Pozzi Chimney Sweep Blog

What Is The Stack Effect?

Since the mission of Pozzi Chimney Sweep is to make your home as energy efficient as possible, one of the things our technicians will evaluate is the airflow inside your home to make sure there are no leaks that contribute to the stack effect and cause your heating and cooling costs to be higher than necessary.

What is the Stack Effect - Pozzi Chimney - Aurora IL Simply defined, the “stack effect” happens when there is negative air pressure resulting from a difference in temperature and moisture in the air as it flows in and out of homes. When the stack effect occurs in your home, it means you have a wind tunnel blowing the warm (depending on the season) or cool air you want to keep in your home up and out your chimney and undermines your efforts to cost effectively heat or cool your home.

The architecture.com website provides this more technical description, “Stack ventilation is where air is driven through the building by vertical pressure differences developed by thermal buoyancy. The warm air inside the building is less dense than cooler air outside, and thus will try to escape from openings high up in the building envelope; cooler denser air will enter openings lower down. The process will continue if the air entering the building is continuously heated, typically by casual or solar gains.”

The mission of Pozzi Chimney Sweep is to make your home as energy efficient and safe as possible. One of the things our technicians will evaluate is the airflow inside your home to make sure there are no leaks that contribute to the stacking effect and cause your heating and cooling costs to be higher than necessary.
To help further explain the stack effect, Erik North, explains “If you’ve ever seen an eagle or other large bird gliding above a canyon’s warm air flows, then you can understand the stack effect. The eagle is taking advantage of the warm air that flows up between the canyon walls and buoys the bird aloft. A similar effect happens within your home when warm air flows up through the building enclosure. The stack effect is based on buoyancy and encompasses the air either moving into or out of your home.”

So now that you know about the stack effect, what does it really mean to you on a practical basis?

First, if you are experiencing unexplained drafts it may mean that your home is not air tight, which happens a lot in older homes. If you have more than one floor to your home the air pressure will decrease on each floor the higher you go; air pressure on the first floor or in the basement will be higher than on the 2nd or 3rd floor. In the winter, cold air is drawn into your home when your intention is to have a warm home. In the summer, the opposite happens. The air you are paying utility bills to heat or cool is being wasted, drawn outside thru cracks, leaking windows, and the largest openings to the outside, your fireplace and chimney.
Another adverse consequence of the stack effect is that improper ventilation and air flow can be a cause of the offensive smell coming from your chimney.

The most important take-away we want all home owners to know is that you are not expected to fully understand the nuances of thermodynamics and how it is affecting your home. Because we do. That’s why you work with a chimney professional. We are trained to provide the services that can make your home as energy efficient, safe, and comfortable for you as possible. If you live in Northern Illinois, and are feeling drafts in your home, call Pozzi Chimney Sweep, if you don’t live in our service area, we will happily recommend a colleague in your service area.