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Prototype Software for Contaminant-Based Design



George Walton, Andrew K. Persily


Outdoor air intake rates of mechanical ventilation systems have traditionally been determined using prescriptive methods based on ventilation requirements per unit floor area or per occupant. This approach has serious shortcomings. It provides no information on other important system parameters such as filter efficiencies and operating schedules, and it neglects other building design issues such as outdoor air quality and indoor contaminant sources. Nor can it account for the benefits and impacts of non-ventilation based indoor air quality control technologies, such as particle filtration, gaseous air cleaning, system controls, and low-emission materials and furnishings. The inability to account and ultimately take credit for such control technologies could inhibit technological innovation in these areas and potential indoor air quality improvements. In order to move from prescriptive to performance-based indoor air quality design of ventilation systems, and in fact whole buildings, design methodologies are needed that consider contaminant loads and design criteria. This report refers to such design methods as contaminant-based design. This report presents an initial version of software called the Indoor Air Quality Design Tool (IAQDT) that enables contaminant-based design analysis. The tool is based on a number of simplifying assumptions such as a single well-mixed zone, a constant coefficient source model, and constant efficiency filters. However, it does not allow a designer to select building ventilation rates and filtration and air cleaning efficiencies based on contaminant source strengths and contaminant concentration limits.
NIST Interagency/Internal Report (NISTIR) - 6723
Report Number


Design, Indoor Air Quality, Simulation


Walton, G. and Persily, A. (2002), Prototype Software for Contaminant-Based Design, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD (Accessed April 16, 2024)
Created January 2, 2002, Updated February 19, 2017