Ecotecture was approached by clients who had bought an old, inappropriately extended, and energy-hungry 420 square metre building, located in the cathedral city of Chichester, and wanted to design a more dynamic and contemporary solution.
Using the existing planning permission and employing the services of DMH Stallard Planning Consultants, a comprehensive case for this sensitive building in the Sussex Downs area of outstanding natural beauty was approved at Committee at the beginning of 2009.
The core idea behind the building design was pushing the envelope whilst maintaining the balance between energy efficiency and high design concept. The building has been thermally modelled and shows that the curved design does not compromise the performance, in-fact this specific design actually enhances it.
The building is crescent-shaped, cut into the hillside with the upper levels sliding partially over the lower levels. The design has taken into account ecological features such as grassed roof areas which further allow the building to sink into the Sussex landscape in contrast to the modern glazing.
Overall, the design for this innovative building was to draw the garden with its views over the Sussex Downs into the house and take full advantage of the orientation of the sun to include Passivhaus principles, shading itself during the day using passive solar gains when appropriate, and distributing the heat throughout the building using a natural ventilation strategy in conjunction with a mechanical ventilation heat recovery system (MVHR).
The building has been modelled using the Passivhaus planning pack as part of the original design process. The ventilation system is well recognised as a common feature of excellent quality green architecture, the windows are also Passivhaus certified and are primarily timber windows with an aluminium coating; supplied by Optiwin, with a U value of 0.8Kw/m2/K. The use of superior levels of insulation and locked-in thermal mass will affect the internal environment to a considerable extent, and once the building is sealed airtight and heat recovery and ventilation are introduced, the positive effect on the internal environment will be amplified. The equipment within the building will provide most of the heat demand for the building and this is typical of Passivhaus architecture.
The design of this contemporary building provides roof-mounted solar hot water and photovoltaics for the supply of electricity and hot water. Other ecological measures include rainwater harvesting and appropriate accommodation to house a local bat population.
The building is very strong in its form and will be finished in a self-coloured render which will work well with the curves to produce a soft finish. This in conjunction with the curved lines of the deck, the additional landscaping and the brise soleil will sit the building down into the Sussex landscape and produce a building of exceptional architectural merit.