Whole-house ventilation is the process of supplying fresh air to a living space and exhausting stale air, either by natural or mechanical means in order to maintain an acceptable level of air quality. Normal human activities such as cooking, bathing, breathing, and maintaining houseplants introduce indoor pollutants (including excessive levels of water vapor) into the home. Additionally, building materials and furnishings can contribute to indoor pollution through the out-gassing of chemicals used in their manufacture.

Ventilation either dilutes pollutants (including excessive levels of humidity) or flushes them from the home. Residential construction traditionally has relied on infiltration to provide ventilation. Infiltration is the leakage of air through the building envelope through unintended gaps in walls, roofs, windows, doors and other construction elements. Improvements in construction, however, have resulted in more airtight buildings and hence the need for dedicated mechanical or passive devices to satisfy ventilation needs. Furthermore, infiltration has been shown to vary with environmental conditions such as wind and temperature differentials, and for significant periods these driving forces may not be sufficient to achieve adequate natural infiltration.

The purpose of this research was to provide a baseline for evaluating whole house ventilation strategies for manufactured homes. The report identifies research that needs to be done in the future to update the foundation upon which recommendations to the ventilation standards for HUD code homes are made and guide the industry towards improved, more efficient, and cost-effective practices to achieve the desired ventilation level.