Hackbridge a Zero Carbon Suburb

Transcription

1 Hackbridge a Zero Carbon Suburb An area based strategy for zero carbon buildings 2 nd December 2011 A report from BioRegional Development Group Funded by: The JJ Charitable Trust The Mark Leonard Charitable Trust The Ashden Trust

2 Revision Description Date Issued by Reviewed by V0.1 1 st Draft 1 st Nov 2011 Joanna Marshall-Cook Julie Codet-Boisse V0.2 2 nd Draft 30 th Nov 2011 Joanna Marshall-Cook Sue Riddlestone V1 Final 2 nd Dec 2011 Joanna Marshall-Cook Julie Codet-Boisse Author: Joanna Marshall-Cook BioRegional Development Group BedZED Centre 24 Helios Road Wallington Surrey SM6 7BZ Tel : info@bioregional.com Website : 2

3 Formulating a zero carbon strategy for Hackbridge Contents 1 Executive Summary Building stock Energy efficiency and building integrated renewable energy District energy systems Measures considered to retrofit the buildings in Hackbridge Other potential sources of community energy generation Scenarios to achieve zero carbon Implementation strategy Introduction Hackbridge Zero carbon Hackbridge Aims of the study Methodology Existing energy studies undertaken in Hackbridge Approaches considered to retrofit the buildings in Hackbridge Full retrofit combined with renewable energy technologies District energy Light retrofit combined with district energy Residential buildings Residential building types Energy demand per building type Existing schemes to retrofit the residential building stock Full retrofit - Energy efficiency and renewable energy Full retrofit summary Light retrofit Non-residential buildings Non-residential building types Energy demand per building type Existing schemes to retrofit the non-residential building stock Full retrofit Energy efficiency and renewable energy Full retrofit summary Light retrofit New buildings in Hackbridge Energy demand and carbon emissions from new buildings Maximum energy efficiency level with renewable energy District energy Pipe-work for the district heating network Connection Energy generation

4 Formulating a zero carbon strategy for Hackbridge 9.4 Costs and carbon savings from district heating Investigating the economic viability of a district heating scheme Combining district heating with light retrofit measures Investigating the economic viability of a district heating scheme Comparison of the different approaches to retrofitting Community energy generation Wind turbines Hydropower Solar technologies Scenarios to achieve Zero Carbon Hackbridge Total energy demand for all buildings in Hackbridge Scenario Scenario Scenario Scenario Conclusions Comparison of the different scenarios to achieve zero carbon Implementation strategy options Community engagement Light retrofit measures financed through the Green Deal Connecting the district energy network to the existing buildings Establishing a smart grid in Hackbridge Next steps The zero carbon strategy tool Annex 1: Energy Service Companies (ESCos) explained Annex 2: Building types in Hackbridge Annex 3: Assumptions Annex 4: Energy demand benchmarks for non-residential buildings Annex 5: Total energy savings and CO2 emissions from energy efficiency measures per building type Annex 6: District heating assumptions Annex 7: Costs and CO2 savings for different building types when connected to a district heating network Annex 8: Carbon emission savings achieved by district heating Annex 9: Costs and CO2 savings for different building types when connected to an energy network with light retrofit Annex 10: List of meetings and events attended in relation to the Zero Carbon Hackbridge strategy Annex 11: Initial community engagement plan Stakeholder engagement

5 Section 1: Executive Summary 1 Executive Summary In 2009, the London Borough of Sutton, its partners and the community made Sutton the first One Planet Borough by launching a One Planet Action Plan and committing to live within a fair share of the earth s resources by A suburb of Sutton called Hackbridge that is the home of the UK s largest mixed us e sustainable community (BedZED) has been identified as Sutton s pilot area for the One Planet initiative. BioRegional are working in partnership with the London Borough of Sutton to make all buildings in Hackbridge zero carbon. This is a key part of the council and community activity to make Hackbridge a truly sustainable suburb and Sutton s commitment to become a One Planet Borough. The purpose of this study is to define a strategy to achieve this objective, identify costs and energy bill savings for the residents of Hackbridge and set out an implementation plan. The strategy looks at numerous ways to achieve zero carbon including behaviour change, energy efficiency, renewable energy technologies and district energy provision. The different buildings in Hackbridge were identified along with their current energy demand. Different options to retrofit these buildings were identified before looking at community scale renewable energy technologies. Scenarios were then established to achieve zero carbon. 1.1 Building stock The building stock in Hackbridge is a very varied combination of residential and non-domestic properties. More specifically, Hackbridge includes: 2,500 dwellings, the majority of which are of solid wall construction from the 19 th century and the 1930s. There is also a large number of timber framed flats built in the 1990 s that have electric heating. A variety of non-residential building types ranging from industrial buildings to high street shops and schools. Significant levels of regeneration are also occurring within Hackbridge. Detailed plans include 1,100 new homes, shops, and employment space, as well as community facilities. Based on the existing and proposed new buildings, the energy requirements of Hackbridge in 2020 are estimated to be 38,927MWh of heat and 23,652MWh of electricity. This was used as a baseline to then model the impact on energy requirements of different types of energy measures. Three types of intervention are possible: 1) Include measures within the building (energy efficiency, behaviour change and renewable energy); 2) Connect buildings to a district heating network; and 3) Integrate off-site community renewable energy technologies. 5

6 Section 1: Executive Summary 1.2 Energy efficiency and building integrated renewable energy Different levels of energy efficiency and renewable energy were modelled for both the existing and new build stock. These are: For the existing stock: Full retrofit whereby maximum measures that could be installed independently of the cost efficiency of the measures in relation to the carbon saved Light retrofit whereby only those measures that paid for themselves through energy bill savings over a 25 year period or less were chosen. These measures should also be able to attract Green Deal finance For the new build stock: Modelling to very high standards of energy efficiency, close to the Passivhaus standard 1, along with the integration of renewable energy technologies. Construction to the energy efficiency levels required by the current Building Regulations. 1.3 District energy systems A review of the potential for local energy generation and supply was undertaken, taking into consideration the resources available locally which could be used for energy generation and identifying any constraints or opportunities relating to this. There is the potential for energy generation and distribution through a heat network in Hackbridge powered by the following existing and planned sources of energy: 1. A landfill site locally is generating electricity and heat from the combustion of methane. The owners of the largest development site in Hackbridge are currently procuring a heat network to supply the site which may use this waste heat. 2. An existing pyrolysis plant. This plant heats waste in the absence of oxygen. A gas is produced which can then be burned in an engine to generate electricity. Heat is a by-product for which there is currently no demand. 3. An energy from waste facility may be built next to the landfill site to process all the household waste from the London Boroughs of Sutton, Kingston, Croydon and Merton that is expected to remain after recycling has taken place. This facility would produce electricity primarily and heat would be produced as a by-product. 1 A Passivhaus building is one in which thermal comfort can be achieved without the need of heating sources such as a boiler. 6

7 Section 1: Executive Summary 4. An anaerobic digestion plant could also be built near the landfill site. This plant would produce biogas from food and garden waste. The biogas could be burned in a generator to produce electricity and heat. 5. An existing advanced composting facility that generates heat to the north of Hackbridge 2. Therefore along with the installation of energy efficiency measures, the connection of all the existing buildings to a district energy network powered by some of the energy sources listed above was considered. In addition, the use of a biomass combined heat and power (CHP) energy network was also modelled. The biomass CHP generator would produce electricity with heat as a bi-product. It would be fuelled by wood-chip from arboricultural arisings and coppicing. This option was investigated because the other options all rely on the collection of large quantities of waste which, based on the current recycling targets in the UK, should reduce in the future. Wood-chip in contrast is a renewable source of fuel and, with increased levels of woodland management, around 8% of the UK s heat demand could be met through woodfuel Measures considered to retrofit the buildings in Hackbridge In summary for each of the building types, these three different measures to retrofitting the buildings were modelled: 1. Full retrofit combined with building integrated renewable energy technologies and behaviour change 2. Light retrofit those simple, low cost retrofit measures that could be paid for by the Green Deal and behaviour change. 3. A district heating network connecting all of the buildings in Hackbridge to low/zero carbon energy sources. 4. Light retrofit measures and behaviour change combined with connection to a district energy network. The cost efficiency of these different approaches is shown in Table See for more information 3 Forestry Commission (2007) English woodfuel strategy 7

8 Section 1: Executive Summary /tonne CO2e saved Existing Flats Existing houses Existing nonresidential New-build homes New-build nonresidential Full retrofit Light retrofit District heating (waste heat and biogas CHP) Light retrofit and district heating (biogas CHP with biogas back-up) Table 1-1: Comparison of cost vs. carbon savings for different measures to meet zero carbon The full retrofit approach is most expensive for flats (none of the flats in Hackbridge have solid walls, for flats with solid walls this would be even more expensive, as it is expensive to install solid wall insulation). This higher cost is because flats have a lower surface area to volume ratio and therefore have less heat loss than houses, meaning that they have lower heating bills to start with and therefore insulation has a smaller impact on their carbon emissions. Another result from this comparison is that constructing to higher levels of energy efficiency (e.g. to achieve Code for Sustainable Homes Levels 5 or 6) is a significantly less cost effective way to save carbon than retrofitting existing buildings. Just retrofitting the buildings and installing building integrated renewable energy does not achieve zero carbon on its own. The only way to meet zero carbon is the combination of light retrofit and a district energy system. District heating on its own doesn t achieve zero carbon as the electrical demand from the buildings is too high compared to the heat demand. As district energy systems need to be designed to meet the heat demand of the buildings and the ratio of heat to electricity produced in combined heat and power systems is around 1:1 there is therefore not enough electricity produced from the district energy to achieve zero carbon. The cost of only retrofitting the district heating system to houses would pay itself back through the sales of heat with a heat price of 3.5p/kWh, which is similar to the current price of gas. However, for the flats (which have a lower heat demand and therefore less revenue is made from the heat sales) an additional 2,833 would 8

