Seldom Seen

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Seldom Seen was completed in 2018.A timber construction Passive House designed around a traditional oak frame, the house was designed to be sympathetic to its rural setting; a small village in the North Wessex Downs AONB.The house is also designed to meet the needs of a severely disabled family member; including wider doors/corridors, integrated lift, specialist bath, hoists and changing table.
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Seldom Seen : Project images

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CO2 emissionsPrimary energy requirement
Energy target

Energy and fuel use

Fuel use by type
Primary energy requirement
CO2 emissions

Measured data from renewable generation is not yet available.

Fuel use

Electricity use - - 5078 kWh/yr
Natural gas use- - -
Oil use- - -
LPG use- - -
Wood use- - -
Other Fuel - - -
Primary energy requirement - - 52 kWh/m².yr
Annual CO₂ emissions - - 12 kg CO₂/m².yr
Annual space heat demand - 11 kWh/m².yr -

Renewable energy

Electricity generationForecastMeasured
Renewables Technology--
Other Renewables Tech--
Electricity consumed by generation --
Primary energy requirement
offset by renewable generation
-52 kWh/m².yr
Annual CO₂ emissions
offset by renewable generation
-12 kg CO₂/m².yr

Calculation and targets

Whole house energy calculation method PHPP
Other whole house calculation method-
Energy target PassivHaus
Other energy targets-
Forecast heating load 8 W/m² demand


Pre-development air permeability test--
Final air permeability test30 January 20180.48m³/m².hr @ 50 Pascals

Project description

Start date01 May 2017
Occupation date17 January 2018
Location Devizes Wiltshire  England
Build typeNew build
Building sectorPrivate Residential
Property typeDetached
Construction typeOak frame
Other construction typeTimber clad (oak)
Party wall construction
Floor area 245
Floor area calculation method Treated Floor Area (PHPP)
Building certification  Passivhaus certified building Passivhaus certified building

Project Team

OrganisationErigo Ltd
Project lead personRebecca Thursby
Landlord or Client
ArchitectHill Design
Mechanical & electrical consultant Erigo Ltd / Current Electrical Solutions
Energy consultant
Structural engineerClegg Associates
Quantity surveyorErigo Ltd

Design strategies

Planned occupancyFamily of four; one disabled child, with carer when parents are out at work.
Space heating strategyUnder floor heating as back-up (not used)
Water heating strategyGround source heat pump with electric boiler
Fuel strategyMains electricity
Renewable energy strategy
Passive Solar strategyMost windows facing due south, with remainder on west and east elevations. Window proportions optimised using PHPP.
Space cooling strategyDaytime use of MVHR with night purging during heat waves.
Daylighting strategy
Ventilation strategyOpenable windows (only done at night time during the summer)
Airtightness strategy Timber frame in-filled with Icyenene sprayfoam insulation (039) 228mm, with pro-passive board on interior, then plasterboard. Medite vent on the exterior of the spray foam (and then Tyvek wrap and timber-clad).
Strategy for minimising thermal bridges Thermal bridging analysis undertaken for all primary junctions interfaces. Continuous insulation maintained throughout. Geometric thermal bridges minimised. Junctions assessed include: Ground floor junction, external corner, eaves, verge, window jamb, head and sill, door jamb, head and threshold.
Modelling strategy
Insulation strategyApplication of Icyenene sprayfoam insulation (039) 228mm to external walls and roof to achieve U-value of 0.124 W/(m2K)
Other relevant retrofit strategies
Contextual informationThe primary purpose of the house was to enable better care of a severely disabled child. In the basic design, this meant a large open ground floor area (for wheelchair access) as well as space for equipment (sleeping, medical & bathing), wider corridors and doors, and a disabled lift.It also meant accommodating extra loads on the floors, walls and ceilings from ceiling hoists, a changing table and a specialist disabled bath.

Building services

OccupancyFamily of four (plus two large dogs); one of the family is a disabled child who remains at home (with carer) whilst parents go to work.
Space heatingUnder floor heating and ethanol fire (neither required last winter)
Hot waterGround source heat pump and electric boiler
VentilationPaul, Novus 300. Balanced PH ventilation with HREffective heat recovery efficiency 90.1%
ControlsTemp - feedback loop on underfloor heating (if switched on)MVHR - three settings
CookingInduction hob and double oven (electric)
Lighting100% LED lighting
AppliancesA++ fridge freezer and A+ washing machine & dishwasher
Renewable energy generation systemNot included in design, to fit in better to rural area.
Strategy for minimising thermal bridges

Building construction

Storeys 2
Volume -
Thermal fabric area -
Roof description Timber frame, in-filled with Icyenene, sprayfoam insulation (039) 228mm, with pro-passive board on interior (then plasterboard) and medite vent on the exterior (then roof shield and tiles).
Roof U-value 0.13 W/m² K
Walls description Timber frame, in-filled with Icyenene, sprayfoam insulation (039) 228mm, with pro-passive board on interior and then plasterboard. External to sprayfoam is medite vent board, then Tyvek wrap and timber-clad (oak).
Walls U-value 0.12 W/m² K
Party walls description
Party walls U-value -
Floor description Insulated slab (Isoquick insulated raft) 200mm
Floor U-value 0.13 W/m² K
Glazed doors description Internorm triple-glazed sliding door
Glazed doors U-value 0.98 W/m² K installed
Opaque doors description 2 x external doors, both Internorm, one west-facing, one south-facing
Opaque doors U-value 0.73 W/m² K installed
Windows description Internorm triple-glazed 3N2-IL
Windows U-value 0.89 W/m² K installed
Windows energy transmittance (G-value) 50 %
Windows light transmittance -
Rooflights description Fakro quadruple glazed.U value included in calculation for 'Windows' (above)
Rooflights light transmittance -
Rooflights U-value -

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