Indoor environment quality in wooden family houses was compared to bricked houses or concrete slab apartments. Based on measurements, the influence of selected systems of forced ventilation without heat recovery and with efficient heat recovery were compared in selected houses in consideration of monitored parameters of CO2 and relative humidity in the course of 24 hours. Auxiliary parameters such as temperature and absolute pressure were also measured. The CO2 and relative humidity parameters had demonstrable effects in all the houses. The differences of CO2 values while using recuperation or not in wooden houses reached 21.2%, 44.7%, and 31.6%. The relative humidity value differences reached 6.6%, 2.8%, and 2.9%. More significant differences in values were reached in the course of measuring in a brick building – 73.1% CO2 and 39.4% of relative humidity. In the concrete slab apartment, the value differences reached 46.1% CO2 and 1.8% at relative humidity. The permitted limit of 1,500 ppm of CO2 was exceeded in all the objects without active heat recovery. In the case of efficient heat recovery, the values oscillated around the recommended value of 1,000 ppm of CO2.