Advance time for HVAC system operation based on volatile organic compound distribution emitted from building materials

When people are entering the indoor environment, acceptable perceived indoor air quality or temperature could be achieved by turning on the HVAC system in advance. By adopting the concept of accessibility of contaminant source and employing the CFD method, studies the time for the pollutant concentration to reach steady-state and the corresponding advance time for HVAC system operation based on pollution (volatile organic compound, VOC) distribution emitted from building materials under the isothermal and non-isothermal ventilation conditions, respectively. The results show that the time for the distribution of the pollution emitted from building materials to reach steady-state could be between 6 h and 16 h for eight typical ventilation scenarios under isothermal condition when the air change rate is set to 1 h^-1. The advance time for HVAC system operation could be determined by the time for the pollutant concentration to reach steady-state under the non-isothermal ventilation condition. At the higher air change rates (≥ 4 h^-1), the time for the indoor average temperature to reach steady-state could be close to the time for average VOC concentration near breathing area to reach steady-state, which is from 1 h to 3 h. Therefore, the advance time could still be determined by the time for the indoor temperature to reach steady-state in practice.