As well as the building physics, BedZed can claim several other sustainability successes, not least a water strategy that will cut demand by a third.
Up to 150m3 of rainwater is collected and stored in underground tanks and pumped as grey water for flushing toilets and watering gardens. A living technology machine comprising a system of septic tanks and biological reed bed filters treats up to 50m3/day of effluent and recycles it back into the grey water tanks.
Photovoltaic cells, initially discounted on the grounds of cost, have been added at a late stage thanks to a grant from the European Union. Mounted on the roof of each terrace the PV cells will provide enough power for a pool of 40 cars, available to residents for local journeys. 'An electric car may only have the range of 100km, but it is a fact that in excess of 98% of all car journeys are less than 40km, ' explains Twinn. 'And you can run a car on PV for just 1p/km.'
Sustainability even extends to the materials used in construction. 90% of the 120t of steel used on site was recovered from scrap before it went into the energyintensive recycling process, explains structural engineer Ellis & Moore project director Lachlan McDonald.
Structural capacity of the steel sections was calculated from historic tables, with compromises made on size, wastage and visual inspection.
A 10% saving was made on the raw material cost.
Re-using structural timber proved much more difficult, says McDonald.
'Quality was very difficult to guarantee and each batch had to be stress graded. In both reused steel and timber there is much good quality material available. If only the suppliers knew what they were selling it could be sold as new.'