Influence of different ventilation levels on indoor air quality and energy savings: A case study of a single-family house

In all cases, the sensor was positioned in the exhaust duct exiting from habitable spaces. Measurements showed that, for case I, the CO2 concentration reached over 1300 ppm, which was higher than the commonly referenced threshold for ventilation control, i.e. 1000 ppm, showing unacceptable IAQ. In case II, the CO2 level was always below 950 ppm, indicating that 0.20 L s−1 m−2 is a sufficient ventilation rate for the reference building. The case III showed that the ventilation rate of 0.35 L s−1 m−2 caused a maximum CO2 level of 725 ppm; showing the level recommended by Swedish regulations was high with respect to CO2 level. In addition, measurements showed that the RH and temperature were within acceptable ranges in all cases. An energy savings calculation showed that, in case II, the comparative savings of the combined energy requirement for ventilation fan and ventilation heating were 43% compared with case III.