The Dirty Details
Many home cleaning products, building materials and furnishings release pollutants and chemicals into your home’s air, including: volatile organic compounds, or VOCs, that are linked to respiratory problems and other health impacts; formaldehyde, which is known to cause cancer; and hormone-disrupting and cancer-causing chemicals from flame retardants, PVC plastics and perfluorinated chemical coatings.
Additionally, insufficient airflow and humidity can create an ideal breeding ground for mold and dust mites, which can cause allergic reactions and exacerbate asthma symptoms.
Appliances like gas stoves, fireplaces or clothing dryers can release gases such as carbon monoxide, which can cause headache and dizziness, or can even be fatal at higher concentrations.
Radon, a naturally occurring radioactive gas that can seep from the ground into basements through foundation cracks, may also be a concern, as exposure is linked to lung cancer. Testing for radon, which is simple and inexpensive, is the only way to know if your home has a problem.
Types of Ventilation
You should use a home ventilation system appropriate for your climate, the humidity level in your home, and the degree to which your home is airtight.
There are three types of ventilation systems used in homes:
- Natural ventilation, which is attained by simply opening windows and doors. It's the easiest, least expensive way to bring in fresh air, but it may not circulate air evenly where you need it most, and it is energy inefficient in extreme weather conditions.
- Spot ventilation, which removes pollutants through exhaust fans in the kitchen or bathroom.
- Whole-house ventilation, which exchanges air uniformly throughout the home, is recommended for well-sealed, energy-efficient homes. While adding a whole-house ventilation system can be expensive, using existing central heating and cooling ductwork can help lower the installation cost.
With any of these options, the placement of the exhaust and/or supply ventilation is critical to ensuring that air is ventilated in all parts of the home’s living space. Pay special attention to bedrooms and bathrooms where dirty and moist air tends to get trapped behind closed doors. A whole house exhaust fan should be centrally located and close to bedrooms –for example, in a hallway or stairwell. Bedroom doors should be kept open during the day, or have space between the bottom of the door and flooring to allow sufficient airflow. Work with a HVAC professional to design and install the appropriate ventilation system for your home and climate.
Each type of whole-home ventilation system has its pros and cons:
- Exhaust ventilation is the least expensive to install and works well in cold climates. Exhaust ventilation uses a fan to push air out of the house through a central outlet. The disadvantage to this type of ventilation is that the fan can potentially draw moisture or pollutants from other parts of the house–like dust from the attic, or mold and radon from a crawl space–into the main living space.
- Supply ventilation is similar to exhaust ventilation, except that the ventilation fan pulls outside air into the home. Fewer pollutants are introduced compared to exhaust ventilation, and the outside air entering the home can also be filtered.
- Balanced ventilation systems are the best of both worlds, using exhaust and supply fans (or vents) to bring fresh air in and push old air out. There is less concern about pulling contaminants inside since fresh air is being drawn from outside—not attics or crawl spaces—and incoming air can be filtered. This system is suitable in all climates, but can be more expensive to install and operate.
- An energy recovery ventilation system may be cost effective in areas with extreme winter or summer temperatures. Transferring the home’s heating or cooling from the exhausted air to the incoming air before it enters the house can recover about 70 to 80 percent of the energy. Although installation of this type of system can be expensive, costs can be minimized by sharing existing duct work.