Retrofit of detached 1990s house in Brinscall (currently in progress)
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as PDF This was a renovation project of a cavity-walled house built in 1990, located in Brinscall, Lancashire. The work includes both energy efficiency retrofit measures (e.g. insulation, MVHR) in tandem with some other work as part of the renovation (e.g. rejigging the heating system). The energy efficiency measures revolve largely around insulation, airtightness and ventilation.
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Fuel use
| Pre-development | Forecast | Measured | |
| Electricity use | 4247 kWh/yr | 1757 kWh/yr | - |
|---|---|---|---|
| Natural gas use | 19044 kWh/yr | 12100 kWh/yr | - |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | 269 kWh/m².yr | 152 kWh/m².yr | - |
|---|---|---|---|
| Annual CO₂ emissions | 53 kg CO₂/m².yr | 29 kg CO₂/m².yr | - |
| Annual space heat demand | 200 kWh/m².yr | 53.9 kWh/m².yr | - |
Renewable energy
| Electricity generation | Forecast | Measured |
|---|---|---|
| Solar thermal | 2236 kWh/yr | - |
| Solar PV | 1727 kWh/yr | - |
| Electricity consumed by generation | - | - |
| Primary energy requirement offset by renewable generation | 70 kWh/m².yr | - |
| Annual CO₂ emissions offset by renewable generation | 10 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 | 20 W/m² demand |
Airtightness
| Date | Result | |
| Pre-development air permeability test | 16 May 2016 | 9.53m³/m².hr @ 50 Pascals |
|---|---|---|
| Final air permeability test | - | - |
Project description
| Stage | Under construction |
|---|---|
| Start date | 14 August 2016 |
| Occupation date | |
| Location | Brinscall Lancashire England |
| Build type | Refurbishment |
| Building sector | Private Residential |
| Property type | Detached |
| Construction type | Masonry Cavity |
| Other construction type | 70mm cavity with mineral wool |
| Party wall construction | |
| Floor area | 120.75 m² |
| Floor area calculation method | Treated Floor Area (PHPP) |
| Building certification |
Project Team
| Organisation | |
|---|---|
| Project lead person | John Holland |
| Landlord or Client | John Holland |
| Architect | |
| Mechanical & electrical consultant | |
| Energy consultant | Eric Fewster, ColdProof |
| Structural engineer | |
| Quantity surveyor | |
| Consultant | Eco Heat & Power Ltd |
| Contractor | None (DIY) |
Design strategies
| Planned occupancy | Two people living in the house. |
|---|---|
| Space heating strategy | Heating to be about 85% from mains gas-fired boiler feeding radiators; 15% to come from wood-burning stove; heat recovered from whole house ventilation exhaust; contribution from solar thermal DHW system. |
| Water heating strategy | Water heated using Apricus solar thermal panels and heat topped up by gas. |
| Fuel strategy | Mains gas and wood logs; Mains electricity. |
| Renewable energy strategy | 12 existing solar PV panels. |
| Passive Solar strategy | |
| Space cooling strategy | |
| Daylighting strategy | |
| Ventilation strategy | MVHR unit to be installed, openable windows for summer. |
| Airtightness strategy | Airtightness to be achieved using attention to detail at all parts of renovation process. 3 fan tests planned, breathable membrane to be used in front of internal insulation and across first floor ceilings (including passing across top of stud walls). |
| Strategy for minimising thermal bridges | Thermal bridge modelling to be done on all junctions to reduce heat loss as much as practically possible. |
| Modelling strategy | Whole house modelling undertaken in PHPP for both pre- and post-retrofit scenarios. |
| Insulation strategy | Wood fibre boards to be fixed internally direct onto all external-facing walls (no timber studwork needed). Existing insulated solid floor to remain as is, existing suspended floor to be converted to insulated solid floor. Mineral wool insulation for the loft space. |
| Other relevant retrofit strategies | |
| Contextual information | This project management and actual DIY work is being carried out by the client directly, with some help as and when needed from myself as energy consultant. |
Building services
| Occupancy | Two people living in the house. |
|---|---|
| Space heating | Heating to be about 85% from mains gas-fired boiler feeding radiators; 15% to come from wood-burning stove; heat recovered from whole house ventilation exhaust; contribution from solar thermal DHW system. |
| Hot water | Water heated using Apricus solar thermal panels and heat topped up by gas, stored in 277 litre storage cylinder. |
| Ventilation | Paul Novus 300 MVHR unit with 82.2% installed efficiency (according to PHPP). Metal ducting. |
| Controls | Digital controls for MVHR. |
| Cooking | Gas oven/hob. |
| Lighting | 100% compact fluorescents or LEDs |
| Appliances | A-rated fridge/freezer unit, microwave and washing machine. |
| Renewable energy generation system | Existing solar PV & thermal panels to remain unchanged. |
| Strategy for minimising thermal bridges | Thermal bridge modelling was done on all junctions in order to reduce psi-value as close to zero as possible. There were two problematic junctions - solid partition wall to solid floor, and solid partition wall to external facing walls. In both cases to effectively reduce the psi-value would entail replacing brickwork, which wasn't an option in this case, so these were left as is, as a compromise. Other junctions were either negative or not far above zero. Junctions requiring additional materials/work were:- One junction between partition wall and two types of solid floor, where a 20cm wide strip of Spacetherm-P (10mm Spacetherm, 9.5mm plasterboard) helped nudge the psi-value in the right direction.- Front door threshold, where the new door is installed on compac foam blockwork- Utility door threshold where existing cavity under door and near threshold was to be filled with insulation. |
Building construction
| Storeys | 2 |
|---|---|
| Volume | 315m³ |
| Thermal fabric area | 419 m² |
| Roof description | 100mm mineral wool between joists, overlaid with 200mm sheeps wool |
| Roof U-value | 0.13 W/m² K |
| Walls description | Main cavity wall is brick 102.5mm, 70mm cavity with blown mineral wool, internal concrete block 120mm, followed by 140mm mineral wool and service zone.There is also a single skin block wall between house and garage, with 15mm existing EPS. This wall to have 140mm wood fibre added, probably on the garage side.The utility room to garage had to be rebuilt, and consists of two layers of blockwork sandwiching 80mm PIR, with another 75mm PIR and service zone on the internal side. |
| Walls U-value | 0.17 W/m² K |
| Party walls description | |
| Party walls U-value | - |
| Floor description | Most of the existing solid floor to remain unchanged - it is already insulated with 25mm EPS under floorboards. Current suspended floor in one room to be changed to well insulated solid floor with 145mm EPS below chipboard and floor boards. |
| Floor U-value | 0.77 W/m² K |
| Glazed doors description | Green Building Store existing patio doors. |
| Glazed doors U-value | 1.22 W/m² K installed |
| Opaque doors description | Green Building Store existing utility door and new front door. |
| Opaque doors U-value | 1.19 W/m² K installed |
| Windows description | Green Building Store Performance triple glazed windows (4mm/16mm argon/4mm/16 argon/4mm). |
| Windows U-value | 1.20 W/m² K - |
| Windows energy transmittance (G-value) | 53 % |
| Windows light transmittance | - |
| Rooflights description | |
| Rooflights light transmittance | - |
| Rooflights U-value | - |