IN DETAIL Building type: Detached 5-bedroom timber frame house. Gross internal area 400 sqm. Location: Harpenden, Hertfordshire Completion date: October 2017 Budget: Private Passive house certification: Certified Space heating demand (PHPP): 12.0 kWh/m2/yr
this spend was for hot water. He says: “All the [space] heating was really from solar gain, people, four cats and the stove. As well as heating the heat store (6kW), the stove gives some heat (2kW) to the room, and the general ventilation seemed to propagate this around the house nicely.” All wood used for the stove was left over from siteworks.
Weldano roof membrane, 15mm Smartply OSB, 300mm I-Beam timber joists at 400mm c/c fully insulated with Warmcel insulation (thermal conductivity at 0.038 W/m2K), ProClima Intello Plus vapour control layer, 100x45mm timber battens to form ceiling void, 12.5mm plasterboard, 3mm painted skim. U-value 0.130 W/m2K
Ground floor: 400mm KORE Floor EPS100 white insulation (EPS300 to perimeter) under 100mm reinforced concrete slab, 4mm concrete screed and 18mm timber floor finish. U-value: 0.092 W/m2K
Windows, external doors, patio doors: Internorm HF310 passive house certified timber-aluminium window. Average window U-value 0.83 Wm2K. Average g-value 0.45. Internorm HF310 Door, HS330 sliding door and AT410 front door.
Heat load (PHPP): 9 W/m2 Primary energy demand (non-renewable, PHPP): 45 kWh/m2/yr Primary energy renewable demand (PER, PHPP): 37 kWh/m2/yr Heat loss form factor (PHPP): 2.81 Overheating (PHPP): 2% Airtightness (at 50 Pascals): 0.51 ACH
Walls: 20mm sweet chestnut timber cladding externally, followed inside by 150mm rainscreen cavity formed with timber battens, Solitex Fronta WA monolithic wind tight breather membrane, 12mm Medite vent MDF sheathing panel, 400mm twin timber stud wall formed with 38x89mm studs at 400 c/c fulfilled with Warmcel insulation (thermal conductivity at 0.038 W/m2K), 12.5mm SmartPly ProPassiv board, 45x45mm battens to form service void, 12.5mm Plasterboard, 3mm painted skim. U-value: 0.107 W/m2K
Energy performance certificate (EPC): A (97) Measured energy consumption: In first 12 months, an estimated 2m3 of wood and 82m3 of gas (914kWh) consumed for space & water heating. Thermal bridging: MBC timber frame system with accredited detail Psi-values; average Psi-value produced by structural steel within superstructure: 0.068 W/mK; chimney Psi-value 0.370 W/mK; stove sporadic operation Psi-value 2.645 W/mK; SVP Psi-value 0.303 W/mK. Total Thermal Bridges account: for 2.7 kWh/m2 Energy bills (measured or estimated): During his first 12 months in the house, Danny Luhde Thompson paid £38 for 82m3 of gas, plus £94 in standing charges. However, from his monitoring he estimates that almost all of
Sarnafil G 410-18EL felt (1.8mm) externally fully bonded to 18mm plywood, followed underneath by 50x50mm ventilated timber battens and timber firrings fixed through to joists, Ampatop Protecta Plus roof membrane, 15mm Smartply OSB, 400mm I-Beam timber joists at 400mm c/c fully insulated with Warmcel insulation (thermal conductivity at 0.038 W/m2K), ProClima Intello Plus vapour control layer, 200x50mm timber battens to form ceiling void, 12.5mm plasterboard, 3mm painted skim. U-value: 0.096 W/m2K Terrace: 20mm external floor finish, followed underneath by plastic pedestal, Sarnafil protection sheet, Sarnafil G 410-18EL Felt (1.8mm) fully bonded to 18mm plywood, 95x50mm ventilated timber battens and timber firrings fixed through to joists, Solitex
Roof window: Lamilux FE Energysave. Passive House Institute certified. Overall U-value: 0.84 W/m2K Heating system: Rokossa IG2 RLU log boiler stove. 90 tube solar evacuated tube array with Resol differential controller. Worcester Greenstar 24Ri gas boiler (24kW), All supplying 500 litre Energystore Biosolar heat store which in turn supplies underfloor heating, towel rails to upstairs bathrooms, a duct heater in in the supply of fresh air upstairs. Heatstore also supplying domestic hot water Ventilation: Paul Novus 450 with summer bypass and electric defroster. Lindab ductwork. Roof window motorised, Lindab ductwork. Motorised roof window for extra ventilation. Water: F Line 7,500 litre tank collecting rainwater used for toilets and garden watering. External blinds: Roma Quadro 130 S Motorised External blind system. Reduction factor for temporary sun protection at 24%. Green materials: FSC certified sweet chestnut cladding, ash floor & ceiling, Warmcel cellulose insulation, EICO paints, timber frame structure.
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