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Deep retrofit of 1961 linked detached
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5Pev : 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 1400 kWh/yr 900 kWh/yr 1003 kWh/yr
Natural gas use12700 kWh/yr 2600 kWh/yr 2707 kWh/yr
Oil use- - -
LPG use- - -
Wood use- - -
Other Fuel - - -
Primary energy requirement 216 kWh/m².yr 62 kWh/m².yr 67 kWh/m².yr
Annual CO₂ emissions 41 kg CO₂/m².yr 13 kg CO₂/m².yr 14 kg CO₂/m².yr
Annual space heat demand - 20 kWh/m².yr -

Renewable energy

Electricity generationForecastMeasured
PV-3100 kWh/yr
Other Renewables Tech--
Electricity consumed by generation --
Primary energy requirement
offset by renewable generation
62 kWh/m².yr -25 kWh/m².yr
Annual CO₂ emissions
offset by renewable generation
13 kg CO₂/m².yr -8 kg CO₂/m².yr

Calculation and targets

Whole house energy calculation method SAP
Other whole house calculation method-
Energy target
Other energy targets-
Forecast heating load 1800 W/m² demand


Pre-development air permeability test05 December 201315m³/m².hr @ 50 Pascals
Final air permeability test04 December 20140.75m³/m².hr @ 50 Pascals

Project description

Start date01 May 2014
Occupation date01 December 2014
Location Chorlton Manchester  England
Build typeRefurbishment
Building sectorPrivate Residential
Property typeDetached
Construction typeMasonry Cavity
Other construction typeBrick and hollow block with 50mm UF filled cavity
Party wall construction
Floor area 84
Floor area calculation method Actual Floor Area (SAP)
Building certification

Project Team

OrganisationWaxwing Energy
Project lead personGervase Mangwana
Landlord or ClientSonia Mangwana
Mechanical & electrical consultant
Energy consultantNick Parsons
Structural engineer
Quantity surveyor

Design strategies

Planned occupancyTwo Adults and one baby born 6 months after occupancy. One adult working at any one time not always away from home during day.
Space heating strategyMains gas system boiler 12 kW. Underfloor heating to ground floor. Rads in office and bathroom. Bedrooms unheated. Mechanical Ventilation with Heat recovery.
Water heating strategy150l cylinder heated via gas boiler. Surplus generated electricity from PV array diverted to immersion when available.
Fuel strategyMains Gas. Mains electricity. PV electricity
Renewable energy strategy3.3 kWp array installed 2011
Passive Solar strategyHouse within 15 of south. Glazing not optimised. Overheating now occurring.
Space cooling strategyNatural ventilation for most of the cooling season. Daytime use of MVHR with night purging during heat waves.
Daylighting strategyUnknown
Ventilation strategyMVHR via radial semi flexible ducting system supplying 5 habitable areas and 5 wet rooms
Airtightness strategy Target of 2 m3/m2/h. The full strip out gave the opportunity to complete a total airtight layer.
Strategy for minimising thermal bridges Designed out as far as possible. Ceiling joists run through to eaves. One continuous bridge on front plinth wall where aerated block is used to mitigate.
Modelling strategyVery basic heatloss calculations
Insulation strategyInternal PIR to cavity walls. Same to timber frame front and back with woodfibre external to allow vapour to permeate outwards.
Other relevant retrofit strategiesAttempted to reuse as much as possible from original house. For example staircase was removed and stored in the garden whilst the internal walls were insulated.
Contextual informationThe biggest constraints were a self imposed budget of 60,000 (actual 75k) and project length of 6 months (actual 7). These precluded extensions that were considered. Also affected choice of glazing.

Building services

Occupancy2 adults one very young child
Space heatingAs design
Hot waterAs design
VentilationAs design
Controlsas design
CookingGas hob, electric oven
LightingLed throughout
AppliancesA+++ washing machineA++ Fridge freezer
Renewable energy generation systemAs pre build
Strategy for minimising thermal bridgesAs design

Building construction

Storeys 2
Volume 210
Thermal fabric area 206
Roof description Cold roof insulated at ceiling height with a mix of mineral wool and PIR at the edges where roof slope limits full fill
Roof U-value 0.10 W/m² K
Walls description Cavity walls pre filled and then internally insulated with PIR. Stud walls internally insulated with PIR, filled with mineral wool and externally insulated with wood fibre.
Walls U-value 0.15 W/m² K
Party walls description none
Party walls U-value -
Floor description Dry screed raft on PIR
Floor U-value 0.12 W/m² K
Glazed doors description uPVC 40mm triple glazed
Glazed doors U-value 1.00 W/m² K uninstalled
Opaque doors description None
Opaque doors U-value - -
Windows description Downstairs uPVC 40mm triple glazedUpstairs existing double glazed frames reglazed with low-e, warm spacer, argon filled 28mm units
Windows U-value 1.00 W/m² K -
Windows energy transmittance (G-value) 0.58 %
Windows light transmittance 0.74%
Rooflights description none
Rooflights light transmittance -
Rooflights U-value -