Clapham Retrofit

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This 4-storey semi-detached Grade II listed Victorian townhouse has been eco-retrofitted to a high standard of airtightness and thermal performance. The 170-year old, solid brick building has been internally retrofitted with over 9 types of insulation material, each a bespoke solution to localised performance requirements respecting the historic significance of the existing fabric. The existing sash windows and doors have been upgraded through the installation of double-glazed secondary glazing. High performance insulation materials together with careful airtightness and thermal bridge detailing have resulted in a historic building that is both highly energy efficient and more comfortable to live in.
Images Graphs Figures Description Strategies Building

Clapham Retrofit : Project images

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Arboreal_Living_Room.jpg
051_Back_Garden.jpg
Arboreal_Street_View.jpg
051_Hallway.jpg
2nd_floor_bathroom.jpg
051_Stair_Window.jpg
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Arboreal_Rear_Elevation.jpg
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CO2 emissionsPrimary energy requirement
Energy target
AECB Silver

Energy and fuel use

Fuel use by type
Primary energy requirement
CO2 emissions
Renewables

Measured data from renewable generation is not yet available.

Fuel use

 Pre-developmentForecastMeasured
Electricity use - 3046 kWh/yr -
Natural gas use- 10837 kWh/yr 9171 kWh/yr
Oil use- - -
LPG use- - -
Wood use- - -
Other Fuel - - -
 Pre-developmentForecastMeasured
Primary energy requirement - 118 kWh/m².yr 62 kWh/m².yr
Annual CO₂ emissions - 24 kg CO₂/m².yr 11 kg CO₂/m².yr
Annual space heat demand 180 kWh/m².yr 40 kWh/m².yr 40 kWh/m².yr

Renewable energy

Electricity generationForecastMeasured
Renewables Technology--
Other Renewables Tech--
Electricity consumed by generation --
Primary energy requirement
offset by renewable generation
118 kWh/m².yr 62 kWh/m².yr
Annual CO₂ emissions
offset by renewable generation
24 kg CO₂/m².yr 11 kg CO₂/m².yr

Calculation and targets

Whole house energy calculation method PHPP
Other whole house calculation method-
Energy target AECB Silver
Other energy targets-
Forecast heating load 19 W/m² demand

Airtightness

 DateResult
Pre-development air permeability test21 February 201211.1m³/m².hr @ 50 Pascals
Final air permeability test21 October 20132.3m³/m².hr @ 50 Pascals

Project description

StageOccupied
Start date11 February 2013
Occupation date14 November 2013
Location London London  England
Build typeRefurbishment
Building sectorPrivate Residential
Property typeSemi-Detached
Construction typeSolid Brick
Other construction typeTop 3 storeys brick, lower storey lime rendered
Party wall constructionSolid brick
Floor area 170
Floor area calculation method Treated Floor Area (PHPP)
Building certification  AECB silver standard certified building AECB silver standard certified building

Project Team

OrganisationArboreal Architecture
Project lead personArboreal Architecture - Harry Paticas
Landlord or ClientAnonymous
ArchitectArboreal Architecture - Harry Paticas
Mechanical & electrical consultant Alan Clarke
Energy consultantHarry Paticas and Alan Clarke
Structural engineerThe Morton Partnership
Quantity surveyor
ConsultantJennings Aldas (Air Leakage Specialist)
ContractorNoble & Taylor

Design strategies

Planned occupancyTwo people with occasional guests. Both occupants have their own home-office.
Space heating strategyLow temperature hot water heating.Gas-fired 12kW condensing boiler.
Water heating strategyUnvented hot water cylinder with solar twin coil.
Fuel strategyMains gas. Mains electricity.
Renewable energy strategySolar hot water collectors. 3sqm facing due south.
Passive Solar strategyn/a - retrofit of existing listed building.
Space cooling strategyNatural cross-ventilation.
Daylighting strategyn/a - retrofit of existing listed building.
Ventilation strategyWhole house mechanical extract ventilation.
Airtightness strategy Continuous air barrier formed by internal lime plaster and poured screed floor with vapour check membrane below. 2nd floor ceiling membrane sealed with tape and mesh to plaster walls. Joist ends and door/window frames sealed with tapes. Grommets installed to all services penetrations.
Strategy for minimising thermal bridges Continuous layer of internal insulation. Careful detailing of a range of insulation materials including: aerogel blanket, perlite, technopor, perinsul.
Modelling strategyWhole house modelling in PHPP.
Insulation strategyApplication of Internal wall insulation including: woodfibre, aerogel, IQtherm, PIR, calsitherm, rigid thermoset insulation.Existing concrete slab retained but screed removed and replaced with vacuum insulated panels and lytag screed.2nd floor roof filled with cellulose insulation between TGI joists.
Other relevant retrofit strategiesPre-design investigations undertaken to develop an holistic understanding of the existing structure in order to allow a fine grain of design.
Contextual informationThe existing building is Grade II listed.

Building services

OccupancyTwo people with frequent guests.
Space heatingLow temperature hot water heating.Gas-fired 12kW condensing boiler.
Hot waterUnvented hot water cylinder with solar twin coil.
VentilationWhole house mechanical extract ventilation.
ControlsDigital controller with room temperature compensation, hot water programme and control of solar thermal. Integral isolating and thermostatic radiators valves to all radiators.
CookingGas hob with electric oven.
LightingLED lighting throughout.
AppliancesAll appliances A+ to A+++ rated.
Renewable energy generation systemSolar hot water collectors. 3sqm facing due south.
Strategy for minimising thermal bridgesContinuous layer of internal insulation. Careful detailing of a range of insulation materials including: aerogel blanket, perlite, technopor, perinsul.

Building construction

Storeys 4
Volume 613
Thermal fabric area 376
Roof description Insulated 2nd floor ceiling with cold (but windtight) roof above. TGI joists with blown cellulose.
Roof U-value 0.15 W/m² K
Walls description Internal wall insulation including: woodfibre, aerogel, IQtherm, PIR, calsitherm, rigid thermoset insulation.
Walls U-value 0.11 W/m² K
Party walls description Solid brick. Party wall returns to external walls insulated (u-value = 0.63).
Party walls U-value 1.21 W/m² K
Floor description 30mm vacuum insulated panels with lytag screed over.
Floor U-value 0.25 W/m² K
Glazed doors description Thermally broken (20mm purenit) hardwood frames with single outer glazing and secondary double glazing (argon filled).
Glazed doors U-value 1.10 W/m² K uninstalled
Opaque doors description Existing door panels upgraded with 30mm VIPs with purenit battens and 10mm VIP sheet.
Opaque doors U-value 0.90 W/m² K uninstalled
Windows description Existing single glazed sash windows with secondary double glazing (argon filled).
Windows U-value 1.25 W/m² K -
Windows energy transmittance (G-value) 60 %
Windows light transmittance 67%
Rooflights description conservation rooflight installed outside of thermal envelope.
Rooflights light transmittance -
Rooflights U-value -

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