Crawley New Town retrofit
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as PDF This property is one of many cavity wall contructed dwellings found in Crawley new town now considered to be traditional . Our chosen approach to energy saving and CO2 reduction is to follow a lean-clean-green hierarchy: seeking to minimise heat losses from the thermal fabric and ventilation method; to supply residual space and water heating using replicable, low carbon technology; to minimise lighting energy loads; and finally to consider micro-generation using proven, renewable energy systems. The package of measures proposed to achieve these targets included aerogel dry-lining insulation, triple-glazed windows and doors, MVHR with a retrofit airtightness strategy, low energy lighting, PV and a micro-CHP heating.
Retrofit for the future ZA631J
Crawley New Town retrofit : 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 | 1051 kWh/yr | 2229.12 kWh/yr | - |
|---|---|---|---|
| Natural gas use | 7411 kWh/yr | 5422.48 kWh/yr | - |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | 144 kWh/m².yr | 153 kWh/m².yr | - |
|---|---|---|---|
| Annual CO₂ emissions | 28 kg CO₂/m².yr | 31 kg CO₂/m².yr | - |
| Annual space heat demand | - | 39.9 kWh/m².yr | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| PV | 1751 kWh/yr | - |
| Micro Gas Fired CHP | 568 kWh/yr | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | 78 kWh/m².yr | - |
| Annual CO₂ emissions offset by renewable generation | 13 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 | 16.3 W/m² demand |
Airtightness
| Date | Result | |
| Pre-development air permeability test | - | 5.65m³/m².hr @ 50 Pascals |
|---|---|---|
| Final air permeability test | - | 3.64m³/m².hr @ 50 Pascals |
Project description
| Stage | Under construction |
|---|---|
| Start date | 01 February 2010 |
| Occupation date | 28 June 2010 |
| Location | Crawley West Sussex England |
| Build type | Refurbishment |
| Building sector | Public Residential |
| Property type | End Terrace |
| Construction type | Masonry Cavity |
| Other construction type | |
| Party wall construction | Solid masonry wall |
| Floor area | 77.4 m² |
| Floor area calculation method | Treated Floor Area (PHPP) |
| Building certification |
Project Team
| Organisation | Crawley Borough Council |
|---|---|
| Project lead person | Crawley Homes, Town Hall, The Boulevard, West Sussex, RH10 1UZ |
| Landlord or Client | Crawley Homes, Town Hall, The Boulevard, West Sussex, RH10 1UZ |
| Architect | Energy Conscious design, Studio 3, Blue lion Place 237 Long Lane, London SE1 4PU |
| Mechanical & electrical consultant | Environmental Design Associates, 31 Wick Road, Teddington, Middlesex, TW11 9DN |
| Energy consultant | ECD Project Services, Studio 3, Blue lion Place 237 Long Lane, London SE1 4PU |
| Structural engineer | Carter Clack Partnership, 49 Romney Street, Westminster, London, SW1P 3RF |
| Quantity surveyor | The Keegans Group, Studio 2, 193-197 Long Lane, London, SE1 4PD |
| Consultant | Public Participation, Consultation and Research, Studio 2, 193-197 Long Lane, London, SE1 4PD |
| Contractor | The Apollo Group, Conquest House, Church Street, Waltham Abbey, Essex, EN9 1DX |
Design strategies
| Planned occupancy | Existing tenants - Elderly couple at home weekdays |
|---|---|
| Space heating strategy | Heating will be provided by mains gas via a micro CHP unit utilising existing radiators. Heat will be recovered from exhaust air via the use of mechanical ventilation with high efficiency heat recovery unit. |
| Water heating strategy | Hot water will be provided by mains gas via a micro CHP unit utilising existing hot water cylinder |
| Fuel strategy | Mains Gas, Mains electricity |
| Renewable energy strategy | Onsite electric production by 2.1 kWp photovoltaic panels and low carbon electricity production via gas fired micro CHP unit. |
| Passive Solar strategy | Window fenestration has been simplified in proposed replacement windows to maximise solar gain. |
| Space cooling strategy | MVHR with summer bypass combined with natural ventilation for summer period. Night purging during heat waves. |
| Daylighting strategy | Window fenestration has been simplified in proposed replacement windows to maximise day light. |
| Ventilation strategy | Mechanical ventilation with heat recovery and additional natural ventilation by opening windows during summer months as required. |
| Airtightness strategy | All existing vents and chimneys blocked up. New air barrier created by OSB board at ceiling level with taped joints and perimeters taped to masonry walls and plastered over. Service void created bellow this to eliminated penetrations. Windows, floors, junctions and all penetrations sealed with proprietary air tight tapes, membranes and grommets. All voids such as cavities filled to mitigate thermal bypass. |
| Strategy for minimising thermal bridges | Continuous insulation maintained throughout. Geometric thermal bridges minimised. Junctions assessed include: Ground floor junction, external corner, party wall, party roof, party floor, eaves, verge, window jamb, head and sill, door jamb, head and threshold. Internal insulation has been returned on party walls. |
| Modelling strategy | Whole house modeling was undertaken in both PHPP and SAP, with the use of extension sheets for both. The results provided for existing energy usage were calculated in SAP, as this software is more suitable for modeling poor performing buildings. The proposed results were modeled in PHPP as this software is more accurate for predicating energy usage in high performing buildings. Dynamic simulation was used to assess the impact of our proposed micro CHP heating system with the results fed back into PHPP/SAP. |
| Insulation strategy | - The existing solid floor will be insulted with a thin layer of aerogel laminated chipboard to achieve a U-value of 0.38 w/m2K - The existing cavity walls will be filled with insulation and dry lined internally with an aerogel laminated board to provid |
| Other relevant retrofit strategies | We propose to fit an intelligent heating controller designed to save energy and improve comfort in residential buildings. The system controls both central and water heating, reducing energy consumption by automatically monitoring and learning occupant behavior and preferences. It also provides an easy to use and simply user interface as well as covering all energy monitoring requirements. |
| Contextual information | Crawley was one of the original eight new towns around London aimed at getting people to move from the over-crowded capital into the countryside. To get such massive housing expansion off the ground, the Government-appointed development corporations to deliver the large numbers of dwellings required. By far the vast majority of these were constructed in brick/block cavity construction, using an often repeated layout that is now considered to be 'traditional' for Crawley New Town. These developments are now managed by Crawley Homes. This project will therefore focus on the most prevalent housing archetype and will seek to establish a complementary and replicable set of measures which significantly reduce energy use and CO2 emissions. |
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 |