Mechanical ventilation has a key role in modern construction, by providing fresh air to air-tight homes. But mechanical ventilation can also be crucial to exhaust stale air, or to prevent moisture, mold and mildew...
Uncontrolled ventilation can be a cause of high energy bills, unhealthy air and moisture damage.
Every home should have high-quality exhaust fan in each kitchen and bathroom.
Many people still think that their houses need to “breathe”, which makes little sense and contradicts modern construction, with their high levels of air tightness and insulation.
Mechanical ventilation systems vary in their type and complexity, and can be grouped into three classes: exhaust, supply and balanced mechanical ventilation systems.
Air infiltration through gaps and openings in the walls, floors and ceilings, or around windows and doors, is the main source of fresh air in many homes.
But air infiltration is a questionable source of fresh air. Air coming in from attics, crawlspaces or wall cavities carries dust, pollutants, moisture, radon... Mechanical ventilation can solve the problem.
Spot kitchen and bathroom ventilation is very important to prevent moisture damages, mildew and mold; every home should have high quality exhaust fans ducted to the outdoors.
Spot exhaust fans should be properly ducted to the outdoors; exhaust air should not be vented into the attic or any other close space.
Roof ventilation can help keep attic temperatures lower. Just do not overestimate it, and do not increase attic ventilation beyond the necessary.
Attic fans - either electric or solar - are popular, but typically ineffective and in some cases counterproductive. They may consume more energy than they save. There are better ways of dealing with overheated attics.
Consider mechanical ventilation and air movement as a way of controlling moisture; it's important to keep your home's moisture levels low, especially in the winter.
Moisture control is important to keep indoor air healthy and to avoid structural damages in walls, floors or attics.
See: Home Moisture Guide
Natural ventilation and shading strategies are the backbone of natural cooling.
Ventilation fans are intended to bring breezes in, during the cooler parts of the day.
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