9 Section 1: Executive Summary be needed to meet the cost of connecting the flats to the network. Combining retrofitting with the district heating reduces the revenue from heat sales for the district heating scheme, therefore additional capital is required for both houses and flats. In terms of energy bill savings for residents, the full retrofit option provides the highest savings. However, it also has the highest cost, resulting in a simple payback of around 43 years for residential buildings, but only around 15 years for non-residential buildings. The district heating option on its own is unlikely to significantly reduce energy bills for residents; this is because the cost of the infrastructure would need to be paid from profits of the heat sales. If some of the cost of the infrastructure was paid for by the developer of the proposed waste management facility or through public money it may be possible to provide lower energy tariffs to residents. 1.5 Other potential sources of community energy generation (not integrated into buildings) Due to the built up nature of Hackbridge, the options for installing large scale renewable energy systems such as wind turbines were limited. However, it was identified that two 1MW wind turbines could be installed on Beddington Farmlands in Hackbridge. Beddington farmlands is currently a sewage works and landfill site. They would generate in the region of 1,700,000kWh per year (assuming a hub height of 45m) and would together cost around 2.4 million. The cost per kwh of energy generated would be 0.7. There is however a significant barrier to installing wind turbines on Beddington Farmlands, in that it is a major site for birds. This technology has been considered in the building of some scenarios to achieve zero carbon Hackbridge. However, a full environmental impact assessment would be required to confirm feasibility. A hydro-power scheme on the River Wandle (which runs through Hackbridge) was investigated. However, the conclusion was that there was insufficient power in the water to make this feasible. 1.6 Scenarios to achieve zero carbon Combining the approaches to retrofit the individual buildings with the community energy generation options (such as the wind turbines) resulted in the following four scenarios that could achieve or nearly achieve zero carbon Hackbridge. Scenario 1: Full retrofit for all buildings, behaviour change measures, building integrated renewable energy technologies (solar thermal and solar photovotaics) and large scale wind turbines on Beddington Farmlands. Scenario 2: District energy, building integrated solar photovoltaic panels and large scale wind turbines on Beddington Farmlands. Scenario 3: Behaviour change measures, light retrofit measures, building integrated solar photovoltaic panels and district energy. 9

10 Section 1: Executive Summary Scenario 4: Light retrofit with solar photovoltaic panels and district energy for existing flats, full retrofit with building integrated renewable energy technologies (solar thermal and solar photovoltaics) for existing homes and non-residential buildings, constructing to current building regulations for new buildings and connecting them to a district heating network. In addition, wind turbines would be installed on Beddington Farmlands. Table 1-2provides a comparison of these different scenarios to achieve zero carbon Hackbridge, showing the costs, percentage reduction in carbon emissions, the value for money and the remaining carbon emissions. Cost ( ) % reduction in /kg CO2e Remaining Advantages Disadvantages CO2e emissions saved CO2e emissions (kgco2e/yr) Scenario million 61% 6 12,407,558 Increases thermal comfort, High cost, lowest CO2e savings reduces fuel poverty, minimises natural resource use. Scenario million 66%-88% 3 3,775,166 Low cost, relatively easy to install Doesn't increase thermal comfort, high fuel bills, low CO2e savings Scenario million 59% -100% 3 0 Achieves zero carbon, increases High cost thermal comfort, reduces fuel poverty, minimises natural resource use. Scenario million 75%-79% 6 6,505,447 Highest cost, low CO2e savings Table 1-2: Comparison of the different scenarios to achieve zero carbon Hackbridge For scenarios 2 to 4 which involve district energy the precise costs and carbon savings depend on the energy source supplying the energy network. They are here presented within a range. The energy from waste results in some of the lowest carbon savings, the biogas CHP has some of the highest carbon savings (and combined with light retrofit measures achieves zero carbon). Scenario 3 seems to be the optimal choice, as although it is not the cheapest option it has many other advantages including: Provides a zero carbon solution without the use of wind turbines (wind turbines may not be feasible because of the birds on Beddington Farmlands). 10

11 Section 1: Executive Summary Will result in reasonable fuel bill savings for the residents of Hackbridge (although if the retrofit was financed through the Green Deal these savings would initially just be used to repay the Green Deal finance). Will increase the thermal comfort of the buildings in Hackbridge. Allows more homes to be heated by the energy plant that we have available. Will not require every resident in Hackbridge to undertake very expensive retrofit measures that do not pay for themselves. Will use heat sources from Hackbridge that are currently being wasted. Although this is the optimal environmental solution it should be borne in mind that by reducing the energy demand of the buildings through energy efficiency measures, the amount of potential heat sales revenue for the organisation installing and operating the energy network (the ESCo) diminishes, this in turn reduces the amount of money that can be spent by the ESCo on the infrastructure. In order for this option to be viable while selling the heat for slightly less than the current price of gas and buying the heat for around 1p/kWh, an additional 3,124 for the houses and 6,813 for the flats would be needed to pay for connection to the network. The cost in flats is higher because for many flats in Hackbridge a new wet central heating system is needed to replace the current electric heating system, whereas houses in Hackbridge already have central heating and radiators. The energy source for the network will depend on the heat sources that become available over time. Currently there is waste heat from the landfill gas site and the pyrolysis plant (this would produce enough heat for about half of Hackbridge). This could be supplemented by additional waste heat from the proposed waste management facility, or if the anaerobic digestion facility goes ahead the biogas CHP using the gas from the anaerobic digester would be possible (either of these two options would supply enough heat and electricity for the whole of Hackbridge). The waste management facility or the anaerobic digester are likely to be built by Therefore although zero carbon would not achieved as soon as the energy network is established there will be the potential to achieve zero carbon in the future. These scenarios rely on generating all our energy within Hackbridge. However, there are other options that would be acceptable under the zero carbon definition. For example purchasing electricity under a power purchase agreement. A power purchase agreement would involve the community agreeing to buy electricity from a certain supplier, which allows them to install additional renewable energy capacity elsewhere. 1.7 Implementation strategy Whilst preparing the scenarios for achieving zero carbon Hackbridge, BioRegional have also been meeting with a number of key stakeholders to identify what steps would need to be taken to make Zero Carbon Hackbridge a reality. Our findings from these meetings and additional research are that in order to realise scenario 3, the following would be required: 11

12 Section 1: Executive Summary Community engagement with both residential and non-residential occupiers in Hackbridge. This will make them aware about the zero carbon Hackbridge project and how it benefits them, how they can change their behaviour to save energy and how they could go about financing and installing retrofit measures. Stakeholder engagement with the Local Authority, Sutton Housing Partnership (the owner of nearly all of the social housing in Hackbridge) and the owners of the private blocks of flats in Hackbridge. Offer a light retrofit package to residents in Hackbridge either through promoting existing Green Deal providers or by the Local Authority becoming a Green Deal provider or by setting up a community ESCo. Organise for every building in Hackbridge to be fitted with solar photovoltaic panels using a bulk purchase scheme. Co-ordinate with the developers of the energy network for the Felnex Trading Estate to extend the network to the existing buildings in Hackbridge and to develop a community stake in any ESCo that is set up. Disseminate the zero carbon strategy tool that BioRegional have developed to allow other areas to produce their own zero carbon strategy. Hackbridge presents a unique opportunity to create an example of what a sustainable suburb could look like. BioRegional and the London Borough of Sutton will be taking this vision forward; creating innovative solutions to deliver behaviour change, energy efficiency, building integrated renewable energy and district energy from waste sources. Key to our success will be making a project that the whole community can lead on. This project will be the first of its kind, retrofitting at scale to deliver truly zero carbon buildings (not just loft and cavity wall insulation). 12

13 Section 2: Introduction 2 Introduction 2.1 Hackbridge In 2009, the London Borough of Sutton, its partners and the community made Sutton the first One Planet Borough by launching a One Planet Action Plan and committing to live within a fair share of the earth s resources by Some of the most challenging environmental targets in the UK were set, and good progress is being made. One Planet Living 4 is a framework developed by BioRegional (a social enterprise and environmental charity located in Hackbridge) it incorporates ten principles of sustainability encompassing individuals, the community, businesses and the public sector. Hackbridge has been identified as Sutton s flagship sustainable community. This is because Hackbridge displays some major strengths, but at the same time is an ordinary suburb. The development proposed in the area also offers an opportunity to try out certain initiatives. Hackbridge contains the world renowned BedZED (Beddington Zero [Fossil Fuel] Energy Development) where BioRegional are based. Significant levels of regeneration are occurring within Hackbridge. A masterplan has been developed to create the UK's first truly sustainable suburb'. Detailed plans include 1,100 new sustainable homes, more shops, leisure and community facilities, new jobs, sustainable transport including pedestrian/ cycle initiatives and improved networks and open spaces. The Council s Core Strategy for planning was adopted in December The strategy contains a commitment for all new buildings constructed in Hackbridge from 2011 onwards to be zero carbon. The Hackbridge community are currently working on their Neighbourhood Plan as part of CLG s Neighbourhood Planning Front Runners Scheme. 2.2 Zero carbon Hackbridge The UK is striving to achieve 34% greenhouse gas emissions reductions by 2020 and 80% by The UK s domestic buildings contribute 23% to the UK s greenhouse gas emissions. Whilst new homes are being built to much higher environmental standards (Code for Sustainable Homes level 4 thermal standards become statutory in 2013), most of the UK s existing building stock is very energy inefficient. Working together with BioRegional, the London Borough of Sutton has committed to a 100% reduction in carbon dioxide emissions from buildings by 2025, with additional ambitious carbon targets for construction materials, transport, food and consumer goods. Hackbridge is the best place to pilot this zero carbon buildings target. In fact, the following initiatives are already taking place in the area: Climate Change Act

