Guide to Home Ventilation

Posted 11 May 2018

Guide to Home Ventilation

Ventilation refers to the exchange of indoor and outdoor air. Without proper ventilation, an otherwise insulated and airtight house will seal in harmful pollutants, such as carbon monoxide, and moisture that can damage a house.

 Why Ventilate?

Gases from combustion appliances, like stoves and fireplaces, can ac­cumulate in a poorly ventilated home and threaten your health and safety. Excessive moisture in the home can also threaten your health, and can lead to mould growth, ruin insulation, and even cause structural damage. Additionally, elevated levels of hu­midity can make cooling equipment work harder, leading to more costly energy bills.


 Ventilating a home combines the physical aspects of the house with techniques you can complete after the construction phase. Ductwork and exhaust fans can remove combustion gases from a home. Additionally, there are many ways you can prevent moisture from entering and accumu­lating in your home.


  1. 1.    Natural ventilation is uncon­trolled air movement from windows, doors, or cracks in the home. This used to be the most common ventilation method of allowing fresh outdoor air to replace indoor air in a home, and still is found in older homes.


  1. 2.     Spot ventilation controls air movement by using localized exhaust fans to quickly remove pollutants and moisture at the source. Common household examples include range hoods over stoves and bathroom exhaust fans. Spot ventilation is typically used in conjunction with one of the other strategies, and can be used to improve the effectiveness of natural ventila­tion. If both spot and natural ventilation together do not meet your home’s ventilation needs, then you should consider a whole-house ventilation strategy.



  1. 3.       Whole-house ventilation entails using one or more fans and duct systems to exhaust stale air and/or supply fresh air into the house. Whole-house ventilation systems provide controlled, uniform ventilation throughout the house. They may be exhaust-only (relying on leakage into the building for fresh air), supply-only (relying on air leakage from the building to exhaust stale air), or balanced systems that include both exhaust and fresh air intake components.




Avoiding Moisture Problems Means Good Ventilation


When moist air encounters a colder surface, some of the moisture will condense and become a liquid. This happens on the surface of an iced tea glass, which is why you need a coaster to avoid water damage to a wooden table. In a similar way, moisture condensing inside a wall or in the attic can lead to wood rot and permit the growth of mould. To avoid moisture problems and ensure good ventilation, follow these steps:


  1. Kitchen and bathroom vents should lead directly outside and should never be vented into the attic, where moisture can cause serious problems and pose potential health problems.
  2. Consider adding controlled ventilation after you air seal. It may be necessary to provide fresh air to avoid build-up
  3.  of stale air and indoor air pollutants. Special air-to-air heat exchangers, or heat-recovery ventilators, can do this.
  4. Replace unused, noisy vent fans with quiet ENERGY STAR® models.


Have a moisture escape path

A dehumidifier can effectively reduce moisture levels (though it will increase your energy use).

A humidifier can provide comfort during the winter months, but use it only in rooms that have sufficient air flow to ventilate the room properly and prevent moisture issues.


No winter lasts forever; no spring skips its turn.

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