Orientation and Materials:

Each of the four office buildings is organized around an enclosed, daylit four-storey atrium, which maximizes fresh air and natural light. The floor plates are optimized in size and shape to give around 1500 m² per floor, all occupants being within 5•4 m of an operable window. The roof profiles curve to enhance both daylighting and the potential for photovoltaic placement. PVC and other perceived toxic materials have been banned. The timber floor of the gymnasium is made from sustainable woodland, while the floors to the offices are constructed from recycled sports shoes.

All rainwater is stored and used for lavatories and garden irrigation.

Low energy solutions have translated into a thick and highly insulated envelope, with 620 mm walls packed with 140 mm of Rockwool, giving a calculated thermal conductivity from 0•4 to 0•25 W/m²K. With even thicker insulation in the roofs, these low energy measures cost an extra £30 000. Improved fenestration and a 36% glazing ratio added a further £16 500 to the bill. These measures, combined with a naturally ventilated garage for 327 cars, produced buildings with a low requirement for thermal energy. That said, the building is equipped with fan coil units, these are run off ground water for direct cooling. The building’s heating runs off the local district heating system.

Four office buildings have blinds on three floors to shield against low level sun, especially from the more intrusive western aspect. Top floor glazing is largely set back, with a roof overhang and an internal reflective rooflight.

Environmental Engineering:

Thermal energy from an aquifer provides the essential source to cope with cooling loads. Ground water is used in the air handling units for computer rooms, and the fan coil units, which are located behind suspended ceilings in the usual fashion. At times of peak demand the heat pumps boost the ground water, functioning like a normal watercooling chiller with a dry cooler. This cooler can also provide free cooling when external temperatures fall below 68C. When extra heat is required the heat pump pulls a final top-up from the neighborhood district heating system. As the buildings possess high thermal capacities, no perimeter heating has been deemed necessary. The only use of radiators is on the fourth floors, where larger glazed areas and light steel construction requires some radiant heating.

All the buildings recycle rainwater, which is stored in underground tanks. The collected water is filtered, stored and then pumped to supply the toilets, kitchens and washing facilities. Make-up water comes from conventional potable mains supplies. Within a total construction cost of £150 million, the extra cost for these energy saving technologies has been put at about £1 million, with a payback period estimated at five to seven years. Also important to Nike were the favorable tax concessions and grants which covered half of the extra capital cost.