Healthy Homes

The Problem: Warm, moist air entering the vented crawlspace condenses on cool surfaces, resulting in moisture accumulation. Moisture in turn can attract pests, allergens, and mold, as well as increase the potential for damage to the home and structural components.

Results from the National Survey of Lead and Allergens in Housing suggest that the construction and operation of a house might have a significant influence on the level of allergens. For example, the strongest predictors for dust mite allergen were indoor humidity and age of the home.

In collaboration with researchers at Advanced Energy, a non-profit company that designs and builds energy-efficient components for homes, we have designed and implemented a study that is investigating whether construction techniques can effect levels of indoor allergens and air pollutants.

Being tested is a construction system known as SystemVision Plus which was developed by the building science team at Advanced Energy.

Properly closed crawlspaces are more energy efficient and substantially drier than conventionally built, code compliant vented crawlspaces. By treating the crawlspace more like a conditioned space, moisture is less likely to accumulate, thus reducing the likelihood of moisture related problems often seen in homes built on crawlspaces.

This system was designed to reduce relative humidity, improve temperature control, and reduce particles in indoor air.

This study examines whether we can detect a difference in the environments of the 16 control houses and 20 intervention houses over the course of 18 months. The follow-up of homes will be completed in June of 2006.

The following indicators will be monitored to determine differences between the intervention and non-intervention homes:

• Temperature
• Relative Humidity
• Allergens (endotoxin, mold spore, dust mites, etc.)
• Particulates
• Volatile organic compounds