Most home heating and cooling systems, including forced air heating systems, do not mechanically bring fresh air into the house. Opening windows and doors, operating window or attic fans, when the weather permits, or running a window air conditioner with the vent control open increases the outdoor ventilation rate. Local bathroom or kitchen fans that exhaust outdoors remove contaminants directly from the room where the fan is located and increase the outdoor air ventilation rate.
It is particularly important to take as many of these steps as possible while you are involved in short-term activities that can generate elevated levels of pollutants — for example, painting, paint stripping, heating with kerosene heaters, cooking, or engaging in maintenance and hobby activities such as welding, soldering, or sanding. You might also choose to do some of these activities outdoors if you can and if weather permits.
Advanced designs of new homes are starting to feature mechanical systems that bring outdoor air into the home. Some of these designs include energy-efficient heat recovery ventilators (also known as air-to-air heat exchangers).
Ventilation and shading can help control indoor temperatures. Ventilation also helps remove or dilute indoor airborne pollutants coming from indoor sources. This reduces the level of contaminants and improves indoor air quality (IAQ). Carefully evaluate using ventilation to reduce indoor air pollutants where there may be outdoor sources of pollutants, such as smoke or refuse, nearby.
The introduction of outdoor air is one crucial factor in promoting good air quality. Air may enter a home in several different ways, including:
- through natural ventilation, such as through windows and doors
- through mechanical means, such as through outdoor air intakes associated with the heating, ventilation and air conditioning (HVAC) system
- through infiltration, a process by which outdoor air flows into the house through openings, joints and cracks in walls, floors and ceilings, and around windows and doors.
Infiltration occurs in all homes to some extent.
Natural ventilation describes air movement through open windows and doors. If used properly natural ventilation can at times help moderate the indoor air temperature, which may become too hot in homes without air-conditioning systems or when power outages or brownouts limit or make the use of air conditioning impossible.
Natural ventilation can also improve indoor air quality by reducing pollutants that are indoors. Examples of natural ventilation are:
- opening windows and doors
- window shading such as closing the blinds
Most residential forced air-heating systems and air-conditioning systems do not bring outdoor air into the house mechanically, and infiltration and natural ventilation are relied upon to bring outdoor air into the home. Advanced designs for new homes are starting to add a mechanical feature that brings outdoor air into the home through the HVAC system. Some of these designs include energy efficient heat recovery ventilators to mitigate the cost of cooling and heating this air during the summer and winter.
When adding outside air in order to dilute the pollution within your home is not there are a few other options. HEPA air purifiers which are separate from your homes HVAC system can be effective. If this is not an option many newer homes have an air filter cabinet located on top of or underneath the furnace depending on whether it is an upflow or downflow model, putting a charcoal or other type of particulate filter in can help reduce pollutants within the home.