Almshouses, Cambridge

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This project will focus on a mid-terrace, 1-bed almshouse property in Cambridge. Our approach to energy saving and CO2 reduction is to follow a lean-clean-green hierarchy: seeking to minimise heat losses from the property thermal fabric and ventilation method; to supply residual space and water heating using replicable, low carbon technology; to minimise lighting and appliance energy loads; and finally to consider micro-generation using proven, renewable energy systems.

Retrofit for the future ZA445E
Images Graphs Figures Description Strategies Building

Almshouses, Cambridge : 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 16193 kWh/yr 506 kWh/yr -
Natural gas use- 4093 kWh/yr -
Oil use- - -
LPG use- - -
Wood use- - -
Other Fuel - - -
Primary energy requirement 1511 kWh/m².yr 223 kWh/m².yr -
Annual CO₂ emissions 357 kg CO₂/m².yr 43 kg CO₂/m².yr -
Annual space heat demand - 79 kWh/m².yr -

Renewable energy

Electricity generationForecastMeasured
PV544 kWh/yr -
Micro CHP gas453 kWh/yr -
Electricity consumed by generation --
Primary energy requirement
offset by renewable generation
130 kWh/m².yr -
Annual CO₂ emissions
offset by renewable generation
21 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 -


Pre-development air permeability test-6.8m³/m².hr @ 50 Pascals
Final air permeability test-3.74m³/m².hr @ 50 Pascals

Project description

StageUnder construction
Start date01 February 2010
Occupation date28 June 2010
Location Cambridge Cambridgeshire  England
Build typeRefurbishment
Building sectorPublic Residential
Property typeSemi-Detached
Construction typeSolid Brick
Other construction type
Party wall constructionSolid Brick
Floor area 26.8
Floor area calculation method Treated Floor Area (PHPP)
Building certification

Project Team

OrganisationCambridge Housing Society
Project lead personCambridge Housing Society, Endurance House, Chivers Way, Histon, Cambridge, CB24 9ZR
Landlord or ClientCambridge Housing Society, Endurance House, Chivers Way, Histon, Cambridge, CB24 9ZR
ArchitectEnergy Conscious design, Studio 3, Blue lion Place 237 Long Lane, London SE1 4PU
Mechanical & electrical consultant Environmental Design Associates, 31 Wick Road, Teddington, Middlesex, TW11 9DN
Energy consultantECD Project Services, Studio 3, Blue lion Place 237 Long Lane, London SE1 4PU
Structural engineerCarter Clack Partnership, 49 Romney Street, Westminster, London, SW1P 3RF
Quantity surveyorThe Keegans Group, Studio 2, 193-197 Long Lane, London, SE1 4PD
ConsultantPublic Participation, Consultation and Research, Studio 2, 193-197 Long Lane, London, SE1 4PD
ContractorRoalco Ltd, Ardleigh House, Dedham road, Ardleigh, Colchester, Essex, CO7 7QA

Design strategies

Planned occupancyProperty is currently void, but suitable new tenants will be found who buy into the monitoring strategy. They will be fully briefed on their new home and given a simple home information pack to explain the various technologies and controls along with local community facilities, recycling centers and public transport.
Space heating strategyHeating will be provided by mains gas via a micro CHP unit and new radiators. Heat will be recovered from exhaust air via the use of mechanical ventilation with high efficiency heat recovery unit.
Water heating strategyHot water will be provided by mains gas via a micro CHP unit and new hot water cylinder
Fuel strategyMains Gas, Mains electricity
Renewable energy strategyOnsite electric production by 0.7 kWp photovoltaic panels and low carbon electricity production via gas fired micro CHP unit.
Passive Solar strategyAs this is a retrofit of a historic building within an area of architectural merit , options for reconfiguration of fenestration to improve passive solar gain will not be possible.
Space cooling strategyHRV with summer bypass combined with natural ventilation for summer period. Night purging during heat waves.
Daylighting strategyAs this is a retrofit of a historic building within an area of architectural merit , options for reconfiguration of fenestration to improve daylight levels will not be possible.
Ventilation strategyHeat recovery ventilation and additional natural ventilation by opening windows during summer months as required.
Airtightness strategy All existing vents and chimneys blocked up. New air barrier created by OSB board at ceiling level with taped joints and perimeters taped to masonry walls and plastered over. Service void created bellow this to eliminated penetrations. Windows, floors, junctions and all penetrations sealed with proprietary air tight tapes, membranes and grommets. All voids such as cavities filled to mitigate thermal bypass.
Strategy for minimising thermal bridges Continuous insulation maintained throughout. Geometric thermal bridges minimised. Junctions assessed include: Ground floor junction, external corner, party wall, party roof, party floor, eaves, verge, window jamb, head and sill, door jamb, head and threshold. Internal insulation has been returned on party walls.
Modelling strategyWhole house modeling was undertaken in SAP, with the use of extension sheet produced for this competition. Dynamic simulation was used to assess the impact of our proposed micro CHP heating system with the results fed back into the SAP extension sheet.
Insulation strategy- The existing solid floor will be insulted with a thin layer of aerogel laminated chipboard to achieve a U-value of 0.54 w/m2K - The existing solid walls will be dry lined internally with a high performance aerogel laminated board to achieve a U-value
Other relevant retrofit strategiesWe propose to fit an intelligent heating controller designed to save energy and improve comfort in residential buildings. The system controls both central and water heating, reducing energy consumption by automatically monitoring and learning occupant behavior and preferences. It also provides an easy to use and simply user interface as well as covering all energy monitoring requirements. We also propose to carry out additional monitoring of the innovative heat saving thermal blinds.
Contextual informationCambridge Housing Society manages over 2200 homes and provides care and support services for 520 people. This project will focus on a particular housing archetype - the almshouse - and will seek to establish a complementary and replicable set of measures which significantly reduce energy use and CO2 emissions. The challenges to low carbon retrofit presented by this property typify many of the issues prevalent in this housing type: uninsulated solid wall construction, poor quality single glazing, sensitive architectural character etc. It is intended that the findings will inform the remainder of Cambridge Housing Society's historic properties and will thus be widely applicable to other social landlords or building owners with similar stock.

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