Controlling the Indoor Environment

People spend nearly 90% of their time inside buildings. This makes the quality of the indoor environment an important pursuit and a significant component of building code. Numerous pollutants exist within homes that can negatively impact indoor air quality and occupant health; proper ventilation is necessary to help diffuse and remove these pollutants.

Some of the most common pollutants are the building and finishing materials used in construction. Many builders are doing a good job of limiting the use of products that contain volatile organic compounds (VOCs). VOC’s are carbon-based compounds that have been used in the construction or chemical composition of many building material products like compressed wood cabinets, paints, glues, adhesives, and carpets. These VOC’s can evaporate and “off gas” as part of the natural part of aging and curing in new homes.

In addition to VOCs, building pollutants occur from occupant use and behavior. Of critical concern is the potential for carbon monoxide. Garage and combustion appliances are the main sources of carbon monoxide (CO) in homes. In order to control the source of this odorless, toxic gas, unvented combustion is prohibited in all current building codes and directly vented appliances are highly recommended. Weather stripping the attached garage door and installing an air barrier to the garage walls attached to the house can help keep CO from entering the house through cracks and penetrations. With the release of ASHRAE 62.2-2013, CO alarms are now mandatory for all residential dwellings.

Cleaning products are another pollution source common in homes and buildings. The combination of bleach-based cleaners, aerosol disinfectants, and indoor pesticides can create a toxic cocktail found underneath many kitchen sinks. As homes become tighter and tighter to improve energy efficiency and reduce the infiltration of outdoor conditions, mechanical ventilation is increasingly necessary.

Furthermore, education is needed to inform homeowners about indoor pollutants to promote source control strategies. Some above-code programs already honor measures that reduce chances of bringing outdoor pollutants, like pollen and dirt, into the house. They offer credits for utilizing walk-off mats at entrances and keeping shoes racks a certain distance from the living space. Additionally, many green building programs emphasize the use of low VOC products and the use of green cleaning products. When coupled with proper ventilation, source control goes a long way in better indoor air quality.