HI-02-09-1 -- Multizone Modeling Approaches to Contaminant-Based Design PDF

Indoor air quality is currently addressed in the design process primarily through prescriptive building codes based on specified flow rates. However, a contaminant-based design approach opens the door to design innovation, offering opportunities for improved indoor air quality, energy conservation, and reduced environmental impact. This paper discusses current design approaches and some possibilities for the future of contaminant-based design. Techniques and modeling approaches that could be used today are demonstrated using examples from a case study building. A multizone network airflow model is used to simulate airflow rates, pressure relationships, and contaminant transport. These simulations are utilized to specify minimum ventilation rates to control non- occupant-related contaminants for a system with carbon dioxide demand control. Contaminant buildup during an overnight shutdown is also studied,and strategies for a pre-occupancy purge are developed. The model is also used to size an exhaust fan to negatively pressurize an enclosure housing a biological process. The design is then re-evaluated based on experimental measurements of envelope airtightness and contaminant emissions that were conducted in the building. The case study identifies the critical, or “design,” conditions that must be addressed, discusses strategies that could be used to meet them with contaminant-based design, and considers the role that available measurements can take.

Units: SI