Determining IAQ dynamic response to emissions.

To achieve acceptable indoor air quality (IAQ), ASHRAE Standard 62-1989 recommends the use of the alternative IAQ procedure. The IAQ procedure can treat both constant-volume and variable-air-volume (VAV) with constant or proportional outside airflow rates. The relationships in Appendix E of the standard must be used in conjunction with the IAQ procedure to directly calculate indoor air contaminant concentrations in an occupied space. However, these relationships may not provide sufficient information to fully analyze system operation at part-load conditions, and particularly, to predict dynamic variations of contaminant concentrations during the day. Determination of indoor air contaminant concentrations vs. time of the day can be used as a design strategy to provide IAQ compliance in new construction and remodeling as well as a means to monitor whether maximum allowable concentrations are reached in old buildings. This paper will first demonstrate the development of a dynamic model for each of the seven heating, ventilating and air-conditioning (HVAC) systems listed in the standard, and will apply this dynamic modeling to estimate the concentrations of formaldehyde and particulates (PM10) as a function of time in an office occupancy for three types of filters.