The building is naturally ventilated, except for toilets and kitchen which are required by Danish
building regulations to have a mechanical exhaust. Natural ventilation is automatically controlled, but
users have a possibility for manual control (opening windows) and can change the control strategy
in the building, if needed. The natural ventilation principle is combined with the night cooling strategy,
which is activated during warmer seasons.
The design of Spirehuset makes use of both cross and stack natural ventilation principles. Stack ventilation operates with lower air inlets located in the windows, at a normal window height, and upper exhaust openings located in the roof. The air enters smaller zones, on the periphery of the building. Air moves from these to the large common room, located in the centre of Spirehuset. To encourage the stack effect, the roof of the common room is designed to be higher than those of the other rooms. If the concentration of carbon dioxide or air temperature in a smaller zone exceeds the set point, then the roof openings in the zone are also activated to provide exhaust openings.