SNW Home retrofit - Crawley
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as PDF This property is typical non-traditional or system built 3-bedroom property built in 1968. The proposed package of thermal insulation upgrades will go far beyond basic provision carried out to date, using ECD Architects retrofit experience to comprehensively address thermal bridging concerns and fabric air tightness whilst simultaneously employing advanced insulation materials to address heat loss. The whole house approach will also include market leading replacement fenestration. MVHR and cutting edge micro-generation technology in the form of both Combined Heat & Power and photovoltaics.
Retrofit for the future ZA592C
SNW Home retrofit - Crawley : 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 | 2968 kWh/yr | 1883.25 kWh/yr | - |
|---|---|---|---|
| Natural gas use | 27631 kWh/yr | 5900.85 kWh/yr | - |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | 468 kWh/m².yr | 137 kWh/m².yr | - |
|---|---|---|---|
| Annual CO₂ emissions | 89 kg CO₂/m².yr | 28 kg CO₂/m².yr | - |
| Annual space heat demand | - | 37 kWh/m².yr | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| PV | 1120 kWh/yr | - |
| Micro CHP Low Carbon Energy | 587 kWh/yr | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | 86 kWh/m².yr | - |
| Annual CO₂ emissions offset by renewable generation | 16 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 | 17.2 W/m² demand |
Airtightness
| Date | Result | |
| Pre-development air permeability test | - | 11.62m³/m².hr @ 50 Pascals |
|---|---|---|
| Final air permeability test | - | 7.77m³/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 | Other |
| Other construction type | SNW unit. System built concrete panels with timber frame infill |
| Party wall construction | SNW unit. System built concrete panels with timber frame infill |
| Floor area | 83.7 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 | Exisitng Tennant - 1 person at work 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. |
| 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 walls will be clad externally with a combination of vacuum insulted panels and rigid phenolic board, giving a U |
| Other relevant retrofit strategies | Fitting 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 who often looked to exploit the programme benefits of non-traditional forms of construction. Crawley saw a number of sites developed using these systems in the 1950s and 1960s, which still exist today and are now managed by Crawley Homes. This project will therefore focus on one such housing archetype - the SNW Unit - 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 |