Dartmouth Avenue
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as PDF The first of three schemes undertaken by Greenoak Housing Association and architect Jon Broome. The aim was to develop a replicable model to reduce emissions and other environmental impacts in mainstream housing by incorporating cost effective and trouble free measures. The emphasis is on reducing energy demand by creating a well insulated and airtight envelope. The properties in this development range in size from 80m2 2 bed dwellings to 108m2 4 bed dwellings. The average floor area and energy use per dwelling has been used in this entry.
Dartmouth Avenue : 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 | - | - | 3684 kWh/yr |
|---|---|---|---|
| Natural gas use | - | - | 6162 kWh/yr |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | - | - | 185 kWh/m².yr |
|---|---|---|---|
| Annual CO₂ emissions | - | - | 39 kg CO₂/m².yr |
| Annual space heat demand | - | - | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| Renewables Technology | - | - |
| Other Renewables Tech | - | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | - | 185 kWh/m².yr |
| Annual CO₂ emissions offset by renewable generation | - | 39 kg CO₂/m².yr |
Calculation and targets
| Whole house energy calculation method | |
|---|---|
| Other whole house calculation method | - |
| Energy target | EcoHomes Excellent |
| Other energy targets | - |
| Forecast heating load | - |
Airtightness
| Date | Result | |
| Pre-development air permeability test | - | - |
|---|---|---|
| Final air permeability test | - | 3m³/m².hr @ 50 Pascals |
Project description
| Stage | Occupied |
|---|---|
| Start date | |
| Occupation date | 31 January 2005 |
| Location | Woking Surrey England |
| Build type | New build |
| Building sector | Public Residential |
| Property type | Semi-Detached |
| Construction type | Softwood frame |
| Other construction type | |
| Party wall construction | |
| Floor area | 88 m² |
| Floor area calculation method | Actual Floor Area (SAP) |
| Building certification |
Project Team
| Organisation | |
|---|---|
| Project lead person | |
| Landlord or Client | Green Oak Housing Association |
| Architect | Jon Broome |
| Mechanical & electrical consultant | |
| Energy consultant | |
| Structural engineer | |
| Quantity surveyor | |
| Consultant | |
| Contractor |
Design strategies
| Planned occupancy | Mix of 2-4 bed dwellings. |
|---|---|
| Space heating strategy | Low NOx, gas combi boilers were used and fed a conventional radiator heating system in each house. |
| Water heating strategy | Gas combi boilers supply the hot water. |
| Fuel strategy | Mains gas and electricity. |
| Renewable energy strategy | |
| Passive Solar strategy | |
| Space cooling strategy | |
| Daylighting strategy | The improved comfort from triple glazing meant that large windows could be installed for daylight. |
| Ventilation strategy | Mechanical extract ventilation (MEV) with continuous extract from bathroom and kitchen, with humidity controlled wall inlets. The bathroom extract grilles include PIR detectors to boost extract when rooms are occupied, and there is a boost switch to increase air flow when cooking. |
| Airtightness strategy | Large, pre-fabricated timber frame panels (to minimise the number of joins) with internal airtightness membranes. |
| Strategy for minimising thermal bridges | The timber frame panels designed with insulation zones abutting at corners and eaves. The large panels mean there is less doubling up of structure at panel joints than typical pre-fabricated timber frame designs. The design also includes cross battening of the 50mm battens which increase the insulation from the standard 140mm frame depth. |
| Modelling strategy | SAP/NHER |
| Insulation strategy | |
| Other relevant retrofit strategies | |
| Contextual information |
Building services
| Occupancy | Varies from 2 bed to 4 bed dwellings. Average 20m2/person |
|---|---|
| Space heating | Conventional radiator heating is used, with a low NOx condensing combi gas boiler in each house. |
| Hot water | A condensing combi gas boiler in each house provides hot water. |
| Ventilation | Mechanical extract ventilation (MEV) by Aerco Ventilation Ltd. This was continuous extract from bathroom and kitchen, with humidity controlled wall inlets. The bathroom extract grilles include PIR detectors to boost extract when rooms are occupied, and there is a boost switch to increase air flow when cooking. |
| Controls | |
| Cooking | Gas |
| Lighting | Low energy compact fluorescent lighting was used throughout. |
| Appliances | |
| Renewable energy generation system | |
| Strategy for minimising thermal bridges |
Building construction
| Storeys | 2 |
|---|---|
| Volume | - |
| Thermal fabric area | - |
| Roof description | The roof insulation is cellulose between 300mm timber I-beam rafters, topped with bitumen impregnated fibreboard. Internally plasterboard is fixed directly to the I-beams with a vapour control layer forming the air barrier. A service void is not required as all pipes, wires and ducts are run through the open web joists of the first floor construction and wall lights only are used on the upper floor. A warm mezzanine was formed over the upper floor, providing storage space to the bedrooms. |
| Roof U-value | 0.14 W/m² K |
| Walls description | The walls are timber frame, 140mm x 50mm studs with 50x50 counter battens to the inside, fully filled with cellulose insulation behind a lining of oriented strand board (OSB) sheets. External finish is a 15mm bitumen fibreboard, breather membrane, 25mm battened cavity and lime render on stainless steel mesh. Some areas use natural finish timber cladding instead of render. Internally the OSB layer is sealed with a vapour control membrane also forming the air barrier. After installation a cross-battened 25mm service void is formed behind the plasterboard. This development was built from large pre-fabricated panels. |
| Walls U-value | 0.19 W/m² K |
| Party walls description | |
| Party walls U-value | - |
| Floor description | The floor is suspended timber inprefabricated panels. The construction uses LVL (laminated veneer lumber) beams to span the pile caps, with the floor made of 300mm composite timber I-beams at 600 centres, filled with cellulose insulation enclosed by bitumen fibreboard below and OSB above. A gas-proof membrane between OSB and ply flooring provides the airbarrier. |
| Floor U-value | 0.12 W/m² K |
| Glazed doors description | |
| Glazed doors U-value | - - |
| Opaque doors description | |
| Opaque doors U-value | - - |
| Windows description | Triple glazed windows are used, with wooden frames seen internally but clad with aluminium externally to minimise maintenance. |
| Windows U-value | 1.30 W/m² K - |
| Windows energy transmittance (G-value) | - |
| Windows light transmittance | - |
| Rooflights description | |
| Rooflights light transmittance | - |
| Rooflights U-value | - |