14 Section 2: Introduction Sustainability visits: Eco-auditors visited around 70 homes in Hackbridge in 2008 to advise them about sustainable living, in particular focussing on energy efficiency. Hackbridge Low Carbon Zone: Part of Hackbridge is the location for one of the Greater London Authority s Low Carbon Zones. Residents are being provided with free energy audits, easy energy efficiency measures and are eligible for discounted insulation measures. Greening businesses in Hackbridge: The London Borough of Sutton secured ERDF funding to deliver a programme of sustainability support for the businesses in and around Hackbridge. BioRegional are delivering this work. Businesses are given one to one support on reducing energy, water and waste. So far 39 businesses in and around Hackbridge have had an energy audit undertaken. Organisation-specific environmental policies have been formulated for 18 of these businesses. A district heating network has been proposed and encouraged by the Local Authority and is being procured by the developer of the largest development site in Hackbridge. This may be supplied by waste heat from a nearby landfill site. There are also a number of waste heat sources present in the area that could be harnessed for heating buildings in Hackbridge, by extending the proposed energy network. The River Wandle that runs through Hackbridge would provide an ideal route to lay district heating infrastructure along at a low cost. 2.3 Aims of the study This study has two aims, firstly to help define a strategy to retrofit Hackbridge by identifying: How many and what type of buildings would need to be retrofitted. What different approaches could be taken to retrofitting, e.g. energy efficiency, building integrated renewable energy technologies or district heating. What would be the cost and delivery plan for the preferred approach, which may encompass a range of technologies. The second aim is to develop an approach for formulating a zero carbon strategy for an area that other organisations, such as Local Authorities, could adopt. The structure of the report is as follows: 1. Methodology 2. Existing energy studies undertaken in Hackbridge 3. Approaches considered to retrofit the buildings in Hackbridge 14

15 Section 2: Introduction 4. Retrofitting residential buildings 5. Retrofitting non-residential buildings 6. Energy options for new buildings 7. District energy 8. Community energy generation 9. Scenarios to achieve zero carbon Hackbridge 10. Conclusions 11. Implementation strategy 15

16 Section 3: Methodology 3 Methodology The following methodology was used to establish a strategy to make Hackbridge a zero carbon suburb: Establishing the baseline 1. A gap analysis was completed looking at the energy studies that have been undertaken in Hackbridge to understand what further research is required in order to establish a zero carbon strategy for the suburb. 2. The different existing building types in Hackbridge (looking at construction type, age, tenure and detachment) were identified along with the number of each type. 3. An estimate of the number and type of new buildings expected to be developed in Hackbridge was made using data from the draft Hackbridge Masterplan Energy demand for the different building types (new and existing) was established using data from a previous Parity Project s study 7 for the existing residential buildings, benchmark data for the non-residential buildings and Building Regulations data for the new buildings. 5. Greenhouse gas emissions associated with the energy demands of each of the buildings were calculated using the 2011 DEFRA greenhouse gas conversion factors 8. All greenhouse gases covering Scopes 1 to 3 were included. Scope 3 emissions include emissions from the extraction and transportation of the fuel. For ease of reading throughout the report all greenhouse gas emissions are termed carbon emissions or CO2e in shorthand. Individual building approach 6. The energy efficiency measures and renewable energy technologies that are appropriate to each building type based on construction type and available space for renewable energy technologies were identified. 7. Cost, energy savings and carbon emission savings for the different energy efficiency measures were identified. 8. The diminishing energy savings from installing one measure in conjunction with a number of other energy efficiency measures were accounted for in order to identify the total energy savings and reduction in carbon emissions possible from retrofitting. 6 Hackbridge Sustainable Suburb Final Draft Masterplan. [online] Available from: 7 Parity Projects. (2008) Energy Options Appraisal for Domestic Buildings in Hackbridge. 8 August 2011 Guidelines to DEFRA/DECC s Greenhouse Gas Conversion Factors for Company Reporting. [online] Available from: 16

17 Section 3: Methodology 9. The costs and carbon reductions possible from retrofitting the buildings with a minimal amount of energy efficiency measures in line with those measures that would be able to attract Green Deal finance was modelled. This is termed the light retrofitting approach. 10. For the new buildings planned in Hackbridge a higher level of energy efficiency than is required by the proposed 2016 Building Regulations was modelled along with solar photovoltaic panels and solar thermal collectors. Hackbridge wide approach 11. The potential large scale sources of heat and electricity in the vicinity of Hackbridge were investigated to identify how much heat and power is available. 12. The installation of district energy networks to transport the heat and power already available in Hackbridge was considered when: o o No retrofitting had taken place A light retrofit had taken place 13. The remaining energy demand that would still need to be met once all the energy efficiency measures and building integrated renewable energy technologies have been installed was identified. 14. The potential for community owned renewable energy generation sources were investigated to identify where they could be situated, how much they would cost and how much energy they could produce. Developing zero carbon scenarios 15. Different scenarios were identified that would enable Hackbridge to become zero carbon. 16. The total costs, energy and carbon savings from implementing each of these scenarios was modelled. The number of homes that were likely to already have some of the energy efficiency measures installed (this was estimated using the English Housing Survey) was taken into consideration when identifying the total costs. 17. An implementation plan to achieve zero carbon Hackbridge was developed. 17

18 Section5: Approaches considered to retrofit the buildings in Hackbridge 4 Existing energy studies undertaken in Hackbridge In 2008 Parity Projects was commissioned by BioRegional to complete an Energy Options Appraisal for Domestic Buildings in Hackbridge7 which provided an estimate of the number of homes that would need to be retrofitted in Hackbridge, what the cost would be and what energy and carbon savings would be possible. In addition, CEN were commissioned by the London Borough of Sutton to produce an Evidence Base for a Zero Carbon Policy in Hackbridge 9. This study focussed on the new buildings that were being developed in Hackbridge and how much it would cost to make them zero carbon. This study was used as an evidence base to support the Council s Core Strategy which requires all new buildings in Hackbridge to be built to a zero carbon standard. Despite the availability of these two studies, the following further work was required to develop a comprehensive strategy for Hackbridge to become a zero carbon suburb: The existing non-residential buildings within Hackbridge had not been considered in either of the two studies. Therefore it was still necessary to ascertain the best approach to make these buildings zero carbon. Since 2008, the costs, energy and carbon savings of retrofitting have become more certain, an update was therefore required. No unifying strategy has been prepared which identifies how the new-build programme and the retrofitting of the residential and non-residential buildings in Hackbridge meshes together. In particular identifying the amount of energy that would still need to be met through decentralised energy sources in Hackbridge once retrofitting has taken place. A number of new financing mechanisms have become available since these studies were commissioned including the Feed-in Tariff, and the upcoming Renewable Heat Incentive, Green Deal and Energy Company Obligation. An implementation plan based on the data as to what is required to make Zero Carbon Hackbridge a reality was also needed. This study therefore seeks to address the outstanding questions outlined above. 9 CEN (2009) Hackbridge Sustainable Suburb: Evidence Base for a Zero Carbon Policy 18

19 Section5: Approaches considered to retrofit the buildings in Hackbridge 5 Approaches considered to retrofit the buildings in Hackbridge BioRegional firstly assessed what could be retrofitted to the individual buildings in Hackbridge. Initially only energy efficiency measures and renewable energy measures were considered. However, due to the presence of a number of existing heat sources within Hackbridge, the use of a district heating network harnessing these heat sources was also modelled. In summary, the following three different approaches to retrofitting the individual buildings in Hackbridge were explored: 1. Full retrofit combined with building integrated renewable energy technologies and behaviour change. 2. A district energy network connecting all of the buildings in Hackbridge to a low/zero carbon energy source. 3. Simple, low cost retrofit measures and behaviour change measures combined with connection to a district energy network. Once the individual approaches to retrofitting the buildings had been considered community renewable energy sources were investigated to meet any remaining energy demand. 5.1 Full retrofit combined with building integrated renewable energy technologies The installation of all the energy efficiency measures that are currently available on the market was modelled for each of the building types. Different energy efficiency measures are appropriate for the different building types, depending on their construction type, e.g. whether a cavity wall was present, and their detachment, e.g. a flat or a semi-detached house. There is a small cluster of listed buildings around Hackbridge Green, but other than for these buildings there should be no problem in obtaining planning consent for external solid wall insulation for the buildings in Hackbridge. Additionally, the installation of a solar thermal system to meet the summer hot water demand 10 was modelled as well as the maximum amount of solar photovoltaic panels that would fit on each building s roof. Hackbridge does not have any conservation areas within it therefore solar photovoltaic panels and solar thermal collectors can be installed using permitted development rights, without the need for planning permission. The rationale for not modelling the use of the following other renewable energy technologies that are suitable for building integration is provided below: Ground source heat pumps: The relatively high density nature of Hackbridge means that space would not be available for the ground loops that are required to collect heat for a ground source heat pump system. 10 Solar thermal systems must be designed to meet 100% of the summer hot water demand, which means that they meet around 60% of the total hot water demand for the year. If they were designed to meet 100% of the hot water demand throughout the year they would produce too much heat in the summer, which can lead to malfunctioning of the solar thermal system. 19

