| Planned occupancy | Family of four. Two adults and two children. |
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| Space heating strategy | Natural gas system boiler coupled to a 145 litre DHW hot water cylinder. No secondary heating. The MVHR (mechanical ventilation heat recovery) system will recover the heat contained in the stale exhaust air via a heat exchanger, pre-heating the incoming fresh air. |
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| Water heating strategy | Space heating boiler as above, coupled to a 145 litre hot water cylinder. |
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| Fuel strategy | Main gas. Mains electricity. |
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| Renewable energy strategy | 1.72 kWp of roof mounted PV array. |
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| Passive Solar strategy | The rear south facing windows are small and shaded by adjoining houses and yard walls. PHPP predicts available solar gains of 2.8kWh/m2/year. Solar gain will be maximised in the retrofit by using Passivhaus windows with narrow frame widths to provide maxiumum glazed area. |
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| Space cooling strategy | Opening windows to provide passive cross ventilation will cool in the day and purge the house at night. This will allow the option of switching off MVHR in the summer, reducing primary energy (PE) demand. Internal solar blinds and external roll out solar shading will control the solar gain in the summer season if required. |
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| Daylighting strategy | Daylighting factors currently pre retrofit, front room 1.8, dining room 1.2, kitchen 1.6. The window openings within the walls of the house are fixed dimentionally. The windows to the south facing rear of the house are surrounded by the high walls of an enclosed yard and adjoining houses. The glazed area of each retrofitted Passivhaus window will be maximised by the use of narrow frames widths increasing the glazing area from what it is currently, improving daylighting with a higher daylight factor. |
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| Ventilation strategy | A mechanical ventilation and heat recovery (MVHR) system will be operating throughout the heating season. The MVHR summer bypass option will draw fresh outside air from the cooler shaded north side of house and supply it into the house in the summer. Alternatively, the MVHR can be turned off in the summer to reduce PE demand and the house cooled with cross ventilation by opening windows. |
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| Airtightness strategy | Masonary walls parged down to the floor slab and between floor joists. Floors taped to the walls to create an airtight seal. Internal insulation plywood substructure cut to encompass floor/ceiling joists between floors with taped joints to provide an air tight seal. Airtight membrane/vapour barrier mounted inside roof structure, bonded to parged masonary walls. Services (pipes,cables, ducting, etc) penetrations through airtight barrier sealed with gaskets, tape or airtight sealant and windows sealed to wall/airtight membrane. Socket outlet/switch boxes. ceiling roses, etc, sealed for airtightness. |
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| Strategy for minimising thermal bridges | Thermal bridging analysis conducted on each potential thermal bridge using THERM software. Replacement floor slab on top phenolic insulation will have edge insulation to minimise the thermal bridge to the adjoining walls. Flanking insulation will be installed on the internal party walls to minimise thermal bridging and prevent condensation at the junction of the party wall and external wall. Aerocell and closed cell foam insulation inserted around the face and sides of window/door frames to minimise the thermal bridge with the masonary. |
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| Modelling strategy | Whole house modelling using PHPP. The PV output was calculated manually using a PV yield for Northern Ireland of 850kWh/year per kWp. The 8 module 1.720kWp array has a predicted annual yield of 1.720kWp x 850 = 1.462kWh. |
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| Insulation strategy | Combination of aerogel and phenolic internal insulation installed on the external walls to achieve a U-value of 0.15W/m2K. Replacement of existing concrete floor (which has no insulation) with a concrete slab over phenolic insulation to achieve a U-value of 0.10 W/m2K. Edge insulation to minimise thermal bridging between floor slab and walls. Removal and replacement of existing attic bedroom ceiling to allow for the installation for a combination of different types of insulation to achieve a U-value of 0.10 W/m2K. Passivhaus windows with a U-value of 0.8 will be installed. |
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| Other relevant retrofit strategies | Due to health and safety issues, the extent of and the length of time required to complete this initial retrofit, the tenants will be accommodated in an alternative unnoccupied spare house within the existing HA stock. For any future small scale retrofit roll out, it envisaged a spare house will be available to keep alternative (hotel) accommodation costs low. To minimise traffic disruption in narrow terraced streets and reduce the transport carbon footprint, it is proposed that all the retrofit components are containerised offsite. The loaded10 foot (the width of a terraced house) container, can then be placed in the road directly outside the house. |
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| Contextual information | 1) Standby killer electrical circuits installed in each room to enable appliances with a standby mode plugged into green socket outlets, to be switched off from one central switch. 2) A bath/shower drain water heat recovery/heat store system will pre-heat incoming mains water. This potential saving has not been entered into PHPP. The performance will be measured by installing heat meters on the inlet and outlet of the unit. |
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