However, the most innovative aspect of the building is the introduction of thermal earth ducts, designed to provide a source of passive heating and cooling through the building.
Operation of the Earth Ducts: Operating under the suction pressure created by the supply air handling unit, fresh air is drawn through a series of cylindrical turrets located around the site. The air is subsequently entrained through the 900mm dia. x 100m long earth ducts respectively buried at a depth of 2m. As the entrained air passes through the ducts, the surrounding soil held at a constant 13oC provides a degree of pre-heat or colth to the ventilation system.
During the winter months, the temperature of the pre-heated fresh air, mixed with a degree of recirculated air, is boosted via conventional LPHW heater batteries. This tempered air is injected into the pressurised floor plenum and subsequently discharges into the occupied office space via a series of swirl diffusers. During the summer months, with the fresh air maintained at a temperature of circa 14 / 15oC, there is no requirement for mechanical cooling.
=In essence the earth duct system provides "free pre-heat" and "free comfort cooling" – with energy savings calculated to be in the region of 75%
