Project Description. Projected build start date 02 Aug 2010 Projected date of occupation 03 Dec

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1 Project name Hounslow Council Passivhaus Retrofit - and the development of a decision making matrix Project summary The house is a 3-bedroom semi-detached single-family dwelling built in the early 1950s. The property is located in Hounslow close to Heathrow airport, and is not located within a conservation area. We propose a Passivhaus refurbishment including external insulation, roof insulation, triple glazed windows and heat recovery ventilation. German best practice techniques in low-energy building design, as evolved by the Passivhaus Institute in Darmstadt, have kick-started a revolution in construction practices. Frequently achieving a remarkable Factor-10 reduction in typical space heating energy demand, Passivhaus success is contingent upon using a whole-house approach. Project Description Projected build start date 02 Aug 2010 Projected date of occupation 03 Dec 2010 Project stage Under construction Project location London, London, England Energy target Retrofit for the Future Build type Refurbishment Low Energy Buildings Page 1

2 Building sector Public Residential Property type Semi-Detached Existing external wall construction Solid Brick Existing external wall additional information Solid brick with pebbledash render Existing party wall construction Solid brick Floor area m² Floor area calculation method PHPP Project team Organisation Project lead Client Architect Mechanical & electrical consultant(s) Energy consultant(s) Structural engineer Quantity surveyor Other consultant Contractor Bere Associates Limited bere:architects Hounslow Homes bere:architects Alan Clarke Energy Consultant and Building Services Engineer Alan Clarke Energy Consultant and Building Services Engineer Rodrigues Associates e-griffin Consulting Not yet selected Design strategies Planned occupancy Space heating strategy Water heating strategy Fuel strategy Renewable energy generation strategy Passive solar strategy 3 people To use existing radiator system. New boiler to be Viessmann storage combi with 250 litres of storage for use with solar panels. The unit is compact and can fit in the kitchen, and provides all heating and hot water services in one pre-plumbed and configured unit for rapid installation. The Viessmann unit has built in solar hot water heat exchanger, pump and controls, for quick connection to roof mounted solar hot water panels. These are estimated to provide 70% of hot water requirement. the location of the hot water storage in the kitchen enables very short deadlegs to the kitchen tap and the bathroom on the first floor, minimising wastage of hot water. Mains gas and electricity, as existing. None Passive solar gains are constrained by working with existing window openings. Low Energy Buildings Page 2

3 Space cooling strategy Daylighting strategy Ventilation strategy Airtightness strategy Strategy for minimising thermal bridges Modelling strategy Insulation strategy Other relevant retrofit strategies The mechanical ventilation system has controls that provide for automatic summer bypass of the heat exchanger, depending on temperature, so free-cooling, including night cooling, can be provided. This enables cooling and ventilation to be provided without opening windows if desired for sound insulation. The automatic controls also switch back to using the heat exchanger if external temperature is above internal. Existing daylighting is good, and window areas are maintained. Whole house ventilation with passivhaus mechanical heat recovery ventilation unit. This is located in the warm loft, because of space constraints in the house, with supply and extract ductwork able to use the loft space for distribution. Preliminary testing to help site identify air leakage routes. External air barrier on walls joining over-rafter barrier in recovered roof. windows sealed to external face of wall. Services penetrations sealed at the air barrier. Passivhaus detailing around windows and other openings. Particular care and supervision of M&E penetrations. Careful detailing and site supervision. External insulation to be continuous over walls, and roof insulation extended over rafters to be continuous with wall insulation at eaves. Below ground perimeter insulation at base of wall to address thermal bridge here. PHPP for energy and summer overheating Heat for thermal bridging External 300mm polystyrene system with render over (the house is currently rendered) to give U-value of Roof insulation 300mm mineral fibre and 100mm wood fibre to give U-value 0.11 Floor insulation 200mm below relaid floor slab/screed Passivhaus windows overall U=0.8 The current occupants remain in the house. Disturbance to be kept to a minimum, though they need to move out for insulation to the floor. Low Energy Buildings Page 3

4 Other information (constraints or opportunities influencing project design or outcomes) We have had a meeting with Houslow Planning department, the planning department supports the broad aims of the project and welcome the benefits it will bring to our residents. It is great that we are one of the pilot Councils for the project. As discussed, the works will require planning consent given the thickness of the insulation that is usually required and the resultant alteration to the house(s). In cases such as (this), where there are no key features in the street scene or the individual house and there are no conservation area restrictions, the planning consent process should be fairly straightforward. Energy use Fuel use by type (kwh/yr) Fuel previous forecast measured Electri c Gas Oil LPG Wood Primary energy requirement & CO2 emissions Annual CO2 emissions (kg CO2/m².yr) Primary energy requirement (kwh/m².yr) previous forecast measured Renewable energy (kwh/yr) Renewables technology forecast measured - - Energy consumed by generation Airtightness ( 50 Pascals ) Date of test Test result Pre-development airtightness Final airtightness Space heat demand Annual space heat demand ( kwh/m².yr ) Pre-development forecast measured Low Energy Buildings Page 4

5 Whole house energy calculation method Other energy calculation method Predicted heating load Other energy target(s) PHPP 12 W/m² (demand) Air tightness target 0.6h-1 (air changes per hour) Building services Occupancy Space heating Hot water Ventilation Controls Cooking Lighting Appliances Renewables Strategy for minimising thermal bridges Building construction Storeys Volume Thermal fabric area Roof description Roof U-value Walls description Walls U-value Party walls description Party walls U-value Floor description Floor U-value Glazed doors description Glazed doors U-value Opaque doors description Opaque doors U-value Windows description Windows U-value Windows energy transmittance (G-value) Windows light transmittance Rooflights description 0.00W/m² K 0.00W/m² K 0.00W/m² K 0.00W/m² K 0.00W/m² K 0.00W/m² K 0.00W/m² K Low Energy Buildings Page 5

6 Rooflights light transmittance Rooflights U-value 0.00W/m² K Low Energy Buildings Page 6

7 Project images Low Energy Buildings Page 7

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