End terrace IWI & SIPS replacement extension, Hereford
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as PDF The three storey (room in the roof) end victorian terrace, one of 3 terraced homes in a quiet street in Hereford was retrofitted in order to improve comfort and accessibility for an older couple, as well as to minimise running costs and greenhouse gas emissions. The property suffered from poor air quality, mould and required repair to the suspended floors. The single storey uninsulated single skin brickwork kitchen and bathroom out back was considered substandard and was replaced with structural insulated panels (SIPs) on metal ground screw foundations. The ceiling fo the first floor was treated as the retrofit boundary to avoid the costs of renewing the roof at this time. The adjoining two neighbours attic spaces were insulated as part of the works. A corn starch bound expanded perlite internal wall insulation board was trialled in the house and omnisense environmental condition sensors have been built into the construction in a joint project with Remmers UK & Green Building Store.
End terrace IWI & SIPS replacement extension, Hereford : 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 | - | 1000 kWh/yr | - |
|---|---|---|---|
| Natural gas use | - | 4662 kWh/yr | - |
| Oil use | - | - | - |
| LPG use | - | - | - |
| Wood use | - | - | - |
| Other Fuel | - | - | - |
| Pre-development | Forecast | Measured | |
| Primary energy requirement | - | 154 kWh/m².yr | - |
|---|---|---|---|
| Annual CO₂ emissions | - | 30 kg CO₂/m².yr | - |
| Annual space heat demand | - | 99 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 | 154 kWh/m².yr | - |
| Annual CO₂ emissions offset by renewable generation | 30 kg CO₂/m².yr | - |
Calculation and targets
| Whole house energy calculation method | PHPP |
|---|---|
| Other whole house calculation method | - |
| Energy target | AECB CarbonLite Retrofit targets |
| Other energy targets | referenced AECB carbonlite space heat demand targets - close correlation with those for this house type/form factor. |
| Forecast heating load | 33 W/m² demand |
Airtightness
| Date | Result | |
| Pre-development air permeability test | - | - |
|---|---|---|
| Final air permeability test | - | - |
Project description
| Stage | Occupied |
|---|---|
| Start date | 01 January 2019 |
| Occupation date | 20 December 2019 |
| Location | Hereford Herefordshire England |
| Build type | Mixed |
| Building sector | Private Residential |
| Property type | End Terrace |
| Construction type | Solid Brick |
| Other construction type | rendered brickwork, extension is timber clad (fire proofed) |
| Party wall construction | |
| Floor area | 50.9 m² |
| Floor area calculation method | Treated Floor Area (PHPP) |
| Building certification |
Project Team
| Organisation | |
|---|---|
| Project lead person | Andrew Simmonds |
| Landlord or Client | Mr & Mrs Simmonds |
| Architect | Simmonds.Mills |
| Mechanical & electrical consultant | |
| Energy consultant | |
| Structural engineer | BJSE |
| Quantity surveyor | |
| Consultant | Tim Martel for PHPP and embodied carbon calculations |
| Contractor | Alistair Dunbar |
Design strategies
| Planned occupancy | 2 people, currently intermittently. |
|---|---|
| Space heating strategy | retention of existing gas combi boiler and radiators. Move to a heat pump when affordable. |
| Water heating strategy | retention of existing gas combi boiler. Move to a heat pump when affordable. Area in (unheated) basement earmarked as potential plant space. |
| Fuel strategy | Until heat pump affordable the existing gas combi boiler was retained |
| Renewable energy strategy | limited roof space, currently no PV panels fitted. |
| Passive Solar strategy | terrace is east & west facing, limited opportunities to increase solar gain from the south. |
| Space cooling strategy | west facing glazing (bedroom window, living room window and glazed front door) is currently not shaded. In addition large full width folding doors on the east side are also unshaded. However PHPP shows overheating risk at 2%. If overheating occurs, shading features will be considered. |
| Daylighting strategy | increased glazing areas to kitchen and living room plus the use of a sunpipe in the kitchen have improved daylighting levels. |
| Ventilation strategy | whole house MEV unit in kitchen extracting from the kitchen and adjecent bathroom. This means no duct runs at all, and the exhaust in vertically up out through the flat roof of the kitchen extension. |
| Airtightness strategy | main house:walls - airtightness plane was the lime based levelling plaster applied to the brickwork behind the IWI board. In addition the board adehsive reduces air infiltration e.g. in areas where lime plaster was retained. floor - SIPs floor panels, joints taped and perimeter taped to walls. First floor joists used painted aerosana from timber to levelling plaster junctions.Ceilings in first floor, used grommets for cables, tape for misc. joints and painted on aerosana for awkward areas around josts/attic hatch. |
| Strategy for minimising thermal bridges | IWI meets insulated SIPs floor panels and meets first floor ceilings which are insulated between joists with cellulose insulation. Window reveals insulated. The project has no thermal bridges. Weak areas are the sunpipe and the MEV exhaust through the roof as well as the two retained uPVC 2g windows. |
| Modelling strategy | PHPP, use fo THERM and use of PHribbon for embodied carbon emissions. |
| Insulation strategy | IWI, plus structural insulated panels for the replacement extension. High performance foam in the SIPS due to very narrow site forcing poor form factor for the kitchen and dining extension, low thermal performance IWI for moisture management resons in the main house and attic spaces. |
| Other relevant retrofit strategies | minimising concrete for foundations through use of galvanised metal ground screw foundations. Use of off site SIPs panels manufacture to minimise noise and disturbance on site. Used to replace suspended ground floor throughout entire house and into new kitchen extension. Supported on and spanning between 2 no. steel beams through main house. |
| Contextual information | House is next to EnerPHit certified Grove Cottage |
Building services
| Occupancy | 2 adults (intermittently used, space heating & electricty use is estimated as if in full time use at 20C) |
|---|---|
| Space heating | as per design stage |
| Hot water | as per design stage |
| Ventilation | as per design stage |
| Controls | remote control thermostat for boiler |
| Cooking | induction hob, electric oven, microwave |
| Lighting | LEDs throughout |
| Appliances | fridge A rated (existing fridge retained) |
| Renewable energy generation system | none |
| Strategy for minimising thermal bridges | as per design stage |
Building construction
| Storeys | 3 |
|---|---|
| Volume | 133m³ |
| Thermal fabric area | 2415 m² |
| Roof description | tiled on bituminous felt on rafters, part lathe and plaster ceilings in slopes of attic room. Roof was not part of retrofit. Thermal plane is first floor ceiling: carpet, floorboards, joists (cellulose between) lather and plaster with gypsum skim. |
| Roof U-value | 0.29 W/m² K |
| Walls description | sitek, powerprotect board on levelling and adhesive layers, lime based plaster finish. external walls 80mm board, party wall 25mm |
| Walls U-value | 0.46 W/m² K |
| Party walls description | sitek board on old plaster on 100mm of brick, neighbour's plaster other side |
| Party walls U-value | 0.89 W/m² K |
| Floor description | 225mm thick SIPs panels, countrbattens, 18mm chipboard, floating cork flooring |
| Floor U-value | 0.10 W/m² K |
| Glazed doors description | lacuna 3g and Green Building Store Ultra 3g |
| Glazed doors U-value | 0.89 W/m² K installed |
| Opaque doors description | none |
| Opaque doors U-value | 0.93 W/m² K installed |
| Windows description | ultra for new, 2g for retained |
| Windows U-value | 0.86 W/m² K - |
| Windows energy transmittance (G-value) | - |
| Windows light transmittance | - |
| Rooflights description | |
| Rooflights light transmittance | - |
| Rooflights U-value | - |