20 Section5: Approaches considered to retrofit the buildings in Hackbridge Air source heat pumps: The CO2 savings from air source heat pumps are minimal when compared to the use of gas heating 11 Wood-fuel heating: Individual wood-fuel units require significant user input for de-ashing and stocking wood which would not be appropriate for many users. In addition, there are significant transportation impacts from delivering woodfuel to nearly 3,000 different users in a small area. Wind turbines: in a built-up area such as Hackbridge the turbulence created by buildings leads to very poor performance of wind turbines in the grounds of buildings. The performance of building-mounted wind turbines is still unproven and they can lead to structural issues in the building. Finally, the reduction in energy demand from a number of simple changes in behaviour by the occupiers of the buildings has been modelled, such as lowering the temperature that the heating is set to. 5.2 District energy Due to the extensive re-development of Hackbridge, the London Borough of Sutton has long considered that a district energy network would be appropriate for the area. The developers of the largest of the development sites in Hackbridge, Felnex Trading Estate, are now investigating the potential for establishing a district heating network for their development in order to meet their zero carbon obligations. To the east of Hackbridge is a landfill site from where methane is collected and burnt in a gas engine to generate electricity. Heat is a by-product of this process but the heat is currently being wasted. One of the options being investigated by the developers of Felnex Trading Estate is building a heat pipe to deliver this heat to the new development on Felnex Trading Estate. It would then be possible to extend this network to the rest of the suburb. The London Borough of Sutton is keen to extend this network to cover not only the other development sites planned for Hackbridge, but also to existing buildings in the area too. In addition to the waste heat from the landfill site in Hackbridge there are a number of other sources of waste heat in the vicinity including: 1. A pyrolysis plant. This plant heats rubbish in the absence of oxygen. A gas is produced which can then be burned in an engine to generate electricity. Hot water is a by-product for which there is currently no demand. 2. A proposed energy from waste facility may be built next to the landfill site to process all the household waste from the London Borough s of Sutton, Kingston, Croydon and Merton. This facility would produce electricity primarily and heat would be produced as a by-product. 11 See: for further information on heat pumps. 20

21 Section5: Approaches considered to retrofit the buildings in Hackbridge 3. A proposed anaerobic digestion plant could also be built near the landfill site. This plant would produce biogas from food and garden waste. The biogas could be burned in a generator to produce electricity and hot water. 4. An advanced composting facility that generates heat to the north of Hackbridge 12. This study has therefore looked at the potential carbon savings and costs associated with connecting the existing buildings in Hackbridge to a district heating system. The different options investigated for generating the energy for the network were: 1. A biogas combined heat and power system, using biogas produced from the proposed anaerobic digester alongside waste heat from the landfill gas site, the pyroloysis plant and the advanced composting plant. There was not enough waste heat or enough biogas to look at these options separately. 2. A combined heat and power unit powered by an energy from waste process. 3. Biomass Combined Heat and Power (CHP) generation with the peaks in heat demand being met using a biogas boiler: The biomass CHP generator would be fuelled by wood-chip from arboricultural arisings and coppicing. The biogas would be generated from anaerobic digestion of food and garden waste. This option was investigated because the other options all rely on the collection of large quantities of household and commercial waste. However, based on the current recycling targets in the UK, such large quantities of waste may not be available in the future. Wood-chip in contrast is a renewable source of fuel and with increased levels of woodland management around 3.5million tonnes of woodfuel could be produced in England 13. The carbon savings from any additional generation of heat or electricity have counted towards the zero carbon target for Hackbridge. However, only heat from the network is provided to the buildings, the electricity is put back in the grid (but in doing so reduces the overall carbon emissions from grid electricity). It is possible to deliver the electricity to the buildings in Hackbridge, but this would require a private wire system, or some type of smart grid. Whatever the source of the energy for the network, it is likely to be run by an energy services company (ESCO), so that occupiers would pay for their heat and electricity in the same way as they would pay for their energy now. The ESCo would own and maintain the energy network, and possibly the energy generation equipment. They would also provide the metering and billing of the heat. More information on ESCos is provided in Annex See for more information 13 Forestry Commission (2007) English woodfuel strategy 21

22 Section5: Approaches considered to retrofit the buildings in Hackbridge 5.3 Light retrofit combined with district energy In order to heat and power more buildings with the energy sources available in the vicinity of Hackbridge, a number of low cost retrofit measures were considered to reduce the heating and electricity demands of the buildings before installing district heating. This would also help to reduce the energy bills for the residents of Hackbridge. The Government is establishing a framework, called the Green Deal, to enable private firms to offer consumers energy efficiency improvements to their homes, community spaces and businesses at no upfront cost, and to recoup payments through a charge in instalments on the energy bill. The key principle, or golden rule, for accessing Green Deal finance is that the charge attached to the bill should not exceed the expected savings, and the length of the payment period should not exceed the expected lifetime of the measures. In practice this means that the measures would need to payback in around 25 years. It is not yet known what level of interest would be charged on the loan. Therefore in order to estimate which measures would qualify for Green Deal finance, a simple payback (not including interest) has been used. It has been assumed that 25 years would be a standard loan period and many measures would be out of guarantee by this time. The low cost retrofit measures chosen are those that could attract Green Deal finance (based on a 25 year simple payback). These are termed light retrofit measures throughout the report. The same district energy generators were considered in this scenario as in the scenario where only district heating was installed, except that because the heat demand is lower once light retrofitting has taken place, the waste heat and biogas CHP options could be used separately. 22

23 Section 6: Residential buildings 6 Residential buildings 6.1 Residential building types The variety of building stock in Hackbridge makes it a very appropriate location for a zero carbon pilot. Hackbridge grew up in the late Victorian era; there are therefore a number of terraces from this period with solid walls (requiring costly solid wall insulation). These terraces also have poor ventilation (leading to damp problems) and ill-fitting single glazed sash windows. The more substantial developments of the 20 s and 30 s introduced new standards of design and workmanship and are in much better condition than the Victorian/Edwardian terraces. They also predominantly have solid walls but are usually less draughty than previous constructions and therefore have lower energy demands. Significant amounts of social housing were constructed in the 1950 s and this has been gradually retrofitted with loft and cavity wall insulation by the local authority to reduce heat loss. The majority of the housing stock that was built prior to 1980 is fitted with gas fired wet central heating systems (using radiators) with inefficient boilers. In the late 1980 s and the 1990 s two large estates of timber frame blocks of flats were constructed on brown field sites in Hackbridge. Most of these blocks of flats have electric storage heaters which are very costly to run and lead to high carbon emissions. These flats are all in the private sector and a high percentage of these are thought to be rented. The housing stock in Hackbridge has therefore been categorised into the following types, as shown in Table 6-1. Category Detachment Construction features Age Predominant tenure A End terrace and mid-terrace Solid brick Victorian Owner occupier/ private rental 23

24 Section 6: Residential buildings Category Detachment Construction features Age Predominant tenure B Small semi-detached Mid and end- terrace Solid brick 1930s Owner occupier/ Social housing C Mid-terrace or end-terrace Solid brick 1930s Owner occupier/ private rental D Large Semi-detached Solid brick 1930s Owner occupier/ private rental E Flats (all flats have 2 or 3 external walls) Cavity construction 1950s Social housing F Flats Timber frame 1990s Owner occupier/ private rental 24

25 Section 6: Residential buildings Category Detachment Construction features Age Predominant tenure G Small semi-detached houses Timber frame 1990s Owner occupier/ private rental H Flats Cavity construction 2001 onwards Owner occupier/ private rental I Small semi-detached or Mid or End terraced houses Cavity construction 2001 onwards Owner occupier/ private rental J BedZED: Flats and terraced houses Near Passivhaus construction 2002 Owner occupier/ private rental/ social housing Table 6-1: Predominant house and flat types within Hackbridge The number of each of these types of residential buildings is shown in Table 6-2. This shows that approximately a third of the residential buildings are flats (the majority of which are type F new build timber frame construction with electric storage heaters). The term maisonettes in this report means houses that have 25

26 Section 6: Residential buildings been converted into flats. The majority of maisonettes and houses were built between 1800 and 1939 and have solid walls. The BedZED homes are built to zero carbon standards and these have therefore been excluded from the study. Type Flats Maisonettes Mid-terrace house End-terrace/ semi-detached house A B C 69 D E 292 F 633 G H 41 I Total Table 6-2: Number of each residential building type in Hackbridge It was not possible to ascertain the breakdown in tenure between owner-occupier and private rented buildings for each of the different building types. However, using national and Sutton census data, it is possible to surmise that in Hackbridge 85% of non-social housing is owner occupied with the remaining 15% privately rented. Sutton Housing Partnership (The London Borough of Sutton s Social Housing Management Organisation) own 106 flats, the vast majority of which are building type E. They also own 46 houses which are type A and B. No other Registered Social Landlords have any significant stock in Hackbridge. In order to model energy demand and possible energy savings the buildings were further broken down into top floor flat, ground floor flat, middle floor flat and for houses whether there is a loft extension or a ground floor extension. Tables showing the numbers of each of these building types for each tenure can be found in Annex.2. 26

27 Section 6: Residential buildings 6.2 Energy demand per building type The energy demand for each building type was calculated using the previous study by Parity Projects 14. This study used actual energy bill data from a number of sampled households for each building type. The energy bill data was normalised against national energy data. The average energy demand and associated CO2 emissions for each building type can be seen in Table 6-3. Energy demand Flats Maisonettes Mid-terrace house End-terrace/ semi-detached house Average Heat demand (kwh/yr) 6,979 8,539 17,044 20,095 13,164 Electricity demand (kwh/yr) 7,904 4,610 5,785 6,777 6,269 Total energy demand (kwh/yr) 14,675 13,149 22,828 26,623 19,319 Total CO2 emissions (kgco2e/yr) 7,251 4,580 7,033 8,265 6,782 Table 6-3: Average energy demand and CO2e emissions per residential building type in Hackbridge Houses have over double the heat demand of the flats, this is due to their larger size and because they have a greater surface area to volume ratio which means they lose more heat. In contrast the electricity demand of the houses is only slightly higher than the flats. Electricity demand mostly relates to the occupancy of the building, which doesn t significantly differ between houses and flats. The relatively high CO2 emissions from the flats are due to the use of electric heating in the majority of them. Electric heating has over double the CO2 emissions compared to gas heating. 6.3 Existing schemes to retrofit the residential building stock in Hackbridge In order to establish how many of each building type still needed to be retrofitted, a survey of the different schemes to install energy efficiency measures in the area was undertaken. Hackbridge has been the location for the following pilot schemes to reduce energy demand from residential buildings. 2008: Eco-auditors visited around 70 homes in Hackbridge to advise them about sustainable living, in particular focussing on energy efficiency. Each resident was given a report to consolidate the advice. As a result of the visits: o 68% of households made a physical change to improve the energy efficiency of their home; and o 66% of householders made a behavioural change. 14 Parity Projects. (2008) Energy Options Appraisal for Domestic Buildings in Hackbridge. 27

