Don't leave your home ventilation to the weather
A home without a well-designed ventilation system is at the mercy of the weather. In such a building the air exchange or "breathing rate" through unplanned openings like cracks and windows is governed by the weather and the building's height.
The largest volumes of air move in and out of a house when the wind is blowing and the difference between inside and outside temperatures is the greatest. In a taller building like an apartment complex or multi-story home, air moves in and out at a much high rate than in a single story dwelling.
Also, unplanned openings can also bring more polluted air into a building from undesirable locations, such as dusty or rodent-infested attics, moist crawlspaces, or attached garages where gasoline, fuel bottles, and pesticides are stored.
Relying on unintentional ventilation means the house may be under-ventilated and over-ventilated during the changing seasons.
During cold weather, the low temperatures and wind lead to maximum air exchange rates, causing uncomfortable drafts and increased heating bills as the cold air rushes in.
On hot days, when the AC is working overtime and outside temperatures on the rise, unintentional ventilation draws into the home the hot, outdoor air that must be cooled, increasing cooling costs.
Most climates have shoulder seasons, when indoor and outdoor temperatures are similar and heating and cooling loads may be smaller. During mild weather with little wind, little air moves naturally in and out of a home. That leads to rising levels of indoor pollutants and inside air can become stuffy, stagnant, moisture-laden, and unhealthy.
Intentional, well-designed ventilation overcomes these problems. Whether you have a whole house ventilation or adequate spot ventilation, good fans can tackle indoor air quality problems. Your home will feel better, smell better, and use less energy.