Affordable, sustainable housing for Exeter
For Exeter City Council; £2.1m contract value; completion 2011
The building design is based on the ‘Passivhaus’ methodology and together with Rowan House will be amongst the first multi-residential certified passive houses in the UK.
The design seeks to achieve a contemporary interpretation of vernacular residential forms. The asymmetric window arrangements on the gable ends contrasts with the symmetrical flank elevations. In combination with the change in facade material this adds interest and results in a playful design solution. The resulting arrangement is sympathetic to the surrounding residential area both in scale and detail.
Carefully scaled windows allow for optimum daylight and solar gain levels for enhanced environmental performance. The quality of materials and good quality fenestration offers residents a sense of a place with a distinctive modern character which they can take pride in over the long term.
Access galleries provide circulation between units and sit partially behind the facade. This clearly indicates the entrance and circulation routes whilst allowing them to be semi-protected from the elements.
Exemplar sustainable housing that is fully accessible according to Lifetime Homes Standards, specifically intended to encourage existing tenants to down-size.
Low Energy Design including:
- Thermal mass - Thermal mass reduces internal temperature fluctuations and reduces the risk of overheating in summer
- Super Insulated Building Envelope - masonry walls are externally insulated and rendered to achieve high insulation levels and a U value no greater than 0.15W/m²K. A clay tiled insulated roof construction achieves a U value no greater than 0.10W/m²K and an insulated floor construction also achieves no greater than 0.10W/m²K. All windows and doors are to be high performance with timber frames achieving a minimum U value of 0.85W/m²K.
- Minimal Thermal Bridging
- Mechanical ventilation with high efficiency heat recovery – minimising ventilation heat losses through controlled ventilation, ensuring optimum indoor air quality and reduced heating requirements by retaining energy from exhaust air
- High Levels of Air Tightness – less than 0.6 air changes per hour
- Daylight design – is maximised in all spaces and habitable rooms where possible to reduce reliance on artificial light and utilize solar gain
- Low water use strategies – use of low water use appliances significantly reduce mains water consumption below 80l/person/day
- Low carbon technologies and onsite renewables – Solar hot water panels for each individual flat provide energy efficient hot water
- Ecological landscape design strategies – all communal and private gardens have been designed to follow permaculture principles and wildlife ‘corridors’ link the site to the existing local ecology
This holistic passive design strategy allows the units to be operated without a conventional heating system. At the same time it will avoid overheating in summer and aims to have a minimal environmental impact.
Material Selection and Healthy Buildings
Building materials and components have been carefully chosen to meet the performance requirements of a low energy building. This includes considering materials according to the following principles:
- Natural / recycled materials where practical
- Low VOC organic paints, waxes and stains throughout
- Specification of timber from sustainably managed woodlands (e.g. FSC certified)
- Avoiding the use of PVC by careful product selection (e.g. LSF electrical cabling, clay underground pipe-work, ABS water pipes, timber fascias, soffits and barge boards, timber windows and doors)
- Reduced use of heavy metals (e.g. lead flashings to be stainless steel or zinc)
- Electrical wiring in the bedrooms is radial to lessen the impact of electromagnetic fields (EMF’s)
- The building will be tested to ensure that sound transmission between flats is improved beyond the requirements of Part E of the Building Regulations.
- Use of sustainably sourced materials to ISO 14001
- Use of materials with low embodied energy, where appropriate
- Locally sourced materials, wherever possible
- Prevention of dust-mite infestation by specification of easily cleanable surfaces