28 Section 6: Residential buildings 2009-ongoing: Sutton Housing Partnership started a programme of work to install loft and cavity wall insulation using CERT 15 money. 2009: The London Borough of Sutton provided heavily discounted loft insulation (only materials, not labour) to everyone in Sutton. 29 households in Hackbridge took up this offer : The London Borough of Sutton, BioRegional and B&Q conducted one of the Pay as You Save trials in Sutton (2 of the properties were in Hackbridge). The Pay as You Save pilot trialled the Green Deal principle : Sutton obtained funding from the Greater London Authority to set up a Low Carbon Zone in Hackbridge 17. This consisted of free eco-audits for everyone, free loft insulation and cavity wall insulation as well as easy measures such as TRVs. Free measures including monitoring and solar photovoltaic panels were provided for the two local primary schools, the nursery and the community centre too. So far 296 households have taken up the offer of a free energy audit. Eight households had their boiler replaced 72 households had their loft insulated, 19 households had their home draught-proofed and 44 households had their boiler upgraded. BioRegional also obtained data from the Energy Saving Trust s database from the Home Energy Checks that they ask residents to fill in. However, the data from the Energy Saving Trust and all the initiatives listed above was quite insignificant when compared with the number of homes that have been insulated according to the English National Housing Survey. It has therefore been assumed that the level of energy efficiency installations is in line with the estimates from the English National Housing Survey as shown in Table 6-4. For the social housing stock in Hackbridge, which is predominately owned by Sutton Housing Partnership, the exact level of insulation that is installed is known and can be seen alongside the national statistics for owner occupier and privately rented housing. Insulation type Private rental Owner occupier Average (private rental and owner occupier) Sutton Housing Partnership Cavity wall 34% 50% 48 90% Over 200mm loft insulation 14% 25% 23 65% Full double glazing 64% 72% 71 19% Table 6-4: Estimates of level of insulation completed based on the English Housing Survey and stock data from Sutton Housing Partnership CERT- Carbon Emissions Reduction Target: Energy suppliers with a customer base in excess of 50,000 customers are required to make savings in the amount of CO2 emitted by householders. Suppliers meet this target by providing discounted energy efficiency measures to customers. 16 Further information can be found in the report detailing the findings from the PAYS trial: Pay-As-You-Save.pdf 17 More information can be found at: 18 Source: English Housing Survey ( ) 28

29 Section 6: Residential buildings The figures in Table 6-4 have been used to estimate the number of homes in Hackbridge that will still need loft and cavity wall insulation and double glazing to be completed. These total costs and carbon savings are detailed in Section Full retrofit - Energy efficiency and building integrated renewable energy technologies Appropriate energy efficiency measures were modelled for all of the residential building types shown in Table 6-2 taking into consideration the measures that would have already been installed due to Building Regulations requirements for the newer properties. To show some examples of the measures required, the cost of those measures and the energy and carbon savings that could be achieved for two example properties (a Victorian mid-terrace house and a 1950s top floor flat) are described in Sections and Example mid-terrace house Table 6-5 shows the result of this modelling for a Victorian mid-terrace house that has not been extended (building type A). The measures are ranked in accordance to the cost per kgco2e saved. The assumptions used to calculate the costs, energy savings and CO2 savings can be found in Annex 3. Energy efficiency measures to reduce heating and hot water demand Cost per home ( ) Energy savings (kwh/year) % CO2 savings Cost per kgco2 saved ( /kgco2) Payback (years) Lagging for hot water cylinder 25 1,383 4% Loft insulation (270mm) 200 2,306 6% Heating controls: 2 channel time clock, room thermostat and cylinder thermostat 295 2,306 6% Lagging for hot water pipe-work on external walls or floors % Draught-proofing: loft hatch, windows, air bricks and doors % Thermostatic radiator valves (cost if draining system for other work e.g. new boiler) % Boiler exchange (G to A rated) 2,705 4,842 12% Heat exchange ventilation % Double glazing 2,500 1,383 4% These figures are based on a number of different sources, including the Pay as You Save trial conducted in Sutton and the Energy Saving Trust. 29

30 Section 6: Residential buildings Cost per home ( ) Energy savings (kwh/year) % CO2 savings Cost per kgco2 saved ( /kgco2) Solid wall insulation (average cost of internal and external solution) 9,960 5,072 13% Draught-proofing floors (Silicone sealant to fill gaps beneath skirting board etc.) % Upgrade front and rear doors 1, % Under floor insulation for suspended timber or concrete floors 3, % Energy efficiency measures to reduce electricity demand Energy saving light bulbs % New A++ rated fridge/freezer % Building integrated renewable energy technologies Solar photovoltaic panels producing electricity (2.1kWp, 12m2 area) 10,500 1,756 14% Solar thermal system producing domestic hot water (4m2 panel, 350litre cylinder) 5,813 1,816 5% Total 40,741 24,391 76% - - Table 6-5: Costs, energy and CO2 savings from energy efficiency measures for a mid-terrace house (example is house type A) Payback (years) The two measures that provide the greatest CO2e savings are a new boiler and solid wall insulation. However, a new boiler costs only a fifth of that required for solid wall insulation. Significant CO2e savings can also be made through three simple measures (lagging for the hot water cylinder, loft insulation and heating controls). These three measures can be installed for only around 500. In contrast under-floor insulation and solid wall insulation have very high costs and in the case of under-floor insulation only save a limited amount of carbon. Based on the cost per kgco2e saved figures, it would only be worth installing double glazing once all the other retrofit measures except solid wall insulation, floor draught-proofing and under-floor insulation have been installed. Energy saving light-bulbs and replacing an old fridge/freezer with an A++ rated one offer very good value for money in terms of carbon savings. The payback period for the solar photovoltaic system includes the 786 per year revenue from the Feed-In Tariff. Similarly the payback period for the solar thermal system includes the 145 per year revenue from the proposed Renewable Heat Incentive. The total energy bill savings from all of these measures would be 1,192 per year. 30

31 Section 6: Residential buildings Example top-floor flat Table 6-6 shows the different energy efficiency and renewable energy measures that would be appropriate for a 1950s top floor flat that has cavity walls. Energy efficiency measures to reduce heating and hot water demand Cost per home ( ) Energy savings (kwh/year) % reduction in CO2 emissions Cost per kgco2 saved ( /kgco2) Payback (years) Lagging for hot water cylinder % Loft insulation 200 1,288 4% Heating controls: 2 channel time clock, room thermostat and cylinder 295 1,288 4% thermostat Lagging for hot water pipework on external walls/floors % Draught-proofing: windows, air bricks and doors % Cavity wall insulation % Thermostatic radiator valves (cost if draining system for other work e.g. new % boiler) Boiler exchange (G to A rated) 2,411 2,705 8% New front door to the whole building (split between flats) % Double glazing 2, % Draught-proofing floors (Silicone sealant to fill gaps beneath skirting board etc.) % Heat exchange ventilation % Energy efficiency measures to reduce electricity demand Energy saving light bulbs % New A++ rated fridge/freezer % Building integrated renewable energy technologies Solar photovoltaic panels producing electricity (2.6kWp 16m2) 13,000 2,174 18% Solar thermal system producing hot water (3m2 panel with 350litre cylinder) 5,813 1,816 5% Total 25,847 13,279 55% - - Table 6-6: Costs, energy and CO2 savings from energy efficiency and renewable energy measures for a standard top floor flat (example is flat type E) 31

32 Section 6: Residential buildings Significantly fewer measures are available for flats and as they are generally smaller and have a smaller surface area exposed to the elements so the carbon savings that can be achieved from energy efficiency measures are lower than for houses. This is demonstrated by the 74% reduction in CO2 emissions possible in a mid-terrace house compared to only 53% for a top floor flat. However, the initial carbon emissions from a flat are lower than for a house. The payback periods for the solar thermal system and the solar photovoltaic system include the revenues from the Feed-In Tariff and the planned Renewable Heat Incentive ( 973 and 145 per annum respectively). If all the measures listed above were installed the energy bill savings would be 798 per year Behaviour change Significant reductions in energy demand can be achieved by residents changing their behaviour. Table 6-7 shows the average percentage reduction in carbon emissions possible from different energy saving habits that residents could be encouraged to take up for each of the different residential building types. Greater carbon reductions would be possible than those listed below. However, it is probably unrealistic to assume that residents would go beyond these measures without significant increases in energy prices. No cost has been attributed to these behaviour change measures, although it is expected that in order to facilitate wide spread uptake of these measures, a behaviour change campaign would be required. Behaviour change measures Percentage reduction in CO2e emissions Flats Maisonettes Mid-terrace End-terrace/ semi-detached Behaviour change measures to reduce heating and hot water demand Turn down thermostat by 1 degree 1.0% 2.0% 3.1% 2.7% Turn thermostat down by 2 degrees 2.0% 4.0% 6.4% 5.0% Behaviour change measures to reduce electricity demand Washing machine only use at 30 degrees 0.9% 1.4% 0.4% 0.8% Eco-kettle 0.7% 0.6% 0.5% 0.5% Turn off lights when leaving a room 0.3% 0.8% 0.6% 0.2% Only boil as much water as you need in the kettle 0.4% 0.7% 0.8% 0.4% Turn appliances off and avoid standby 2.0% 4.5% 2.3% 1.4% Don't use the tumble drier 2.1% 4.1% 2.7% 1.8% Total 9.4% 18.1% 16.8% 12.9% Table 6-7: Percentage reduction in carbon emissions possible from different behaviour change measures 32

