Your Homes Ventilation System
To provide good air quality, enough air needs to be brought in and circulated so that it reaches all areas of the home. For almost all homes, windows and structural elements contribute to bringing in fresh air. Many homes have additional mechanical systems to add to the flow. Some sources, such as stoves and bathrooms, need special venting that can remove the pollution they produce. Ventilation above stoves needs to carry the air outside to avoid redistributing pollutants from cooking inside the home. Good ventilation practices vary depending on what type of climate you live in. This article is based on homes constructed in Wasaga Beach Ontario.
Ventilation is describes as the conscious introduction of outside air into a closed space and its circulation. Ventilation is used to manage the quality of air inside the closed space by dispersing the pollutants through the dilution of indoor air.
Purpose of Good Ventilation
Proper ventilation can help remove moisture, smoke, cooking odours, and indoor pollutants from your home. Structural ventilation controls heat levels in the attic, moderates dampness in the crawlspace and basement, and keeps moisture out of uninsulated walls. It is also good to have an airflow that is uninterrupted, as anything blocking the air flow in your home can cause damage to both your home and your health. One of the reasons ventilation is so important is because it controls how much moisture is lingering in your home. Without a ventilation system in place, you have no control of the air flow in a building.
Effects of Poor Ventilation
Pressure Differences
Neagative Air Pressure
Negative air pressure in a home in summer will draw warm air in and increase either your cooling costs or your discomfort. There is also a minor durability concern that warm, humid outside air may cause condensation when it arrives at a cool surface on the interior of your wall assembly, like your vapour barrier. The greater the differential in temperature between inside and out, the greater the concern. Cold air will be drawn into home in winter and hot air drawn in during summer.
Positive Air Pressure
Positive air pressure in houses in winter is the biggest problem. The difference between indoor and outdoor temperature is so extreme in winter that positive pressure will force warm, humid air from inside your house out
through the tiniest of openings in your walls where it can condense and deposit moisture causing mold and wood rot deep in the structure.
The Stack Effect
The stack (or chimney) effect is the same uphill battle, and unlike wind issues it is happening 24/7. As warm air rises it creates more pressure on upper levels and pushes air out; to compensate, air will be drawn in on lower levels.
Health Issues
Contaminants such as dirt, dust, pet dander, pollen and biological growth can accumulate in homes with inadequate ventilation. These pollutants can cause common asthma or allergy symptoms and other health problems. Air fresheners, cleaners, paints and many other products emit volatile organic compounds such as benzene and acetone. They often lead to dizziness and fatigue. If you feel better when you’re away from home, but your symptoms return when you come back, you should consult a professional about additional ventilation.
Some Common Household Contaiminants found in Wasaga Beach
- Carbon dioxide (CO2) from building occupants and combustion of fuels such as gas and oil furnaces and heaters.
- Carbon mondoxide (CO) – from vehicle exhaust brought into the buidling by air intakes.
- Dust, fibreglass, asbestos, gases, including formaldehyde – from building materials.
- Vapours, volatile organic compounds (VOCs) – from copying and printing machines, computers, carpets, furnishings, cleansers and disinfectants, solvents, pesticides, disinfectants, glues, caulking, paints etc.
- Dust mites – from carpets, fabric, foam chair cushions.
- Microbial contaminants, fungi, moulds, bacteria – from damp areas, wet or damp materials, stagnant water, condensate drain pans, etc.
- Ozone – from photocopiers, electric motors, electrostatic air cleaners.
- Other sources: tobacco smoke, perfume, body odour, food, etc.
HRV Heat Recovery Ventilators
A heat recovery ventilator (HRV) is a ventilation device that helps make your home healthier, cleaner, and more comfortable by continuously replacing stale indoor air with fresh outdoor air. New homes built since 1977 are more airtight, which helps save energy but can make the inside air stale. To complement this airtightness, modern homes use HRVs to distribute fresh air throughout the house.
The ‘efficiency rate’ of an HRV unit determines how much energy will be saved by using that particular device. Although it requires the operation of a fan on a continual basis, the energy recovered from the inside air is many times that of the energy required for the fan. ( As of January 1, 2017, the Ontario Building Code (OBC) SB-12 has been revised to require heat recovery ventilation or ventilators (HRV) in all new homes. )
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.
Contact the Wasaga Beach Home Inspector for more information on your Homes Ventilation Systems.