Crawley Homes Cornish Unit retrofit upgrade
Download
as PDF Our chosen approach to energy saving and CO2 reduction in the Cornish unit is to follow a lean-clean-green hierarchy: seeking to minimise heat losses from the property 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 external mineral wool insulation, internal Spacetherm insulation, triple-glazed windows and doors, heat recovery ventilation with a retrofit airtightness strategy, low energy lighting, PV and a micro-CHP heating and distribution system.
Retrofit for the future ZA586R
Crawley Homes Cornish Unit retrofit upgrade : Project images
Click on image to preview full size
Energy and fuel use
Measured data from renewable generation is not yet available.
Fuel use
| Pre-development | Forecast | Measured | |
| Electricity use | 3977 kWh/yr | 2255.94 kWh/yr | - |
|---|---|---|---|
| Natural gas use | 17060 kWh/yr | 7356.72 kWh/yr | - |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | 326 kWh/m².yr | 156 kWh/m².yr | - |
|---|---|---|---|
| Annual CO₂ emissions | 65 kg CO₂/m².yr | 31 kg CO₂/m².yr | - |
| Annual space heat demand | - | 47 kWh/m².yr | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| Micro CHP low carbon fuel | 698 kWh/yr | - |
| PV | 1210.459961 kWh/yr | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | 103 kWh/m².yr | - |
| Annual CO₂ emissions offset by renewable generation | 19 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 | 19 W/m² demand |
Airtightness
| Date | Result | |
| Pre-development air permeability test | - | 10.25m³/m².hr @ 50 Pascals |
|---|---|---|
| Final air permeability test | - | 5.48m³/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 | Concrete frame + twin skin concrete infil panel + mansard roof |
| Party wall construction | Concrete frame + twin skin concrete infil panel |
| Floor area | 90.6 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 lioan 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 - Couple with a small child, all out during the week |
|---|---|
| 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 1.4 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 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 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 - At ground floor the existing concrete panel walls will be externally insulted to achieve a U-value of 0.15 w/m2K. At first |
| 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 Cornish 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 |