33 Section 6: Residential buildings Reducing the set temperature of the thermostat by 2 degrees (assuming the average temperature is 21 degrees or more) saves the most carbon for nearly all the home types. For the smaller homes stopping using the tumble drier has a big impact, this is because the energy required for the tumble drier is likely to be similar for all the home types, but the energy for heating the homes is much greater for the bigger homes. Turning appliances off had the next biggest impact. It should be noted that these figures are based on average user behaviour. Some residents will waste very large amounts of energy, and significantly higher carbon savings could be made than those listed here. Conversely some residents will already exhibit all of these behaviours and therefore fewer carbon savings can be made. 6.5 Full retrofit summary Table 6-8 shows the total reduction in carbon emissions possible from the full retrofit, the behaviour change measures and installing building integrated renewable energy measures that together make-up the full-retrofit option. The costs of each of these approaches are also shown. The total energy savings from installing all of the measures is not simply the sum of the energy savings of each individual measure. This is because when insulation is installed on its own the energy savings rely on the efficiency of the existing boiler (which is probably only around 70% efficient). However, if the boiler is upgraded to a 90% efficient one, less gas is required to heat the home and therefore less gas is lost through the roof. This means that the energy savings from insulating the loft will be less. A standard 14% factor 20 has been used to calculate the reduction in energy savings from each measure if they are all done together. Flats Maisonettes Mid-terrace house End-terrace/ semidetached house Average Behaviour change % reduction in CO2e 8% 15% 10% 9% 10% Energy efficiency % reduction in CO2e 15% 35% 40% 43% 33% Cost/ building ( ) 9,696 19,859 22,700 34,105 21,590 Building integrated renewable energy % reduction in CO2e 12% 13% 21% 19% 16% Cost/ building ( ) 11,483 6,424 18,920 19,311 14,034 Total Cost/ building ( ) 21,179 26,283 41,620 53,416 35,624 % reduction in CO2e 35% 63% 72% 71% 60% Energy bill savings ,018 1, Simple payback (years) Table 6-8: Total costs, carbon savings and energy bill savings from behaviour change, energy efficiency and building integrated renewable energy 20 Source: T-zero 33

34 Section 6: Residential buildings Table 6-8 shows that nearly as much carbon can be saved through very simple behaviour change measures than by installing the maximum amount of renewable energy technologies (solar thermal system and the maximum number of solar photovoltaic panels). All of the measures together would save between 520 and 1,182 a year in energy bills depending on the home type. The breakdown of this data into heat and electricity savings can be seen in Annex Light retrofit The next approach that was examined was the installation of all the measures that could attract green deal finance, plus a new A++ rated fridge/freezer, energy saving light bulbs and all the behaviour change measures (listed in Section 6.4.3). These measures are termed as light retrofit measures throughout the report. Based on the residential buildings in Hackbridge, all the following light retrofit measures would qualify for Green Deal finance. Loft insulation (providing there is no existing loft insulation). Draught-proofing Boiler exchange Thermostatic radiator valves New heating controls Lagging for the hot water cylinder Lagging for hot water pipe-work on external walls and floors Cavity wall insulation However, for flats that were built after 1990, draught-proofing, boiler upgrades, thermostatic radiator valves and cavity wall insulation have over a 25 year payback. Although A++ rated fridge/freezers and light bulbs have a very short payback period, they are moveable and therefore do not attract Green Deal finance. They have however been included in this modelling as many people will renew their fridge/freezers and light bulbs with energy efficient versions anyway. 34

35 Section 6: Residential buildings Flats Maisonettes Mid-terrace house End-terrace/ semidetached house Average existing houses Behaviour change % reduction in CO2e emissions for behaviour measures 8% 15% 10% 9% 10% Light retrofit Cost per building 1,711 1,810 4,208 4,366 3,024 % reduction in CO2e emissions for light retrofit measures 14% 24% 27% 27% 23% Total Energy bill savings per year Simple payback (years) Total % reduction in CO2e emissions 21% 38% 37% 36% 33% Table 6-9: Costs, CO2e savings and energy bill savings for residential buildings with light retrofit measures Table 6-9 shows that the cost of the energy efficiency measures ranges between 1,711 for a flat and 4,366 for an end-terrace house. They achieve between a 14 and 27% reduction in carbon emissions. This compares very favourably with the full-retrofit approach which although achieves nearly double the CO2 savings costs between 10 and 20 times more and has a payback period which is over four times greater. 35

36 Section 7: Non-residential buildings 7 Non-residential buildings 7.1 Non-residential building types Hackbridge has a variety of non-residential buildings ranging from high street shops to industrial buildings and warehouses. The exact profile of non-residential buildings alongside their typical construction (although there are many exceptions to the typical construction type) can be seen in Table 7-1. Number Average floor area (m2) Total floor area (m2) Standard construction and energy requirements Community centres and schools ,964 Mixture of cavity and solid walls. Radiators. Industrial buildings ,073 Corrugated roof with skylights. Gas convection heating. Industrial process loads. Public houses Victorian solid wall buildings. Single glazed windows. Radiators. Small high street shops (non-food) ,357 Victorian solid wall, large single glazed shop windows. Flat above. Offices 14 1,119 15,668 20th century, naturally ventilated and mostly cellular. Single glazed, radiators. Warehouses 5 1,313 6,567 Corrugated roof with skylights. Gas convection heating. Small food shops Victorian solid wall, large single glazed shop windows. Flat above. Refrigeration. Total/ average ,190 Table 7-1: Profile of non-residential buildings in Hackbridge 36

37 Section 7: Non-residential buildings It has not been possible to identify the tenure of each of these different building types; the Local Authority does not collect this data and thought that this data would not be collated anywhere. However, it is known that the schools are all owned by the London Borough of Sutton. It is likely that the other non-residential buildings are privately rented. 7.2 Energy demand per building type The energy demand for each building type was established using Chartered Institute of Building Engineer s benchmarks for energy demand per m 2 of floor area. Annex 4 lists the benchmark energy consumption used for each building type. The average energy demand and associated CO2 emissions for each building type can be seen in Table 7-2. Schools/ community Industrial Pubs High street shops Offices Warehouses Food shops Average Heat demand (kwh/yr) 116,678 79, ,813 24, , ,968 8, ,470 Electricity demand (kwh/yr) 44, , ,507 22,700 63,995 87,999 40, ,184 Total energy demand (kwh/yr) 140, , ,319 49, , ,967 48, ,137 Total CO2e emissions (kgco2e/yr) 51, ,535 97,959 20,574 54,045 99,410 26, ,613 Table 7-2: Average energy consumption and CO2 emissions for the different non-residential building types present in Hackbridge Due to the size of the industrial buildings and the significant amount of energy required for industrial processes, the majority of carbon emissions for nonresidential buildings come from industrial buildings. 7.3 Existing schemes to retrofit the non-residential building stock in Hackbridge The London Borough of Sutton secured ERDF funding to deliver a programme of sustainability support for the businesses in and around Hackbridge. This programme, delivered by BioRegional is called Greening Businesses in Hackbridge 21 Businesses are given one to one support on reducing energy, water and waste. So far 39 businesses in and around Hackbridge have had an energy audit undertaken. Organisation-specific environmental policies have been formulated 21 More information about the Greening Businesses in Hackbridge project can be found at: 37

38 Section 7: Non-residential buildings for 18 of these businesses. No energy saving measures have yet been installed, but a number of the businesses are investigating measures and there is a target to reduce carbon emissions from businesses by 700 tonnes by the end of the project. All of the community centres and schools in Hackbridge have had a full energy efficiency audit undertaken as part of the Hackbridge Low Carbon Zone programme. The results of these audits have been integrated into the study; therefore some measures which would not be appropriate for all non-residential buildings of that type have been suggested. 7.4 Full retrofit Energy efficiency and building integrated renewable energy technologies The costs, energy savings and CO2 savings were calculated for retrofitting all of the different non-residential buildings in Hackbridge. An example building from three different building types are shown here (a community centre, a small high-street shop and an office). All energy efficiency measures that were appropriate for each building type were modelled. In addition, the potential for installing solar photovoltaic panels and solar thermal collectors was assessed. Solar thermal collectors are not appropriate for schools because the collectors overheat during the summer holidays. For offices, industrial buildings, warehouses and shops, there is insufficient hot water demand to make it worthwhile installing solar thermal collectors, the space on the roofs would be better used for solar photovoltaic panels Community centre The community centre was built in the 1930s. A new wing was built in the 1990s and the boiler was upgraded 12 years ago. It has cavity walls. The centre is used seven days a week throughout the year and is 511m 2. Table 7-3 shows the different measures that would be appropriate for the building (based on the energy audit carried out for the Low Carbon Zone project). Costs, energy savings, the percentage reduction in carbon emissions, the carbon value per pound spent and the payback period are shown alongside. 38

