Poor quality interior climate conditions are estimated to cost Norwegian society between 8 and 12 billion kroner annually. Added to this is lost income resulting from reduced productivity. The interior climate conditions of kindergartens and schools are crucial to health and learning capability.In modern commercial office buildings technical installations account for about 50 percent of the costs of which ventilation represents a major component. Buildings account for half of Norway's energy consumption. It is therefore important to develop reliable and economically reasonable concepts which contribute to reducing running costs and investment, while at the same time providing adequate interior climate quality.