The principal objective of the design was to reduce energy demand to ‘passivhaus’ standards,
with the remaining energy demand covered as far as possible from renewable sources, while
simultaneously providing occupants with a high standard of comfort. Heating loads were
minimized by the use of a high level of insulation and limited glazing area with the aim of
reducing heating consumption to 15 kWh/m². Infiltration losses were reduced by designing
for an air tightness of 0.6 ach at 50 Pa. Heating is supplied using an air distribution system and
ceiling panels in the office and seminar rooms, supplemented by underfloor heating in the atrium
area. The air supply system, incorporates heat recovery in the form of air to air heat exchangers,
with efficiencies in the range 78% to 86%. The heating systems are supplied with water
heated by a heat pump (43 kW; COP = 4) which uses water circulated through pipes in
deep boreholes as its source. In summer, cooling is provided by circulating this
water through the ceiling panels and heat exchangers in the air supply system.
Additional reduction in peak summer temperatures is achieved by using high thermal mass in
the interior of the building and night-time natural ventilation. In addition domestic hot water is
served by 5 m² solar collector. Photovoltaic collectors on the façade and roof provide 9.8 kWpeak
The building was completed in 2003 and serves a missionary organisation dispatching goods to developing countries. Its use is multifunctional, serving to provide office accommodation, seminar rooms, restaurant and exhibition facilities, warehousing and a loading bay. It consists of three floors and a basement. Office and public areas are occupied by 40 people and have an area of 1 215 m². The remaining building area is used for parking vehicles (325 m²) and a basement (550 m²). The building is semi-circular with a central atrium.