Whole house retrofit of a typical Victorian solid wall detached property in Brighton

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The aim is for a realistic, replicable and robust whole house solution to retrofitting solid wall Victorian housing to dramatically reduce carbon loads through space and water heating, and electrical consumption. The project will use established technologies that when combined offer the best carbon return per spent and when used together are more that the sum of their parts. The project will focus on upgrading the thermal envelope of all the external elements walls / floors / roof / glazing to achieve the optimum balance of u-values and air tightness in the context of existing building. Energy efficient services for space and water heating and appliances are the other elements of our whole house.

Retrofit for the future ZA467S
Images Graphs Figures Description Strategies Building

Whole house retrofit of a typical Victorian solid wall detached property in Brighton : Project images

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CO2 emissionsPrimary energy requirement
Energy target
Retrofit for the Future

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 4061 kWh/yr 3162 kWh/yr 3915 kWh/yr
Natural gas use80054 kWh/yr 10647 kWh/yr 8407 kWh/yr
Oil use- - -
LPG use- - -
Wood use- - -
Other Fuel - - -
Primary energy requirement 577 kWh/m².yr 114 kWh/m².yr 110 kWh/m².yr
Annual CO₂ emissions 107 kg CO₂/m².yr 23 kg CO₂/m².yr 23 kg CO₂/m².yr
Annual space heat demand - 40 kWh/m².yr -

Renewable energy

Electricity generationForecastMeasured
Renewables Technology--
Other Renewables Tech--
Electricity consumed by generation --
Primary energy requirement
offset by renewable generation
114 kWh/m².yr 110 kWh/m².yr
Annual CO₂ emissions
offset by renewable generation
23 kg CO₂/m².yr 23 kg CO₂/m².yr

Calculation and targets

Whole house energy calculation method SAP
Other whole house calculation method-
Energy target Retrofit for the Future
Other energy targets-
Forecast heating load 7850 W/m² demand


Pre-development air permeability test-9.76m³/m².hr @ 50 Pascals
Final air permeability test-3m³/m².hr @ 50 Pascals

Project description

StageUnder construction
Start date01 March 2010
Occupation date30 September 2010
Location Brighton East Sussex  England
Build typeRefurbishment
Building sectorPublic Residential
Property typeDetached
Construction typeSolid Brick
Other construction type215mm brick
Party wall construction
Floor area 177
Floor area calculation method Treated Floor Area (PHPP)
Building certification

Project Team

OrganisationEarthwise Construction Ltd
Project lead personEarthwise Construction Ltd
Landlord or ClientTwo Piers Housing Co-Operative
ArchitectBBM Sustainable Design Ltd
Mechanical & electrical consultant Robinson Associates
Energy consultant
Structural engineer
Quantity surveyor
ConsultantNBT Consult, Roger Case Design & Management, University of Brighton
ContractorEarthwise Construction Ltd

Design strategies

Planned occupancySix bedrooms, some work at home during the week.
Space heating strategyHeating from mains gas condensing boiler feeding radiators; Heat recovered from exhaust air using very efficient MHVR system.
Water heating strategySolar hot water from evacuated tube system; Gas condensing boiler back up.
Fuel strategyMains Gas; Mains electricity.
Renewable energy strategyN/a
Passive Solar strategy
Space cooling strategyNatural ventilation for most of the cooling season; Daytime use of MVHR with night purging during heat waves.
Daylighting strategyAll kitchens achieve a minimum average daylight factor of at least 2%; All living rooms, dining rooms and studies achieve average daylight factor of at least 1.5%.
Ventilation strategyComfort ventilation with heat recovery (winter); Openable windows (summer); MVHR and window opening will be monitored.
Airtightness strategy External masonry to have parge coat to provide continuous air barrier with membrane all apertures taped to ensure airtightness at critical junctions; Roof structure sealed to inside face of external masonry wall to create continuous layer; Airtight layer to be sealed to insulation layer in loft; Solid concrete ground floor slab to be taped at junctions.
Strategy for minimising thermal bridges Continuous insulation maintained throughout where possible; Returns of 1m insulation where internal/external insulation of front elevation occurs; Geometric thermal bridges minimised; Thermal bridging analysis undertaken for all primary junction interfaces, in order to assist with value engineering and where possible design out / reduce mechanical fixing and where necessary low-thermal conductive fixings used; Junctions assessed include: ground floor junction, external corner, eaves, verge, window jamb, head and sill, door jamb, head and threshold.
Modelling strategyWhole house modeling was undertaken in SAP and PHPP.
Insulation strategyApplication of external insulation to solid brick walls on north, south, and east elevations (to achieve U-value of 0.15 W/m2K); Application of internal render on street facing west elevation (to achieve U-value of 0.15 W/m2K); Insulated floating floor over existing solid cement ground slab (to achieve U-value of 0.14 W/m2K); Removal of existing mineral fibre loft insulation to create service zone, joists over boarded with insulation boards and insulation boards at rafter line (to achieve U-value of 0.10 W/m2K).
Other relevant retrofit strategiesWe are planning to carry out our package of retrofit measures with tenants remaining in the dwelling during the proposed works; We intend to demonstrate our approach can be undertaken with minimal disruption to the tenants and with no associated temporary re-housing costs.
Contextual informationEnergy band F - current SAP energy rating of 33; Large, but compact building form with simple external architectural detailing; Few and limited external openings, bay windows on front elevation; HMO - no hierarchy of internal spaces, bedrooms on ground and first floor; Six bedrooms, several bathrooms and a large open plan kitchen and living room, with doubling up of appliances; Existing boiler system is 'heavy', unresponsive, poorly maintained and is over 25 years old; Co-operative ownership & management by residents who are RSL; Currently has high levels of multiple occupancy with vastly differing lifestyles and requires flexibility in operation; High levels of occupancy with high electrical and water requirement issues.

Building services

Space heatingNULL
Hot waterNULL
Renewable energy generation systemNULL
Strategy for minimising thermal bridgesNULL

Building construction

Volume -
Thermal fabric area -
Roof description NULL
Roof U-value 0.00 W/m² K
Walls description NULL
Walls U-value 0.00 W/m² K
Party walls description NULL
Party walls U-value 0.00 W/m² K
Floor description NULL
Floor U-value 0.00 W/m² K
Glazed doors description NULL
Glazed doors U-value 0.00 W/m² K -
Opaque doors description NULL
Opaque doors U-value 0.00 W/m² K -
Windows description NULL
Windows U-value 0.00 W/m² K -
Windows energy transmittance (G-value) -
Windows light transmittance -
Rooflights description NULL
Rooflights light transmittance -
Rooflights U-value 0.00 W/m² K