Technical procurement of demand controlled ventilation for dwellings based on performance specifications.

Swedish dwellings often have mechanical ventilation with an almost constant air flow independent of variations in loads. The performance of these ventilation systems is often not satisfying. The occupant habits have changed e.g. increased moisture load. Therefore a technical procurement for energy efficient demand controlled ventilation systems was initiated. First the building regulations were analysed, then the parameters relevant for indoor air quality in dwellings and the energy efficiency potential were determined. Directions for the technical procurement including detailed performance specifications were produced. The proposed ventilation systems were evaluated using calculations and laboratory tests. The performance specifications included maximum levels of carbon dioxide, relative humidity, sound, and a minimum ventilation rate (no one at home), odour-capturing ability for cooker hood, maximum use of electricity for ventilation etc. Two of the proposed ventilation systems fulfilled the specifications and were tested in an apartment and found to perform satisfactorily.