Improved ventilation combined with energy efficiency in naturally ventilated houses.

Modern one-family houses in Scandinavia built before 1980 are often naturally ventilated and heated by electric baseboard heaters. The overall supply of fresh air is often inadequate during the heating season in many of these houses. Long periods of time individual rooms might get too little fresh air. The performance of a natural ventilation system is very much dependant upon the overall airtightness and the distribution of the airtightness of the building and the weather. This paper examines the performance of six modern one-family houses before and after the ventilation system was improved. Different means of improving ventilation are described. The constant concentration tracer gas technique was used to examine the supply of fresh air. Fan pressurization combined with infrared photography were employed to characterize the air leakage of the building. A simplified theoretical model was used to further evaluate the measurements. It is obvious from the tested houses that the overall ventilation and the ventilation of individual rooms were improved. The ventilation losses were increased and therefore energy conserving measures had to be taken. The overall costs were high compared with the energy savings obtained.