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Modeling Study of Ventilation in Manufactured Houses



Andrew K. Persily, S R. Martin


The HUD Manufactured Home Construction and Safety Standards (Part 3280, 1994) contain a number of requirements intended to provide adequate levels of outdoor air to the occupants of manufactured homes. In the implementation of these standards, some questions have arisen regarding the impact and significance of some of these requirements. These questions relate to the actual ventilation rates in homes built to the standards and the means of providing supplemental mechanical ventilation to meet the requirements of the standards. Questions have also arisen as to how specific ventilation system components such as duct leakage, local exhaust fans and ventilation inlets affect ventilation rates, air movement patterns, and building pressures. In order to obtain some insight into these issues, the multizone airflow and indoor air quality simulation program CONTAM was applied to a double-wide unit and a number of simulations were performed for several different ventilation approaches. As part of this effort, NIST reviewed the existing literature on ventilation in manufactured homes to identify issues of concern regarding ventilation in these buildings and the impact of the HUD standards. Based on this review, a number of simulations were performed to predict outdoor air ventilation rates into the house due to infiltration and mechanical ventilation, interzone airflow rates between the rooms, and building air pressures relative to the outdoors. Annual simulations were performed in three cities to assess the impact of climate on ventilation rates over a year and the energy impacts of infiltration and ventilation. The results show that despite the assumption in the HUD standards that infiltration contributes 0.25 h-1, the predicted infiltration rates are lower than this value for many hours of the year particularly during mild weather conditions. The supplemental ventilation systems investigated in this study provide ventilation rates that meet the total ventilation requirement of 0.35 h-1, but the impact of such systems is strongly dependent on their operating schedules. The results of these simulations are presented and discussed, and recommendations are made for changes relative to the HUD standards and for future research.
NIST Interagency/Internal Report (NISTIR) - 6455
Report Number


building performance, building technology, manufactured homes, modeling, residential, ventilation


Persily, A. and Martin, S. (2000), Modeling Study of Ventilation in Manufactured Houses, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed April 21, 2024)
Created February 1, 2000, Updated February 19, 2017