Keeping Our Homes Healthy with Proper Ventilation
January is Radon Awareness Month. Although radon is probably the most popular indoor air contaminant, there are others we should be aware of. Particulates from mold, dust, dander, and pollen as well as volatile organic compounds (VOCs) and combustion gasses are often found inside our homes. Exposure to indoor air contaminants is inevitable, but proper ventilation can help reduce our exposure and help homeowners in Nashville, TN create healthier homes.
It doesn't matter if your home is old or new, ventilation is important for keeping the air in the house clean. When it comes to proper ventilation, there are several strategies for achieving the right type and amount of fresh out door air.
Exhaust-only: This is the most common approach in existing homes, The exhaust-only method uses bathroom and kitchen fans to suck odors and moisture out of the house in these localized area. The make-up air that replaces the exhaust air is pulled in by natural pressure changes through cracks, gaps, and wholes in the building shell. The air that enters the home is unfiltered and unconditioned. For this reason, exhaust-only is generally not recommended.
Supply-only: The supply-only method is typically achieved in this climate zone using a ventilating dehumidifier, which supplies the house with a certain amount of dehumidified outdoor air. Often times this air supply is ducted into the HVAC's duct system for further conditioning and/or mixing before it is introduced into the house. This strategy is a great approach for existing homes that have had some air sealing done to improve energy efficiency.
Balanced System: A balanced system means that the same amount of air volume that is being exhausted from the home is also being supplied by outdoor air. In this climate, an energy recovery ventilator (ERV) is used to achieve this. The fresh outdoor air being supplied by the ERV is filtered and pre-conditioned with the exhaust air from the house in a heat exchanger located in the center of the ERV. ERV's are the best option for efficient homes with low air leakage rates (aka "tight houses"), such as passive houses.
With the newly adopted building codes in Davidson County, new homes are now required for the first time to be equipped with either a supply-only or a balanced mechanical ventilation system. Exhaust only is also an option, but not recommended for humid climate regions, such as Tennessee. These systems are now required because of the new requirements for air tightness, which helps make a home more efficient. This is a good thing for energy savings as well as indoor air quality!
If you have questions about the air quality in your house and are interested in learning how to create a healthier home, give us a call and ask to speak to one of our building scientists about the best strategy for your home.