For many homeowners, leaving the windows ajar solves their indoor air quality concerns. Doing so brings in a draft of fresh air, letting all indoor pollutants escape. Unfortunately, this is not as effective as people think.
Open windows sometimes introduce new pollutants and allergens into the home. Windows lack the purification mechanics used to mediate the exchange of air. But even if the outdoor air blew in clean, there are other insufficiencies that make it unreliable at improving indoor air quality.
Loss of Heating and Cooling
In the summer and winter months, opening the windows can be costly. If you spend money on heating and cooling, then cracking the windows will let that generated warmth and coolness out.
Air Flow
To create an effective air exchange with open windows, you need to create a cross-breeze. This involves opening several windows—preferably on separate sides of the home. With only a single window, the warm air moves in through the top and cycles cold air out the bottom, benefiting only spaces close to that window. A cross-breeze extends the reach of this exchange; however, the air flow pattern created is somewhat linear. Consequently, much of the stale air stays in the home.
Ozone Generation
For lasting improvements to indoor air quality, you need activated oxygen, called ozone. Ozone purifies lingering chemicals and odours, but it only lasts between five and 20 minutes. Even a strong inbound breeze cannot generate sufficient ozone to serve as a sustainable solution. Air exchangers, on the other hand, work constantly to produce ozone, creating an ever-fresh indoor environment.