39 Section 7: Non-residential buildings Cost ( ) Energy savings (kwh/yr) % reduction CO2e per kgco2e saved Payback period (years) Energy efficiency measures to reduce heating and hot water demand Boiler thermostat 130 4,532 5% Insulate pipes 90 1,994 2% Power flush radiators 550 9,970 10% Thermostatic radiator valves 210 1,234 1% Boiler exchange 2,293 12,955 13% Start-stop optimisation controls 500 2,492 3% Cavity wall insulation 1,281 5,507 6% De-stratification fans 924 3,753 4% Draught-proofing around windows and doors % Building management system 2,779 6,971 7% Reflective radiator panels % Double glazing 2,000 3,702 4% Flow temperature optimisation controls % Flat roof insulation 6,960 2,782 3% Energy efficiency measures to reduce electricity demand E cubes for fridges % Power-down switches % T12 to T5 light fittings 5,880 5,829 18% Dimming controls 1, % Building integrated renewable energy systems Solar photovoltaic panels (6kWp, 36m2) 47,250 7,900 24% Solar hot water with scaffold (5.5m2) 6,976 2,483 3% Table 7-3: Costs, energy savings and percentage CO2e reduction from energy efficiency and renewable energy measures for a community centre The most significant savings can be made from upgrading the boiler, installing a Building Management System and replacing the current inefficient T12 light fittings with the thinner more efficient T5 fittings that allow significantly more energy efficient light-bulbs to be used. For this particular community centre 39

40 Section 7: Non-residential buildings power-flushing the radiators (to remove sludge deposits which reduce the efficiency of the heat distribution) would also achieve very high CO2 savings. All of these measures would cost less than 2/kgCO2e saved. Insulating the roof is very expensive, because there is no loft space and therefore either insulation would need to applied externally and a new roof covering put on, or it would need to be installed internally which has many consequential costs. The payback period for the solar photovoltaic system includes the 3,041 revenue from the Feed-In Tariff. The payback period for the solar thermal system includes the 211 revenue from the anticipated Renewable Heat Incentive scheme. If all the measures listed above were installed the energy bill savings would be 3,840 per year Small high street shop Table 7-4 shows the results for the small high street shop that was modelled. This is a newsagent that is open seven days a week throughout the year and is 53m 2. It has solid walls. There is a flat above the shop and therefore there is no potential for loft insulation or for installing any solar technologies because the shop does not own the roof. Energy efficiency measures to reduce heating and hot water demand Heating controls: 2 channel time clock, room thermostat and cylinder thermostat Cost ( ) Energy savings (kwh/yr) % reduction in CO2e emissions /kgco2e saved Payback period (years) 400 2, % Door draught-proofing % Heat Exchange ventilation 350 1, % Install TRVs (cost if draining system for other work e.g. new boiler) % Boiler exchange 2,411 5, % Lag hot water pipework on external walls/floors % External solid wall insulation 4,511 5, % Double Glazing 1,800 1, % Draught-proofing floors (Silicone sealant to fill gaps beneath skirting board etc.) % Under-floor insulation for concrete floors 2, % Energy efficiency measures to reduce electricity demand Improved lighting (replace T12s with T5s) 39 1, % Table 7-4: Costs, energy savings and CO2 savings from energy efficiency and renewable energy measures for a small high street shop 40

41 Section 7: Non-residential buildings The installation of solid wall insulation saves the largest amount of carbon. However, it costs over 4 per kgco2e saved, this compares badly with upgrading the boiler ( 2 per kgco2e saved). Under-floor insulation provides the worst investment in terms of saving carbon, with a cost of 21 per kgco2e saved. If all the measures listed above were installed the energy bill savings would be 733 per year Large office complex Table 7-5 shows the results for the shop that was modelled. This is the largest office in Hackbridge, Sutton Business Centre (several different businesses rent out office space in the building), which has an internal area of around 4,000m2. It has cavity walls. It is occupied 5 days a week approximately between 8am and 6pm. Measures Cost ( ) Energy savings (kwh/year) % reduction in CO2e /kgco2e saved Payback period (years) Energy efficiency measures to reduce heating and hot water demand Lag hot water cylinder 50 37, % New boiler programmer , % Draught-proofing doors 100 6, % Heat exchange ventilation 1,750 44, % Boiler exchange 5, , % Cavity wall insulation 6,456 56, % 1 3 Lag hot water pipework on external walls/floors 1,764 10, % 1 5 Loft insulation 14,112 63, % 1 6 Draught-proofing floors 706 3, % 1 6 Thermostatic radiator valves 16,744 12, % 7 38 Double glazing 53,000 37, % 7 40 Under-floor insulation for concrete floors 56,448 12, % Energy efficiency measures to reduce electricity demand Improved lighting (replace T12s with T5s) 3,140 34, % 0 1 IT shut-off 5,000 22, % 0 2 Building integrated renewable energy systems Solar photovoltaic panels (41kWp, 246m2) 290,541 34, % Table 7-5: Costs, energy savings and CO2 savings from energy efficiency and renewable energy measures for a large office complex 41

42 Section 7: Non-residential buildings A solar thermal system is not appropriate for an office building, because the hot water demand is relatively low. Given that there is limited space availability on the roof, it is more appropriate to use the space for solar photovoltaic panels as the electricity demand of office buildings is high. The payback period for the solar photovoltaic system includes the 1,536 revenue from the Feed-In Tariff. As with the other buildings, under-floor insulation does not provide good value for money (payback period of 128 years). Due to the high heating demand, improvements to the efficiency of the heating system, such as upgrading the boiler, lagging the hot water cylinder and installing a new boiler programmer result in very high carbon savings relative to the capital investment. Making the lighting more efficient and installing an IT shut-off system (so that all IT equipment is turned off out of hours) also achieve high carbon savings per pound spent. If all the measures were undertaken the energy bill savings per year would be 12, Behaviour change Table 7-6 shows the average percentage reduction in carbon emissions possible from different behaviour change measures. Not all behaviour change measures are relevant to every building type (for example turning off the grill between service periods is only relevant to buildings with commercial kitchens such as pubs). 42

43 Section 7: Non-residential buildings % reduction in CO2 emissions from behavioural measures Schools/ community Industrial Pubs High street shops Table 7-6: Average percentage reduction in CO2e from different behaviour change measures for each of the different building types Offices Warehouses Food shops Average Turn thermostat down by 2 degrees 3% 0.3% 4% 5% 4% 10% 1.% 4% Change switch-on times for heating 1% 0.3% 4% 3% 4% 5% 0.6% 3% Close windows during heating/cooling period 1% 1% Ensure staff keep doors closed as much as possible 0.1% 2% 1.% Turn hot water temperature down by 1 degree C 0.3% 0.1% 0.4% 0.4% Turn off grills between service periods 19% 18% Turn computers off at night 9% 9% Turn off un-necessary equipment when not needed 19% 3% 3% 8% Turn off lights out of hours 13% 7% 4% 7% 0.6% 4% 6% Maintenance regime for refrigeration units (check for 1% 1% 9% 4% leaks and clear outdoor condensers) Maintain the industrial boiler for processes 5% 5% Utilise night cooling to minimise air conditioning load 2% 2% Prevent leaks from compressed air systems through 1% 1.% maintenance and leak detection Put computers on standby over lunch 1% 1% Discontinue use of electric heaters 1.% 1% Power downs 0.7% 0.7% Turn up refrigeration temperature by 1 degree 0.2% 0.9% 0.5% Turn off classroom projectors 0.3% 0.3% Turn monitors off at night 0.1% 0.3% 0.2% Set photocopiers/printers to be automatically on sleep 0.3% 0.2% mode after 5 minutes of not being out of work hours. Use high frequency inverters for fork lift truck charging 0.1% 0.1% 43

44 Section 7: Non-residential buildings Reducing the temperature that buildings are heated to leads to the greatest carbon savings (on average a 4% reduction), reducing the time that the building is heated for has a similar effect. There are some specific measures for certain buildings that lead to very high CO2 savings such as turning off industrial equipment (19% carbon savings). 7.5 Full retrofit summary Table 7-7 shows the costs and percentage reduction in carbon emissions from behaviour change, energy efficiency and building integrated renewable energy technologies that together make-up the full-retrofit approach. Behaviour change Energy efficiency Building integrated renewable energy Total % reduction in CO2e % reduction in CO2e Schools/ community Industrial Pubs High street shops Offices Warehouses Food shops Average 30% 31% 16% 19% 18% 13% 17% 21% 37% 4% 28% 15% 40% 50% 18% 28% Cost/ building ( ) 61, ,904 43,002 25,934 59, ,400 30, ,528 % reduction in CO2e 8% 8% 88% 0% 21% 4% 8% 20% Cost/ building ( ) 49,210 83, , , ,724 6,254 84,823 % reduction in CO2e 76% 43% 132% 34% 79% 68% 44% 68% Cost/ building ( ) 111, , ,864 25, , ,124 36, ,350 Energy bill savings 6,974 45,742 23,544 1,261 7,672 11,906 2,164 14,180 Simple payback (years) Table 7-7: Costs, carbon savings and energy bill savings for behaviour change, energy efficiency and building integrated renewable energy Behaviour change measures contribute significantly to the carbon reductions for the full retrofit approach (between 13 and 31%). These savings are similar to those achieved from the physical energy efficiency measures. However, they could be achieved at zero cost compared to the 26, ,000 required for the physical retrofit measures. For some building types, such as industrial buildings, the energy savings from behaviour change are much higher than for the physical 44

