Grayshott, Surrey
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as PDF Refurbishment and extension of 1962 detached cavity wall house using external woodfibre insulation system, triple glazed windows, and mechanical extract ventilation.
Grayshott, Surrey : 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 | - | - | - |
|---|---|---|---|
| Natural gas use | - | - | - |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | - | - | - |
|---|---|---|---|
| Annual CO₂ emissions | - | - | - |
| Annual space heat demand | 278 kWh/m².yr | 35 kWh/m².yr | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| PV array | 3000 kWh/yr | - |
| Other Renewables Tech | - | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | -49 kWh/m².yr | - |
| Annual CO₂ emissions offset by renewable generation | -12 kg CO₂/m².yr | - |
Calculation and targets
| Whole house energy calculation method | PHPP |
|---|---|
| Other whole house calculation method | - |
| Energy target | AECB Silver |
| Other energy targets | - |
| Forecast heating load | 17 W/m² demand |
Airtightness
| Date | Result | |
| Pre-development air permeability test | 30 July 2012 | 9.88m³/m².hr @ 50 Pascals |
|---|---|---|
| Final air permeability test | 02 December 2013 | 2.5m³/m².hr @ 50 Pascals |
Project description
| Stage | Under construction |
|---|---|
| Start date | 15 January 2013 |
| Occupation date | 16 February 2014 |
| Location | Grayshott, Hampshire/Surrey border Hampshire England |
| Build type | Refurbishment |
| Building sector | Private Residential |
| Property type | Detached |
| Construction type | Masonry Cavity |
| Other construction type | 100mm block, 60mm cavity, 100mm brick. Part cavity filled. |
| Party wall construction | |
| Floor area | 152.7 m² |
| Floor area calculation method | Treated Floor Area (PHPP) |
| Building certification |  AECB silver standard certified building |
Project Team
| Organisation | Conker Conservation Ltd |
|---|---|
| Project lead person | Paul Mallion |
| Landlord or Client | Mr and Mrs Sims |
| Architect | Conker Conservation Ltd |
| Mechanical & electrical consultant | - |
| Energy consultant | Conker Conservation Ltd |
| Structural engineer | |
| Quantity surveyor | |
| Consultant | Kithurst Builders |
| Contractor | Contract Management Company |
Design strategies
| Planned occupancy | Two people, at work or working from home, with elderly relative living in annexe. |
|---|---|
| Space heating strategy | High efficiency thermal mass wood stove.Trial of low energy electric radiant panels embedded into walls, on separate circuit to allow monitoring. |
| Water heating strategy | Direct hot water cylinder with twin immersion elements, one linked to PV via Immersun controller to optimise solar heating of cylinder. |
| Fuel strategy | Wood heating, with electric radiant panels as back up, fueled by solar PV via Immersun.PV switch. |
| Renewable energy strategy | PV |
| Passive Solar strategy | Property has perfect south front facade. South facing windows enlarged to capitalise. New west facing windows and doors added to gain late afternoon sun into living spaces. |
| Space cooling strategy | Cross ventilation provided by new windows at first floor, and large openable internal doors to create air flow. |
| Daylighting strategy | Very well provided for as existing, being of partly open plan and large window as fashionable in 1960s. New west facing windows to replace north facing units, to balance heat losses. |
| Ventilation strategy | Constant running individual low energy extracts in wet rooms. |
| Airtightness strategy | Comprehensive survey done at commencement identified cavity as a leakage, along with defective windows. Replastering over airtight membranes, Siga and ProClima tapes and membranes used. |
| Strategy for minimising thermal bridges | Careful assessment of each area from plans. Solutions include internal, external and cavity insulation. |
| Modelling strategy | PHPP, with site specific climate data provided by BRE due to local conditions, height above sea level. |
| Insulation strategy | External woodfibre insulation system by Steico with Lime Green render to existing cavity walls. New timber frame using 150mm wool between studs, woodfibre outside.PU insulation laid over existing floors. 300mm loft insulation. 100mm XPS to walls below DPC externally. |
| Other relevant retrofit strategies | Additional thermal mass built in where possible, such as sun space floor slab. Electric solar PV fueled wall heating being trialled.... |
| Contextual information |
Building services
| Occupancy | As design |
|---|---|
| Space heating | As design, plus electric towel rails in three wet rooms, linked to timer and thermostat. |
| Hot water | As design |
| Ventilation | As design |
| Controls | Individual switch and thermostatic control over radiant wall heaters. |
| Cooking | Conduction hob and electric oven, and a good coffee machine, natch. |
| Lighting | Mostly LED, small number of localised halogen spots, corridors using compact fluorescent. |
| Appliances | |
| Renewable energy generation system | PV array on main south roof slope |
| Strategy for minimising thermal bridges | Details that have been previously approved on PH projects have been used, but not specifically calculated. Approximate but safe values used in calculations. |
Building construction
| Storeys | 2 |
|---|---|
| Volume | 481m³ |
| Thermal fabric area | 456 m² |
| Roof description | Standard trussed rafters at 600mm centres, 2 layers of 150mm natural sheeps wool insulation |
| Roof U-value | 0.14 W/m² K |
| Walls description | Cavity walls filled with mineral wool, external 120mm woodfibre insulation. New walls 150mm timber stud insulated with 80mm woodfibre insulation externally, voids filled with wool, U value 0.18. |
| Walls U-value | 0.25 W/m² K |
| Party walls description | |
| Party walls U-value | - |
| Floor description | Existing concrete floor slab upgraded with 50mm PU insulation and floating floor. |
| Floor U-value | 0.30 W/m² K |
| Glazed doors description | Katzbeck timber clad timber framed units, triple glazed. |
| Glazed doors U-value | 0.99 W/m² K installed |
| Opaque doors description | |
| Opaque doors U-value | - - |
| Windows description | Katzbeck Linea aluminium clad timber framed units, tilt and turn with trickle vent in head. |
| Windows U-value | 0.91 W/m² K - |
| Windows energy transmittance (G-value) | 0.5 % |
| Windows light transmittance | 0.6% |
| Rooflights description | |
| Rooflights light transmittance | - |
| Rooflights U-value | - |