Investigation of temperature regulation effects on indoor thermal comfort, air quality, and energy savings toward green residential buildings

To create healthy indoor environments, Chinese green building evaluation standards recommend monitoring and control of CO2 concentration in residential buildings. Regulations of building airtightness levels and indoor temperature will improve thermal comfort and energy efficiency. However, indoor air quality (IAQ; e.g., CO2 concentration) may suffer, which adversely affects indoor occupants' health and productivity. To counteract these negative effects, this work investigated indoor temperature regulation effects on IAQ and energy consumption considering a well-insulated full-scale room with a top-wall-mounted ventilation heating system. First, a series of experiments were conducted with five indoor temperatures (in winter) and constant CO2 sources. Next, corresponding simulations were carried out (air changes per hour, ACHs equal to 4 and 12). It was found that the higher the supplied air temperature, the stronger the negative effects of thermal buoyancy, leading to weaker turbulent diffusion and higher levels of indoor CO2 concentration. A 1 degrees C increase would cause around 1.2% increase of CO2 concentration along with 8.3% more energy consumption. Moreover, the influence of indoor temperature on CO2 dispersion is more significant when ACH is relatively small. Relevant findings will further facilitate the design and regulation of green buildings in the perspectives of indoor heath and energy efficiency.