45 Section 7: Non-residential buildings retrofit measures, this is because the majority of the carbon emissions from the industrial buildings are from the energy required for the industrial process itself. There will be scope to upgrade the industrial equipment to make it more energy efficient. However, this will vary depending on the industrial process. Due to the size of some non-residential buildings, large arrays of solar photovoltaic panels can be installed which, if combined with the energy efficiency measures can more than offset the carbon emissions of the building (for example the public houses in Hackbridge). However, the costs of the solar photovoltaic panels are significantly more than the costs for the energy efficiency measures. The breakdown of this data into heat and electricity savings can be seen in Annex Light retrofit The installation of light retrofit measures (those that would attract Green Deal finance) was modelled to identify the costs and CO2 savings compared with a full retrofit. Based on the residential buildings in Hackbridge the following measures would qualify for Green Deal finance. Loft insulation (providing there is no existing loft insulation, where flat roof insulation was required this didn t meet the payback period). Draught-proofing New heating controls (programmer, start-stop optimisation, boiler thermostat) Reflective radiator panels Power-flush for radiators to remove sludge that makes the radiator less efficient Boiler or heater upgrade Thermostatic radiator valves De-stratification fans Lagging for the hot water cylinder Lagging for hot water pipe-work on external walls and floors Cavity wall insulation Building management system (for larger buildings) Rebalancing the heating system 45

46 Section 7: Non-residential buildings Heat exchange ventilation New refrigeration units IT shut-off Daylight sensors or dimming controls Light fitting upgrade (T12 to T5) Voltage optimisation Table 7-8 shows the average costs and carbon savings from the light retrofit measures described above (although not all those measures where appropriate for each building type) as well as the behaviour change measures listed in Section

47 Section 7: Non-residential buildings Halls/Schools Industrial Pubs High street shops Offices Warehouses Food shops Average Behaviour change % reduction in CO2e emissions 30% 31% 16% 19% 18% 13% 17% 21% Light retrofit Cost per building ( ) 32, ,487 5,995 3,873 21,768 25,764 4,061 41,607 % reduction in CO2e 22% 2% 17% 19% 34% 42% 17% 22% emissions Total Energy bill savings ( /year) 5,552 37,116 5,615 1,065 6,308 9, ,449 Payback (years) % reduction in CO2e emissions 53% 33% 32% 37% 52% 55% 34% 43% Table 7-8: Costs and percentage reduction in carbon emissions from light retrofit measures The costs of the light retrofit measures range between 3,873 for small high street shops and 197,487 for industrial buildings. However the higher costs for industrial buildings are in line with the vastly greater energy demands of the industrial buildings. Between 2% and 42% reduction in carbon emissions can be achieved from just the light retrofit efficiency measures. The payback periods for the combination of these measures is much lower than for the full retrofit approach, although this varies between building types depending on what measures were appropriate. 47

48 Section 9: New buildings in Hackbridge 8 New buildings in Hackbridge The London Borough of Sutton aspires to make Hackbridge, currently a local centre, into a district centre. The river Wandle that runs through Hackbridge was home to a number of mills in the 18 th century and the industrial presence remains in Hackbridge to this day. However, many of these industrial sites are now underutilised. Four of these industrial areas have been designated as re-development sites in the Hackbridge Masterplan (Figure 8-1 shows the proposed Masterplan): Felnex Trading Estate The Land North of Hackbridge Station Wandle Valley Trading Estate Kelvin House BedZED Felnex Trading Estate (the biggest of the development sites) was granted outline planning permission in Kelvin House (68 flats plus a ground floor retail unit) started construction in Together these four developments will double the amount of non-residential buildings in Hackbridge and increase the housing stock by 50%. Figure8-1: The proposed Masterplan for Hackbridge 48

49 Section 9: New buildings in Hackbridge Type of building Number Total floor area (m2) Houses ,424 Flats ,792 Employment 11 23,210 Care home 1 1,078 Retail 1 2,212 Supermarket 1 2,000 Community Total 1, ,494 Table 8-1: Number and floor area of new buildings planned in Hackbridge Table 8-1 shows the number of each type of new building planned across the different development types in Hackbridge. The new development will be mostly houses and flats, but a large amount of employment space (offices and workshops) is also planned. 8.1 Energy demand and carbon emissions from new buildings Table 8-2 shows what the energy demand from the new buildings would be, based on the buildings being built to 2010 Building Regulations. Although at the time of construction the buildings are likely to need to meet higher levels of carbon reduction based on the proposed updates to the Building Regulations 22 ; it is thought that this remaining reduction in carbon emissions will be achieved through the generation of renewable energy 23. The energy demand per m2 that these figures are based upon can be found in Annex 4. Building type Heat demand Electricity demand Total CO2e per unit (kwh/yr) per unit (kwh)/yr emissions (kgco2e/yr) Houses 6,664 3,332 3,349 Flats 5,831 3,634 3,374 Employment 153, ,142 97,724 Care home 72, , ,768 Retail 362,768 1,977,528 1,290,650 Supermarket 582,000 94, ,406 Community 81,690 16,571 26,074 Table 8-2: Energy and CO2 emissions from buildings in new developments in Hackbridge if built to 2010 Building Regulations 22 Department for Communities and Local Government. (2007) Building a Greener Future Policy Statement 23 Zero Carbon Hub. (2011) Carbon Compliance: Setting an appropriate limit for zero carbon new homes - Findings and Recommendations 49

50 Section 9: New buildings in Hackbridge 8.2 Maximum energy efficiency level with building integrated renewable energy generation If the new buildings were built to near Passivhaus standard and solar photovoltaic panels were installed, then the energy savings and reduction in carbon emissions would be as shown in Table 8-3. Building type Cost per unit( ) Energy savings (kwh/yr) % reduction in CO2e emissions /kgco2e saved Houses 33,041 5,931 86% 14 Flats 7,892 3,210 31% 11 Employment 914, ,345 39% 33 Care home 467,133 47,288 17% 26 Retail 958, ,513 7% 14 Supermarket 866, ,533 32% 21 Community 337,133 33,584 61% 29 Table 8-3: Costs, energy savings and CO2 savings from building to near Passivhaus standards with building integrated technologies. For the houses it is possible to achieve an 86% reduction in carbon emissions. However, this costs 14 per kgco2e saved. When compared with the cost of achieving carbon savings from retrofitting existing buildings this is an expensive way to save carbon. 50

51 Section 9: District energy 9 District energy In order to connect the existing buildings to the energy network planned in Hackbridge, the following infrastructure is required: High-pressure heat main to transfer the heat from the energy source along all the streets in Hackbridge. Pipework from the front door of the building to the high pressure heat main going along the street. A heat interface unit to deliver the heat to the building s central heating system and to allow the occupants to control the heating and hot water. The energy generation unit. For blocks of flats, pipework is required to connect each of the flats in the block to the heat main that enters the building. For buildings that currently have electric heating, a conversion to a wet heating distribution system would be required. Costs for each of these infrastructure requirements have been estimated in the proceeding sections. The full detail and methodology for calculating the costs associated with retrofitting a district energy system can be found in the Retrofitting District Heating report 24. A list of the assumptions used in estimating these costs can be found in Annex Pipe-work connecting each building to the main district heating network It has been planned that the new buildings in Hackbridge will be connected to an energy Figure 9-1: Proposed route of the energy network in Hackbridge 24 BioRegional (2011) Retrofitting District Heating Systems 51

52 Section 9: District energy network using waste heat from the existing landfill site. The expected cost of this network is 3,753, The principle heat main pipes proposed for the network can be seen in Figure 9-1 In order to establish the additional cost of connecting the existing buildings in Hackbridge to this energy network, the total length of the pipework required to run the length of all the streets in Hackbridge was calculated, the length of pipe-work required and the associated cost can be seen in Table 9-1. The cost of pipework per building was calculated by dividing the total cost of the pipework by the total number of buildings (2,484) that need to be connected to the network. Type of ground pipework is run through Cost per meter ( ) Total length (m) Total cost ( ) Soft 750 2,951 2,213,250 Cost of pipework per building ( ) 3, Connection Pipework is also required to go between the heat distribution main that runs along the street and each individual building (see Figure 9-2). Hard 1,000 8,189 8,189,000 Table 9-1: Cost of pipework from planned district heating network to all the existing buildings in Hackbridge For houses and non-residential buildings it has been estimated that on average 3 meters of pipework would be required. With a cost of 1,000 per meter, this would cost 3,000 per building. For flats, a heat exchanger would be required in each block of flats to transfer the heat from the network s hot water to a series of pipe-work which would connect each flat to the main heat exchanger. The cost of this heat exchanger and pipe-work would be in the region of 2,200 per flat. Figure 9-2: Schematic showing how each building would connect to the network 25 EC Harris. (2009) Hackbridge Sustainable Suburb Strategic Infrastructure and Building Cost Estimate 52

53 Section 9: District energy A heat exchanger would be required in each home/building to transfer the heat from the network s hot water to the cold water in the home/building s central heating system. The heat exchanger would be housed in a box alongside a heat meter (for billing) and the user controls; this whole unit is called the heat interface unit (see Figure 9-3) and is slightly smaller than a standard boiler. For homes/buildings which currently have radiators, hot water would be distributed around the building through the existing pipe-work and radiators. In flats which currently have electric storage heaters, pipework would need to be plumbed in to allow the hot water to be distributed. For flats this incurs an additional cost of 2,550 per flat. The costs associated with connecting each type of building to a district heating network are summarised Table 9-2. This does not include conversion from electric heating where this is required. Pipe-work for the Pipe-work between Heat interface Total cost main heat street level main and unit network in each home/building Hackbridge House 3,296 3,000 1,750 8,046 Figure 9-3: Picture of a heat interface unit 1 Flat 3,296 2,200 1,750 7,246 Non-residential building 3,296 3,000 2,485 8,781 Table 9-2: Costs associated with connecting existing buildings to a district heating network (per building) 9.3 Energy generation The different energy sources that are currently present in Hackbridge, or are proposed (which were described in Section 5.2) are shown in Table 9-3 along with their cost (that would need to be paid by the developer of an energy network), their potential energy generation and how much fuel would be required. 53