Simple and reliable systems for demand controlled ventilation in apartments.

The paper is presenting experience from a several year long time of operation in a group of apartment buildings in the Stockholm area, Sweden, having an extremely low energy usage, less that 110kWh/(m2.year), electricity supply to the building services included. The system solution used has a very low pressure drop in the exhaust ducts. Every exhaust point is connected to an individual duct leading to a fan chamber in the attic. The pressure in that chamber is kept constant. The attendant in a flat wanting a higher flow rate starts an individual booster fan situated at the top of his own duct. Supply air is furnished by valves installed in the external walls of the flat. Balancing is made in the fan chamber only. Thus nobody can arrange a higher base flow rate for an individual flat without having access to the fan chamber. The investment level is comparable to that of a traditional system. Duct dimensions are chosen so as to allow them to be built-in into the walls. The system, which was designed by Mr Henry Willman of HEWAB Engineering, Stockholm, is applicable for offices and the like with or without a mechanical air supply system.