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What Is House Ventilation And Why Is It Important?

Morgan McBride5-Minute Read
April 02, 2021

House ventilation is an important system within any modern home. New construction is designed to be air-tight, meaning that the air within it will grow stale from being breathed in and out as well as from internal contaminants. A ventilation system brings fresh, new air indoors and removes old, stale air. Adding the right one is essential for any construction project.

What Is House Ventilation?

House ventilation refers to the movement of air between the inside and outside of the house. Whole house ventilation is, for many, an important part of having a healthy home. Modern homes are so tightly built that air doesn’t move as freely through cracks in the walls as it does in older homes, so homeowners may choose one of four types of ventilation systems: an exhaust, supply, balanced or energy recovery/heat recovery (ER/HR) ventilators.

Why Does Ventilation Matter?

There are several health concerns that motivate homeowners to consider house ventilation. Allergens, pollution from modern building materials and air pollutants from outdoors can cause discomfort and illness. Proper ventilation is important to ensure that those pollutants do not enter your home and cause short- or long-term health problems.

Old Vs. Newer Homes

There are differences between old homes and newer homes in terms of air exchange. Old houses are known to be “drafty.” That draftiness is because air was able to flow in between small gaps in the construction of the home. Modern homes have batt insulation and caulk tubes, as well as other precautions that prevent air flow from outside to inside the home.

Types Of Whole House Ventilation Systems

There are four types of ventilation systems: exhaust, supply, balanced and ER/HR. Note that homeowners in warmer climates might have different needs from those in colder climates.


You might have heard of an exhaust fan. Exhaust systems use these fans in pollutant-creating areas like kitchens, bathrooms, basements, or attics to blow polluted air out. New, fresh air comes in through intentional “passive vents” or leaks in the walls.

Because the external air comes in through passive vents, humid climates can lead to moisture getting into those cracks and crevices, which can lead to mold you’ll need to remove down the line. So, this method is not recommended for humid areas.

Also, since air is just coming in little cracks, it can bring in pollutants like radon, mold, dust, pollen, or really anything floating around outside. This system also doesn’t alter the temperature or humidity of air coming in these small cracks, which means your heating and cooling system will have to work harder to get that new external air to the proper temperature.


Supply systems are basically the reverse of exhaust systems. They use a fan to blow new fresh external air into a building. It then leaks old air out small cracks or “passive vents” in your home.

Using a fan to blow new air in helps to control the flow of incoming air. You can better filter out pollutants, pollen and dust by adding filters to the fan and you can adjust the humidity of air coming in. This will help to reduce heating and cooling costs compared to an exhaust system.

Supply systems don’t work great in cold climates. As warm, heated air slowly leaks out of a home into the cold exterior, this change in temperature and humidity can cause moisture to condense, especially in attics. This warm moisture can lead to mold and rot.


A balanced ventilation system is a combination of exhaust and supply systems with two fans and two systems of ducts. It exhausts air from rooms that cause more pollutants – like kitchens and bathrooms – and also blows fresh air into rooms like living rooms and bedrooms. These systems filter out pollutants at the ventilated point of entry.

Because of the dual fan system, balanced ventilation works well for all climates. However, they are twice as expensive to install and operate since they are basically two systems.

ER/HR Ventilators

Energy recovery systems are designed to be as energy efficient as possible. These systems use heat exchangers to transfer heat in a way to maintain constant internal temperatures and reduce the need for heating and cooling as much as possible. Basically, they capture the temperature of old air as it is blown out of the building and transfer that temperature to the new air as it is blown in.

Heat recovery ventilators transfer heat from inside to outside the home to keep the temperature balanced. ER ventilators transfer heat as well as moisture. This makes ER ventilators better for humid climates.

These complex systems are the most expensive to install and maintain. They require a lot of technical expertise that might be difficult to find in some areas.

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Are The Energy Costs Worth The Benefits Of House Ventilation?

The houses that need ventilation systems the most are newer, more airtight buildings. These buildings tend to be much more energy-efficient than the older homes that don’t need ventilation. The appliances involved are themselves energy-efficient, which means that installing a ventilation system will enhance health while still allowing building owners to reduce their carbon footprint.

Is House Ventilation Synonymous With Air Purification?

There are major differences between ventilation and air purification. Air purification filters air and removes contaminants from it. On the other hand, air ventilation is simply the distribution of fresh air to the various rooms of a home. Ventilation helps to find a balance in air quality, temperature, and humidity and keeps air from going stale. However, if external air is very polluted or contaminated, ventilation will not remove those pollutants – only purification can do that.

The Bottom Line: Tight Homes Need A Breath Of Fresh Air

Modern homes are airtight – which is great for many reasons. However, it does mean that you need to be on top of your home’s ventilation system to ensure the health of your home and those who live in it. Want to learn more? Check out our resources to learn more tips about homeownership.

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    Morgan McBride

    Morgan McBride is a DIY-lover and home decor enthusiast living in Charleston, South Carolina. She has been blogging at CharlestonCrafted.com alongside her husband since 2012, where they empower their readers to craft their current home into their dream home through the power of DIY.