Effect of mechanical ventilation and natural ventilation on indoor climates in Urumqi residential buildings

Residential buildings are ventilated naturally and mechanically. Both ventilation methods provide a healthier indoor environment by introducing external fresh air into the indoor air. The fresh air that enters a room can affect the indoor climate, for example, by reducing the indoor temperature and humidity in the winter. The objective of this study was to research the effects of mechanical ventilation and natural ventilation on indoor climates. Nine homes were selected for a one-year test in Urumqi, China, where the winter weather is severely cold. Four of the residences had natural ventilation, four of the residences had mechanical ventilation with heat recovery, and one residence had mechanical ventilation without heat recovery. The results showed that the indoor climate in Urumqi was dry in the winter and comfortable during the other seasons. Operating a mechanical ventilation system in winter reduced the indoor temperature by 1.6 K and humidity by 3% on average. It also greatly reduced the rate of indoor carbon dioxide, exceeding the standard and making it easier for residents to sense dryness and more likely to humidify their space. Natural ventilation in a room resulted in a little better relative humidity but poorer ventilation. Humidification is necessary for both mechanical and natural ventilation.