Larch House, Ebbw Vale, Wales
Download
as PDF The Larch House, designed by bere:architects, is the UKs first zero carbon (code 6), low cost, Certified Passivhaus, built as prototype social housing and launched at the National Eisteddfod for Wales in 2010.The three bedroom house is 1000ft above sea level in an exposed and misty hilltop location in Ebbw Vale. In spite of this, most energy needs are met by heat from the sun, occupants and appliances and the house generates as much energy from the sun, from solar thermal and photovoltaic panels as well as by glazing, as it uses for the whole year making it Zero Carbon by UK definition and showing how we can live comfortably with minimal impact on the natural world.The house achieved the UK's best air test for a free standing house with ...
Larch House, Ebbw Vale, Wales : Project images
Click on image to preview full size
Fuel use
| Pre-development | Forecast | Measured | |
| Electricity use | - | 1644 kWh/yr | - |
|---|---|---|---|
| Natural gas use | - | 2662 kWh/yr | - |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | - | 82 kWh/m².yr | - |
|---|---|---|---|
| Annual CO₂ emissions | - | 17 kg CO₂/m².yr | - |
| Annual space heat demand | - | 12.9 kWh/m².yr | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| Photovoltaics | 3846 kWh/yr | - |
| Other Renewables Tech | - | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | -29 kWh/m².yr | - |
| Annual CO₂ emissions offset by renewable generation | -9 kg CO₂/m².yr | - |
Calculation and targets
| Whole house energy calculation method | PHPP |
|---|---|
| Other whole house calculation method | - |
| Energy target | |
| Other energy targets | - |
| Forecast heating load | 10.7 W/m² demand |
Airtightness
| Date | Result | |
| Pre-development air permeability test | - | - |
|---|---|---|
| Final air permeability test | - | - |
Project description
| Stage | Under construction |
|---|---|
| Start date | 01 March 2010 |
| Occupation date | 01 August 2010 |
| Location | Ebbw Vale Blaenau Gwent Wales |
| Build type | New build |
| Building sector | Public Residential |
| Property type | Detached |
| Construction type | Other |
| Other construction type | Timber frame construction |
| Party wall construction | |
| Floor area | 87 m² |
| Floor area calculation method | Treated Floor Area (PHPP) |
| Building certification |  Passivhaus certified building |
Project Team
| Organisation | bere:architects |
|---|---|
| Project lead person | bere:architects |
| Landlord or Client | United Welsh Housing Association |
| Architect | bere:architects |
| Mechanical & electrical consultant | Alan Clarke |
| Energy consultant | Rob McLeod (BRE) |
| Structural engineer | Bob Johnson |
| Quantity surveyor | e-Griffin Consulting |
| Consultant | |
| Contractor | Pendragon |
Design strategies
| Planned occupancy | 4 - 5 people |
|---|---|
| Space heating strategy | A heat recovery ventilation ensures not only fresh air but also recovers the heat from the extraction. Additionally if needed there are two towel radiators installed in each bathroom. |
| Water heating strategy | A solar thermal is in place to heat the domestic hot water. There is a gas condensing boiler for back up. |
| Fuel strategy | Mains gas. Mains electricity |
| Renewable energy strategy | 2.52kWp of Photovoltaics are installed. |
| Passive Solar strategy | The rear elevation faces South and the large southern elevation to maximise solar gains. |
| Space cooling strategy | Natural cross and stack ventilation will ensure that the Welsh Passivhaus stays cool during the summer time. |
| Daylighting strategy | The Welsh Passivhaus benefits from large window openings. The house is shallow enough to maximise day-lighting. The kitchen achieves a minimum average daylight factor of at least 2% and the living rooms achieve average daylight factor of at least 1.5% |
| Ventilation strategy | Comfort ventilation with 92% heat recovery (winter)Natural ventilation with extract only in the Summer |
| Airtightness strategy | OSB with taped joints and an intello membrane. Passivhaus detailing around windows and other openings. Particular care and supervision of M&E penetrations. Careful detailing and site supervision.Preliminary testing to help site identify air leakage routes. |
| Strategy for minimising thermal bridges | Bridge-free construction throughout and all junctions have been modelled in Heat2 and the results fed into the PHPP. |
| Modelling strategy | Every junction of the building was optimised using a thermal modelling programm and then fed back into the Passivhaus Planning Package. |
| Insulation strategy | External wall : timber frame with 280mm of mineral wool insulation in between the studs, with a 100mm service void on the inside with wood fibre insulation and a 100mm rigid wood fibre insulation layer on the outside (U-value = 0.095 W/m2K)Roof: 560mm of mineral wool insulation on top of the first floor ceiling (U-value = 0.074 W/m2K)Floor slab: 480mm of EPS insulation under the concrete slab (U-value = 0.076 W/m2K). |
| Other relevant retrofit strategies | |
| Contextual information |
Building services
| Occupancy | |
|---|---|
| Space heating | |
| Hot water | |
| Ventilation | |
| Controls | |
| Cooking | |
| Lighting | |
| Appliances | |
| Renewable energy generation system | |
| Strategy for minimising thermal bridges |
Building construction
| Storeys | |
|---|---|
| Volume | - |
| Thermal fabric area | - |
| Roof description | |
| Roof U-value | - |
| Walls description | |
| Walls U-value | - |
| Party walls description | |
| Party walls U-value | - |
| Floor description | |
| Floor U-value | - |
| Glazed doors description | |
| Glazed doors U-value | - - |
| Opaque doors description | |
| Opaque doors U-value | - - |
| Windows description | |
| Windows U-value | - - |
| Windows energy transmittance (G-value) | - |
| Windows light transmittance | - |
| Rooflights description | |
| Rooflights light transmittance | - |
| Rooflights U-value | - |