Study on the Effect of an Intermittent Ventilation Strategy on Controlling Formaldehyde Concentrations in Office Rooms

Abstract

Material emission and ventilation are two aspects influencing indoor air quality. In this study, a model predictive control (MPC) strategy is proposed for intermittent ventilation system in office buildings, to achieve a healthy indoor environment. The strategy is based on a dynamic model for predicting emissions of volatile organic compounds (VOCs) from materials. The key parameters of formaldehyde from panel furniture in the model are obtained by an improved C-history method and large-scale chamber experiments. The effectiveness of the determined key parameters is validated, which are then used to predict the formaldehyde concentration variation and the pre-ventilation time in a typical office room. In addition, the influence of some main factors (i.e., vacant time, loading ratio, air change rate) on the pre-ventilation time is analyzed. Results indicate that the pre-ventilation time of the intermittent ventilation system ranges from several minutes to several hours. The pre-ventilation time decreases exponentially with the increase in the vacant time, the air change rate, and with the decrease in the loading ratio. When the loading ratio of the furniture is 0.30 m2/m3 and the vacant time is 100 days, the required pre-ventilation time approaches zero. Results further reveal that an air change rate of 2 h−1 is the most effective means for rapid removal of indoor formaldehyde for the cases studied. The proposed strategy should be helpful for achieving effective indoor pollution control.

Tempo-spatial infection risk assessment of airborne virus via CO2 concentration field monitoring in built environment

“…In order to reduce the deviation, and most importantly, to cope with the virus-laden aerosol accumulation problem, it is highly recommended to regularly vacant the occupied rooms and replace the contaminated indoor air with fresh air through thorough natural ventilation, preferably several times throughout the day. This intermittent ventilation strategy has been proved effective in formaldehyde concentration controlling in offices [ 46 ]. In addition, personalized ventilation may be applied to remove the viral aerosols when spatial infection risks were assessed to be high [ 47 ].…”