rules of thumb only, ball-park figures. They have not been obtained from any contractors or suppliers, but rather drawn from publicly available documents.

The intent of providing these cost figures is primarily to provide a sense of magnitude so that it is possible to determine whether costs quoted on individual projects are likely to be reasonable or not.

A key caveat should be further taken into consideration. The cost of installing renewable energy technologies usually involves three factors:

the renewable energy technology kit itself;

installation costs; and

building adaptation costs.

For example, the cost of a CHP system itself may be more than equivalent boilers, but is still the same order of magnitude. A key element of the cost of CHP lies in the requirement for centralised heating and cooling water pipework to be incorporated into the building design, together with appropriate heat exchangers within dwellings. The cost quoted by a developer for incorporating CHP into a development will depend what he would have otherwise intended to do. If he had aimed to install an all electric system, then the cost of up-grading to CHP will be many thousands of pounds per unit (well over 5,000 per unit, closer to 10,000). But if the developer had already intended to install a centralised boiler plant to provide heating only, then he would have already assumed the costs of the pipework. The key cost of up-grade would be the CHP unit in place of a boiler, which would be relatively nominal.

The same applies to the use of Solar Water Panels placed on blocks of flats. These would require a centralised hot water and/or heating system. In contrast, incorporating wind or PV into buildings can be much less problematic; but it still requires consideration as to how the energy is distributed fairly between dwellings in a multi-unit building.

Cost of installing renewable technology consequently depends very much upon the baseline assumptions in the developers cost model. When entering any negotiations on such matters, you should always ask what the baseline assumptions are, on to which the new costs are being added.



APPENDIX D WHAT GOES WITH WHAT?

Set out below are two quick reference tables to help remind you about the different technologies the energy the produce and whether they match.

Energy Type Renewable Electrical Thermal

BEWARE

Centralised Boiler

No Efficient, but not renewable

CHP No Excess heat conflicts with other systems

Photovoltaic Yes Still costly for level of output

Solar Water Yes Lifestyle implications

GSHP Yes Technology difficult to get right

ASHP Yes Technology still young and fickle

Biomass Neutral On-going cost, sourcing and maintenance

Biofuel No In buildings, no benefit against gas

Wind Yes Over-estimates in energy generated

Boile

r

CHP

PV

Sola

r W

ater

GSH

P

ASH

P

Biom

ass

Win

d

Boiler CHP PV Solar Water GSHP ASHP Biomass Wind

a planner's guide to carbon - 7-8-08

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