Belvoir Cottage

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Belvoir Cottage has been designed as a modern version of a traditional Kentish cottage with dormer windows and catslide roof. It has, within the constraints of the LPA, been designed using low energy PH methodology meeting the PHPP criteria. The foundation system used was the first Isoquick PHI certified installation in the UK. A novel portal all timber I-beam construction method is used which reduces thermal bridging to a minimum. The majority of components used have PHI certification.
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Belvoir Cottage : 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 - 1000 kWh/yr 638 kWh/yr
Natural gas use- - -
Oil use- - -
LPG use- - -
Wood use- - -
Other Fuel - - -
Primary energy requirement - 21 kWh/m².yr 13 kWh/m².yr
Annual CO₂ emissions - 5 kg CO₂/m².yr 3 kg CO₂/m².yr
Annual space heat demand - 13 kWh/m².yr -

Renewable energy

Electricity generationForecastMeasured
Renewables Technology--
Other Renewables Tech--
Electricity consumed by generation --
Primary energy requirement
offset by renewable generation
21 kWh/m².yr 13 kWh/m².yr
Annual CO₂ emissions
offset by renewable generation
5 kg CO₂/m².yr 3 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 9 W/m² demand


Pre-development air permeability test17 February 20160.49m³/m².hr @ 50 Pascals
Final air permeability test03 October 20170.47m³/m².hr @ 50 Pascals

Project description

Start date26 July 2010
Occupation date03 April 2018
Location Ash, Canterbury Kent  England
Build typeNew build
Building sectorPrivate Residential
Property typeDetached
Construction typeOther
Other construction typeI-beam timber frame
Party wall construction
Floor area 119.8
Floor area calculation method Treated Floor Area (PHPP)
Building certification

Project Team

Project lead personPeter Starck
Landlord or ClientPeter Starck & Wendy Johnson
ArchitectPeter Starck & Wendy Johnson
Mechanical & electrical consultant
Energy consultant
Structural engineerSteve Green
Quantity surveyor

Design strategies

Planned occupancyTwo adults full time
Space heating strategyRequirement was calculated as 1.14kW at minus ten degrees celsius outside temperature. This will be provided by a Genvex Combi 185 compact unit, low level electric underfloor heating in the kitchen and electric towel rails in the bathrooms.
Water heating strategyProvided by Genvex Combi 185 compact unit. Hot water usage minimised by utilising aerating taps and showers.
Fuel strategyMains electricity supplemented by PV.
Renewable energy strategy
Passive Solar strategyWindow proportions optimised using PHPP.
Space cooling strategyNatural ventilation for most of the cooling season.
Daylighting strategy
Ventilation strategyComfort ventilation with heat recovery in winter. Opening windows in summer.
Airtightness strategy Icynene spray foam insulation in the walls and roof with expanding tape to window and door frames.
Strategy for minimising thermal bridges Continuous insulation layer maintained from insulated raft foundation to ridge.
Modelling strategyWhole house modelling was undertaken in PHPP.
Insulation strategyWalls and roof to achieve U value of 0.09 W/m2K. Foundations to achieve U value of 0.10 W/m2K. PHI certified triple glazed windows and doors.
Other relevant retrofit strategies
Contextual informationPassivHaus design has been carried out within the constraints imposed by the LPA.

Building services

OccupancyTwo adults full time.
Space heatingThis has been provided by an electric towel rail in each of the three bathrooms and electric UFH in the kitchen. This is supplemented with warm air from the EASHP in the Genvex Combi 185 LS.
Hot waterThis has been met using the EASHP in the Genvex Combi 185 LS without using the immersion.
VentilationThe MVHR in the Genvex Combi 185 LS has provided ventilation to the required level.
ControlsThe only control is the Optima 312 which fully controls the Genvex Combi 185 LS. This located in the hall.
CookingCooking has been carried out using an induction hob, electric fan oven and microwave oven.
LightingAll lighting is LED around 2700K.
AppliancesA+ rated fridge/freezer, washing machine and dishwasher.
Renewable energy generation systemSolar ready design. No installation has yet been undertaken.
Strategy for minimising thermal bridgesInsulated raft foundation with insulation upstands joining external wall insulation which joins external insulation on the roof.

Building construction

Storeys 2
Volume 306.2
Thermal fabric area 1974
Roof description 350mm I-beam with 350mm Icynene LDR50 insulation, 15mm OSB3 racking, 50mm high density rockwool batts, 50mm air gap with Nu-Lok porcelain tile finish.
Roof U-value 0.09 W/m² K
Walls description 350mm I-beam with 350mm Icynene LDR50 insulation, 15mm OSB3 racking, 50mm high density rockwool batts, 50mm air gap with cedar cladding.
Walls U-value 0.09 W/m² K
Party walls description
Party walls U-value -
Floor description Isoquick PHI certified 300mm insulation with 200mm concrete raft.
Floor U-value 0.10 W/m² K
Glazed doors description Internorm PassivHaus
Glazed doors U-value 0.86 W/m² K installed
Opaque doors description
Opaque doors U-value - -
Windows description Rehau PHI certified manufactured in the UK by Solent Glass Ltd.
Windows U-value 0.73 W/m² K installed
Windows energy transmittance (G-value) 50 %
Windows light transmittance 50%
Rooflights description Fakro
Rooflights light transmittance 32%
Rooflights U-value 0.90 W/m² K