Air change rates in multi-family residential buildings in northern Portugal

Existing technical recommendations and standards regarding natural ventilation in Portugalestablish one air change rate, ACH, in main rooms (bedrooms and living rooms) and fourACH in service rooms (kitchens and bathrooms). Admittedly these rates are not beingobserved in most residential buildings recently erected in Portugal.Two trials (May 2002 and January 2003, lasting approximately 2 weeks each) were carriedout for the purpose of estimating the implementation of the rates in a two-bedroom flat whichis inhabited and equipped with a mixed ventilation system: intake via self-adjustingventilation inlets in the living room and bedrooms, natural exhaust in the bathroom assistedby discontinuous mechanical extraction in the kitchen.Some conclusions can be drawn regarding the efficiency of the ventilation system used,namely the results of the study shows that the measured ventilation rate was irregular andlower than the Portuguese recommendations during both seasons.