LB Greenwich - How low can we go?
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as PDF Our project has sought to produce a retrofit solution which is practical to build, easy to run and maintain, is cost effective and highly replicable to other similar properties. Achieving these aims will help enable social landlords like LB Greenwich, to roll out the solution across large numbers of existing dwellings. Our solution is based on applying Passivhaus standards of insulation and airtightness to the building envelope, with additional measures to further reduce energy demand, therefore limiting additional bolt-on technologies to provide that reduced energy demand. The 2bed extension required by LBG gives opportunities for improving performance and a model for other landlords with overcrowding of existing housing stock.
Retrofit for the future ZA137W
LB Greenwich - How low can we go? : Project images
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Energy and fuel use
Measured data from renewable generation is not yet available.
Fuel use
| Pre-development | Forecast | Measured | |
| Electricity use | 2155 kWh/yr | 1843 kWh/yr | - |
|---|---|---|---|
| Natural gas use | 59250 kWh/yr | - | - |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | 678 kWh/m².yr | 43 kWh/m².yr | - |
|---|---|---|---|
| Annual CO₂ emissions | 124 kg CO₂/m².yr | 10 kg CO₂/m².yr | - |
| Annual space heat demand | - | 20 kWh/m².yr | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| Renewables Technology | - | - |
| Other Renewables Tech | - | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | 43 kWh/m².yr | - |
| Annual CO₂ emissions offset by renewable generation | 10 kg CO₂/m².yr | - |
Calculation and targets
| Whole house energy calculation method | PHPP |
|---|---|
| Other whole house calculation method | - |
| Energy target | Retrofit for the Future |
| Other energy targets | - |
| Forecast heating load | 11.7 W/m² demand |
Airtightness
| Date | Result | |
| Pre-development air permeability test | - | 7.73m³/m².hr @ 50 Pascals |
|---|---|---|
| Final air permeability test | - | 0.57m³/m².hr @ 50 Pascals |
Project description
| Stage | Under construction |
|---|---|
| Start date | 19 April 2010 |
| Occupation date | 30 September 2010 |
| Location | Charlton, London London England |
| Build type | Refurbishment |
| Building sector | Public Residential |
| Property type | Semi-Detached |
| Construction type | Solid Brick |
| Other construction type | 215mm brick with external pebbledash render and brick plinth |
| Party wall construction | 215mm solid brick |
| Floor area | 108.4 m² |
| Floor area calculation method | Treated Floor Area (PHPP) |
| Building certification |
Project Team
| Organisation | Greenwich Council |
|---|---|
| Project lead person | London Borough of Greenwich |
| Landlord or Client | London Borough of Greenwich |
| Architect | Levitt Bernstein |
| Mechanical & electrical consultant | Thames Renewables Ltd /Sustainia Ltd |
| Energy consultant | The Healthy Home |
| Structural engineer | LB Greenwich |
| Quantity surveyor | LB Greenwich |
| Consultant | UEL |
| Contractor | Apollo |
Design strategies
| Planned occupancy | Seven people, only half of which will be out at work or school on weekdays |
|---|---|
| Space heating strategy | Air source heat pump and MHVR with additional electric radiant heater in bathroom operated by movement sensor. Heat recovered from kitchen and bathrooms. Incoming air will be taken at highest point of roof to avoid lower temperaures near ground level. |
| Water heating strategy | Water heated by air source heat pump - combined heating and hot water system. Top-up provided by 5.3m2 of solar thermal panels on south facing extension roof. |
| Fuel strategy | Mains electricity will be used to power the heat pump. An economy 10 tariff will be used in order to benefit from cheaper off peak electricity to heat the calorifier. The economy 10 tariff will allow a top up of heat in the afternoon if required |
| Renewable energy strategy | The Carbon Factor attached to photovoltaic generated electricity appeared to negate the suitability of PV. Micro wind was ruled out on the basis of local planning constraints and technical feasibility. 5.3m2 evacuated tube solar thermal to roof. |
| Passive Solar strategy | Glazed window and door openings are maximised to the west and south aspects, taking advantage of the extension to provide some limited south facing wall. |
| Space cooling strategy | Natural ventilation for the majority of the cooling season. Additional low power fan allows for reversal of Genvex system in summer to provide responsive night time cooling when required. |
| Daylighting strategy | Windows to the west and south have been maximised in size. Where a room has become deeper and in another a window has reduced in size a sunpipe has been dropped into the back of each room to maximise natural daylight. |
| Ventilation strategy | Mechanical ventilation with heat recovery in colder months. Natural cross-ventilation during warmer months. |
| Airtightness strategy | New ground floor concrete slab provides air tight junction with existing walls. High perfrmance windows and doors to be installed, including triple glazed to north and east. Roof to be insulated at rafter level with appopriate airtight membrane. New enclosed porch to front door to reduce heat loss through door. |
| Strategy for minimising thermal bridges | External insulation of walls and chimneys, perimeter insulation to new ground floor slab and overlap with external wall insulation, insulated reveal details to window and doors, new enclosed porch to minimise problems with front door frame/wall return. External insulation will continue down to footings, a depth of 0.5 to 1.0 metre below ground level |
| Modelling strategy | Modelling has been carried out using PHPP to provide whole house energy consumption data. SAP has been used as required by the competition guidelines for comparative purposes. The existing building was also modelled in PHPP to provide CO2 saving analysis and current fuel consumption data. |
| Insulation strategy | Below slab insulation to new ground floor to achieve 0.13 W/m2K U-value. External rendered wall insulation to achieve 0.1W/m2K Chimneys to be insulated and rendered externally. Roof insulation between and below rafters to give warm roof space to 0.1W/m2K U-value |
| Other relevant retrofit strategies | Measures should be easy to run and maintain. The passive strategy reduces the reliance on technology and will be easier to understand and operate to optimum performance by tenants. |
| Contextual information | The house was included as part of the council extension program after its selection for the Retrofit competition and identified for 2 additional bedrooms. This has provided some opportunities, for example to provide some limited south facing windows, and maximise west facing glazing, but also has meant a more difficult analysis of costings for example. |
Building services
| Occupancy | NULL |
|---|---|
| Space heating | NULL |
| Hot water | NULL |
| Ventilation | NULL |
| Controls | NULL |
| Cooking | NULL |
| Lighting | NULL |
| Appliances | NULL |
| Renewable energy generation system | NULL |
| Strategy for minimising thermal bridges | NULL |
Building construction
| Storeys | |
|---|---|
| Volume | - |
| Thermal fabric area | - |
| Roof description | NULL |
| Roof U-value | 0.00 W/m² K |
| Walls description | NULL |
| Walls U-value | 0.00 W/m² K |
| Party walls description | NULL |
| Party walls U-value | 0.00 W/m² K |
| Floor description | NULL |
| Floor U-value | 0.00 W/m² K |
| Glazed doors description | NULL |
| Glazed doors U-value | 0.00 W/m² K - |
| Opaque doors description | NULL |
| Opaque doors U-value | 0.00 W/m² K - |
| Windows description | NULL |
| Windows U-value | 0.00 W/m² K - |
| Windows energy transmittance (G-value) | - |
| Windows light transmittance | - |
| Rooflights description | NULL |
| Rooflights light transmittance | - |
| Rooflights U-value | 0.00 W/m² K |