Passive Ventilation

To get the best indoor air quality, you could combine passive ventilation with mechanical ventilation solutions installed throughout the home for better economy and function.

Today's homes are designed to be energy-efficient and airtight. However, many suffer from poor indoor air quality.

Ventilation is essential for maintaining healthy air. Indoor air can become polluted by allergens, odors, humidity, and use of the bathroom and kitchen.

Carpeting and furniture can also off-gas volatile organic compounds. Ventilation removes humid, polluted indoor air and replaces it by fresher, more humid outdoor air.

Two Types of Ventilation

passive ventilationMechanical ventilation and passive ventilation are two options to remove polluted air or introduce fresh air.

Mechanical ventilation is the most common method. This includes exhaust fans in bathrooms, kitchens, laundry rooms, and attics as required by local building codes.

Passive ventilation is a better alternative to mechanical ventilation.

What is Passive Ventilation?

Passive ventilation uses a series vents on exterior walls and exterior windows to let outside air enter the home in controlled ways.

The natural airflow, wind, and temperature differences between indoor and outdoor air allow fresh air to enter the home and circulate through it.

Fresh air pulls polluted, humid and warmer air into vertical conduits (aka thermal chimneys), which lead to the attic. From there, the air is exhausted to outside.

Fresh-air vents are designed to disperse indoor air and slow down the incoming air. A precision damper inside the vent regulates airflow.

Vents often have a filter to keep out insects and dust. A few fresh-air vents have acoustical components that can mask outside noises, such as trains and traffic.

Benefits and Drawbacks (Pros and Cons)

Passive ventilation does not require electricity, unlike mechanical solutions such as extractor fans and air purifiers. This saves energy and reduces carbon monoxide emissions.

Because it doesn't require moving parts, this hands-off form of ventilation is quiet, cost-effective, efficient and low-maintenance. In fact, the only maintenance that is required after installation is periodic cleaning of filters.

Passive ventilation is very dependent on outside temperature. It works best in colder months when there is a greater difference between indoor and outdoor temperatures.

Passive ventilation alone cannot remove humidity from bathrooms or laundry rooms, unlike auto-evaporating air conditioners or dehumidifiers would. It should always be used with a heat recovery unit.

Locating Vents

The areas where fresh-air vents are most likely to be found should include bedrooms, living rooms and offices.

Do not install fresh-air vents in bathrooms, kitchens, or other wet areas of your home. These areas are the best places for exhaust vents as polluted air is more likely in these areas.

Consider all the livable space in a single unit when calculating how many fresh-air vents are needed to ventilate a home. To find out how many square feet each vent can serve, read the specifications from the manufacturer.

Next, calculate how large the living space is and decide how many vents you need. If a vent can service 100 square feet, you will need 20 vents to cover 2,000 square feet.


By including the passive type of ventilation in your home to provide cleaner air and better air quality overall, you will save money on future electricity bills over mechanical venting methods.

This can represent a low carbon footprint, zero emission solution to having clean air inside the home for better health and peace of mind for you and your family.