Hutchcomb EnerPHit Plus
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as PDF This 1930s solid-brick semi-detached house in Oxford has been transformed to achieve maximum internal comfort and energy efficiency. With a deep green retrofit upgrade, this house is among one of the first EnerPHit Plus projects in the UK, certified in December 2020. Despite high groundwater, a concrete floor was avoided with a warm raft timber construction. With PV and battery, 60-70% of generation is expected to be exported, displacing fossil fuels in the grid. CO2 embodied in the build is expected to be offset within five years.
Hutchcomb EnerPHit Plus : 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 | - | - | 24 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 | |
|---|---|
| Other whole house calculation method | - |
| Energy target | EnerPHit |
| Other energy targets | - |
| Forecast heating load | - |
Airtightness
| Date | Result | |
| Pre-development air permeability test | - | - |
|---|---|---|
| Final air permeability test | - | 0.7m³/m².hr @ 50 Pascals |
Project description
| Stage | Occupied |
|---|---|
| Start date | |
| Occupation date | |
| Location | Oxford Oxfordshire England |
| Build type | Refurbishment |
| Building sector | Private Residential |
| Property type | Semi-Detached |
| Construction type | Masonry Cavity |
| Other construction type | |
| Party wall construction | |
| Floor area | 79 m² |
| Floor area calculation method | Treated Floor Area (PHPP) |
| Building certification |  Passivhaus certified building |
Project Team
| Organisation | |
|---|---|
| Project lead person | |
| Landlord or Client | Private |
| Architect | Alan Budden, Eco Design Consultants |
| Mechanical & electrical consultant | Green Building Store (MVHR) |
| Energy consultant | Mike Roe, Warm Company Ltd |
| Structural engineer | |
| Quantity surveyor | |
| Consultant | Laurence Michaelis |
| Contractor | Alex McCarthy, AMC Build |
Design strategies
| Planned occupancy | |
|---|---|
| Space heating strategy | Air to air heat pump, Mitsubishi Heavy Industries SRK20ZSX-W. |
| Water heating strategy | Point of use tankless electric water heaters. |
| Fuel strategy | |
| Renewable energy strategy | |
| Passive Solar strategy | |
| Space cooling strategy | |
| Daylighting strategy | |
| Ventilation strategy | Paul, Focus 200Balanced ventilation with heat recovery.0.63ac/h, effective heat recovery 87.5% |
| Airtightness strategy | |
| Strategy for minimising thermal bridges | |
| Modelling strategy | |
| Insulation strategy | |
| Other relevant retrofit strategies | |
| Contextual information |
Building services
| Occupancy | |
|---|---|
| Space heating | |
| Hot water | Point of use tankless electric water heaters. |
| Ventilation | Paul, Focus 200Balanced ventilation with heat recovery.0.63ac/h, effective heat recovery 87.5% |
| Controls | |
| Cooking | |
| Lighting | |
| Appliances | |
| Renewable energy generation system | |
| Strategy for minimising thermal bridges |
Building construction
| Storeys | 2 |
|---|---|
| Volume | 79m³ |
| Thermal fabric area | - |
| Roof description | Original roof of house: loft has been closed off, with airtight membrane below the joists, and filled with 600mm Knauf Dritherm 32. U-value 0.056. Roof of extension: Above rafters: 140mm phenolic foam fixed with battens and tiled. 120mm rafters filled with Knauf Dritherm 32. Airtight membrane below rafters. Service void constructed of 89mm timber filled with Knauf Dritherm 32. U-value 0.086 |
| Roof U-value | 0.07 W/m² K |
| Walls description | Several types:1. Solid brick with 200mm phenolic EWI: 0.0942. Solid brick with 120mm woodfibre IWI and 150mm phenolic EWI: 0.0923. Blockwork with insulated cavity and 200mm phenolic EWI: 0.0874. Single skin of blockwork internally insulated with 50mm mineral wool, 140mm phenolic foam, and 89mm studwork with mineral wool: 0.090. |
| Walls U-value | 0.09 W/m² K |
| Party walls description | |
| Party walls U-value | - |
| Floor description | Innovative design with joists fixed to withstand upward forces due to buoyancy of insulation in high rainfall episodes when groundwater is near surface.Build-up from the bottom up:150mm hardcore50mm sand bindingDPM225mm PIR insulation18mm OSBAirtight membrane150mm joists with packers to rest firmly on substructure, insulated with Knauf Dritherm 32T&G pine floorboards. |
| Floor U-value | 0.07 W/m² K |
| Glazed doors description | Three Green Building Store Ultra doorsFront and side doors are wood panel with a small glass pane. Rear door is fully glazed. |
| Glazed doors U-value | 0.99 W/m² K - |
| Opaque doors description | |
| Opaque doors U-value | - - |
| Windows description | Triple glazing, 4.E-18-4-18-4.E Argon, E=Planitherm XN |
| Windows U-value | 0.53 W/m² K - |
| Windows energy transmittance (G-value) | 54 % |
| Windows light transmittance | - |
| Rooflights description | |
| Rooflights light transmittance | - |
| Rooflights U-value | - |