Dartmouth Avenue

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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.
Images Graphs Figures Description Strategies Building

Dartmouth Avenue : Project images

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CO2 emissionsPrimary energy requirement
Energy target
EcoHomes Excellent

Energy and fuel use

Fuel use by type
Primary energy requirement
CO2 emissions

Measured data from renewable generation is not yet available.

Fuel use

Electricity use - - 3684 kWh/yr
Natural gas use- - 6162 kWh/yr
Oil use- - -
LPG use- - -
Wood use- - -
Other Fuel - - -
Primary energy requirement - - 185 kWh/m².yr
Annual CO₂ emissions - - 39 kg CO₂/m².yr
Annual space heat demand - - -

Renewable energy

Electricity generationForecastMeasured
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 -


Pre-development air permeability test--
Final air permeability test-3m³/m².hr @ 50 Pascals

Project description

Start date
Occupation date31 January 2005
Location Woking Surrey  England
Build typeNew build
Building sectorPublic Residential
Property typeSemi-Detached
Construction typeSoftwood frame
Other construction type
Party wall construction
Floor area 88
Floor area calculation method Actual Floor Area (SAP)
Building certification

Project Team

Project lead person
Landlord or ClientGreen Oak Housing Association
ArchitectJon Broome
Mechanical & electrical consultant
Energy consultant
Structural engineer
Quantity surveyor

Design strategies

Planned occupancyMix of 2-4 bed dwellings.
Space heating strategyLow NOx, gas combi boilers were used and fed a conventional radiator heating system in each house.
Water heating strategyGas combi boilers supply the hot water.
Fuel strategyMains gas and electricity.
Renewable energy strategy
Passive Solar strategy
Space cooling strategy
Daylighting strategyThe improved comfort from triple glazing meant that large windows could be installed for daylight.
Ventilation strategyMechanical 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 strategySAP/NHER
Insulation strategy
Other relevant retrofit strategies
Contextual information

Building services

OccupancyVaries from 2 bed to 4 bed dwellings. Average 20m2/person
Space heatingConventional radiator heating is used, with a low NOx condensing combi gas boiler in each house.
Hot waterA condensing combi gas boiler in each house provides hot water.
VentilationMechanical 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.
LightingLow energy compact fluorescent lighting was used throughout.
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 -

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