The Den, Anstey, Dorset

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New timber framed detached passivhaus
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The Den, Anstey, Dorset : 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

Renewable electricity generation This project has used the contributions from renewable electricity generation equipment to either meet the Retrofit for the Future target or otherwise reduce the Primary energy requirement and CO₂ emissions associated with the project.

Measured data from renewable generation is not yet available.

Fuel use

Electricity use - - 372 kWh/yr
Natural gas use- - -
Oil use- - -
LPG use- - -
Wood use- - -
Other Fuel - - -
Primary energy requirement - - 6 kWh/m².yr
Annual CO₂ emissions - - 1 kg CO₂/m².yr
Annual space heat demand - - 12 kWh/m².yr

Renewable energy

Electricity generationForecastMeasured
PV array-2518 kWh/yr
Other Renewables Tech--
Electricity consumed by generation -1259 kWh/yr
Primary energy requirement
offset by renewable generation
--14 kWh/m².yr
Annual CO₂ emissions
offset by renewable generation
--4 kg CO₂/m².yr

Calculation and targets

Whole house energy calculation method
Other whole house calculation method-
Energy target PassivHaus
Other energy targets-
Forecast heating load -


Pre-development air permeability test--
Final air permeability test07 November 20130.585m³/m².hr @ 50 Pascals

Project description

Start date06 January 2013
Occupation date06 September 2013
Location Anstey Dorset  England
Build typeNew build
Building sectorPrivate Residential
Property typeDetached
Construction typeSoftwood frame
Other construction type
Party wall construction
Floor area 158.6
Floor area calculation method Treated Floor Area (PHPP)
Building certification

Project Team

OrganisationConker Conservation Ltd
Project lead person
Landlord or ClientD Merrigan
ArchitectConker Conservation Ltd
Mechanical & electrical consultant Green Building Store
Energy consultantConker Conservation Ltd
Structural engineer
Quantity surveyor
ConsultantConker Conservation Ltd
ContractorPrincipal Contracts Ltd

Design strategies

Planned occupancy
Space heating strategy
Water heating strategy
Fuel strategy
Renewable energy strategy
Passive Solar strategy
Space cooling strategy
Daylighting strategy
Ventilation strategy
Airtightness strategy
Strategy for minimising thermal bridges
Modelling strategy
Insulation strategy
Other relevant retrofit strategies
Contextual information

Building services

OccupancyFamily house 3 to 4 persons.Initially will be used a second home, but will revert to main family home within 2 years.
Space heatingWood stove only, located in the first floor living area which is double height. Ability to install a post heater in to MVHR if required in the future.
Hot waterDirect electric cylinder, but connected to PV array via Immersun controller.
VentilationPaul Novus 300 MVHR system, serving all rooms plus large built in cupboards and loft.
ControlsManual controls on air inlet of wood stove.
LightingLED down lights and wall lights in most rooms.
Renewable energy generation systemFakro flat solar thermal collectors, 114 x 140, 114 x 206cm, 3.0kW, only recently MCS accredited.Fakro PV panels 2.42Kw peak. All panels match the Fakro triple glazed roof lights.
Strategy for minimising thermal bridgesCareful analysis of timber frame to reduce timber fraction. External layer of wood fibre insulation overlaps all windows and doors.

Building construction

Storeys 3
Volume 661
Thermal fabric area 461
Roof description 300mm timber I joists, over clad with 52mm wood fibre, void filled with cellulose fibre, internal sheeting of OSB.
Roof U-value 0.11 W/m² K
Walls description 300mm timber I joists, over clad with 52mm wood fibre, void filled with cellulose fibre, internal sheeting of OSB, service void and Fermacell internal boarding.
Walls U-value 0.11 W/m² K
Party walls description
Party walls U-value -
Floor description Polished concrete floor 100mm thick, laid on to 250mm XPS in two layers, on blinding and hardcore. This minimises the amount of concrete needed, but requires protection throughout the build.
Floor U-value 0.12 W/m² K
Glazed doors description Living Wood Windows triple glazed with aluminium cladding. Most units are simple side hung, but to west elevation lift and slide inward tilt units used.
Glazed doors U-value 0.71 W/m² K uninstalled
Opaque doors description None
Opaque doors U-value - -
Windows description Living Wood Window triple glazed with aluminium cladding, tilt and turn.
Windows U-value 0.70 W/m² K uninstalled
Windows energy transmittance (G-value) 0.498 %
Windows light transmittance 70.42%
Rooflights description Fakro FTT Thermo triple glazed centre pivot with insulated AHV Thermo flashing and airtight collar.
Rooflights light transmittance 70%
Rooflights U-value 0.74 W/m² K

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