Applicability Improvement of Demand-Controlled Ventilation under an Occupant-Based Ventilation Standard in China

Indoor air quality (IAQ) and energy consumption are becoming increasingly important in the HVAC field. This paper examines the potential of improving demand-controlled ventilation (DCV) performed under an occupant based ventilation standard. CO2-based DCV and radio frequency identification–based DCV methods are simulated in an office building model served by a dedicated outdoor air system combined with a fan-coil system. A numerical model for estimating real-time occupancy is developed. Simulations are conducted with current Chinese ventilation standard as an example. Results show that the current standard causes severe fluctuations under a CO2-based DCV strategy. It is concluded that the current standard defines the ventilation rate as a function only related to the occupancy number, which makes DCV control unstable. As an improvement, the current Chinese ventilation standard is modified to a form similar to the standard of the American Society of Heating, Refrigerating and Air-Conditioning Engineers that considers the occupant and the building separately. The modified standard is applicable to various DCV approaches and can maintain an acceptable formaldehyde concentration. This modification significantly improves the applicability of the current Chinese ventilation standard to CO2-based DCV and can be easily extended to similar ventilation standards.