Rectory Cottage
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as PDF Rectory Cottage is an EnerPhit-certified retrofit stone cottage. Energy performance measures include excavating the original floor to insert insulation (the builders were ex-miners), external wall insulation, triple glazed windows and doors, and a ventilation and heat recovery system. An LPG system boiler and solar thermal panels with integrated controllers were installed. To add to the PHPP challenges the building is in a National Park and a conservation area, and also accommodates the occasional bat....externally. The renovations were designed by a PHPP consultant and experienced architect and the work was carried out by a novice builder and client. Gas meters have been installed which, together with temperature and humidity sensors, will be used to determine the building performance.
Rectory Cottage : 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 | - | 25 kWh/m².yr | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| Renewables Technology | - | - |
| Other Renewables Tech | - | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | - | - |
| Annual CO₂ emissions offset by renewable generation | - | - |
Calculation and targets
| Whole house energy calculation method | PHPP |
|---|---|
| Other whole house calculation method | - |
| Energy target | EnerPHit |
| Other energy targets | - |
| Forecast heating load | 12 W/m² demand |
Airtightness
| Date | Result | |
| Pre-development air permeability test | - | - |
|---|---|---|
| Final air permeability test | 24 March 2015 | 0.62m³/m².hr @ 50 Pascals |
Project description
| Stage | Occupied |
|---|---|
| Start date | |
| Occupation date | |
| Location | Llangattock Powys Wales |
| Build type | Refurbishment |
| Building sector | Private Residential |
| Property type | Detached |
| Construction type | Stone |
| Other construction type | with blockwork extensions |
| Party wall construction | |
| Floor area | 141 m² |
| Floor area calculation method | Treated Floor Area (PHPP) |
| Building certification |  Passivhaus certified building |
Project Team
| Organisation | |
|---|---|
| Project lead person | Peter Blood |
| Landlord or Client | Mr and Mrs P Blood |
| Architect | Simon Brown |
| Mechanical & electrical consultant | |
| Energy consultant | Alan Clarke |
| Structural engineer | |
| Quantity surveyor | |
| Consultant | |
| Contractor | Craig Morgan |
Design strategies
| Planned occupancy | |
|---|---|
| Space heating strategy | LPG system boiler with programmable controller, fuelled by 47 kg cylinders. |
| Water heating strategy | Twin coil cylinder heated by boiler and solar thermal panels with integrated controllers. |
| Fuel strategy | No town gas, so opted for LPG cylinders as a more compact solution than oil. |
| Renewable energy strategy | Solar PV on adjacent outbuilding, not part of retrofit. |
| Passive Solar strategy | A further south-facing window was added in the refurbishment. Fenestration of the front, east, elevation was largely preserved but new, large, west-facing widows were installed on both floors. |
| Space cooling strategy | Large thermal mass of original stone walls, MVHR summer bypass. Open the windows at night. |
| Daylighting strategy | Enlarged windows to sitting room and spare bedroom/study. Internal ground floor doors have frosted glass panels. |
| Ventilation strategy | Novus 300 MVHR with ISO frost protection. Touchscreen control in kitchen. |
| Airtightness strategy | Internal floor membrane sealed to existing internal wall plaster. Existing external cement render used as airtightness layer for walls. DA airtightness membrane over OSB on roof, sealed to walls with cement render. |
| Strategy for minimising thermal bridges | Some internal walls removed to reduce heat lost to ground. EWI extended 300 mm below internal floor level. Original chimney stack through roof removed. |
| Modelling strategy | PHPP |
| Insulation strategy | Floors excavated and insulated with 150 mm Ecotherm. 200 mm Plustherm graphited EPS EWI on the smoothed original cement render finish. Weatherproofed with K-rend system. Roof: 100 mm Ecotherm above airtightness membrane and 90 mm Knauf Earthwool insulation between rafters. |
| Other relevant retrofit strategies | Prior to purchase the property was identified as suitable for EnerPHit refurbishment because of its original external render finish (enabling EWI to be used), its box-like form, and absence of lossy protrusions such as dormer windows. It transpired that the original render finish could be used as the airtightness layer for the walls. Adopting a warm-roof strategy gave easy access to the MVHR in the loft for filter changes. |
| Contextual information | Although Rectory Cottage is located in a conservation area, the original external finish was a cement render over the stone walls. The nature of the external finish was therefore unchanged using EWI with a weatherproof render system. The original window openings of the front elevation were retained. |
Building services
| Occupancy | |
|---|---|
| Space heating | |
| Hot water | |
| Ventilation | |
| Controls | |
| Cooking | |
| Lighting | |
| Appliances | |
| Renewable energy generation system | |
| Strategy for minimising thermal bridges |
Building construction
| Storeys | 2 |
|---|---|
| Volume | 452.4m³ |
| Thermal fabric area | 466 m² |
| Roof description | |
| Roof U-value | 0.15 W/m² K |
| Walls description | |
| Walls U-value | 0.12 W/m² K |
| Party walls description | |
| Party walls U-value | - |
| Floor description | |
| Floor U-value | 0.14 W/m² K |
| Glazed doors description | |
| Glazed doors U-value | - - |
| Opaque doors description | |
| Opaque doors U-value | - - |
| Windows description | |
| Windows U-value | 0.75 W/m² K - |
| Windows energy transmittance (G-value) | - |
| Windows light transmittance | - |
| Rooflights description | |
| Rooflights light transmittance | - |
| Rooflights U-value | - |