4 Easy Ways to Manage the Stack Effect

The stack effect is a term used to describe the way air circulates throughout your home, particularly during extreme weather. During the summer, the humid air outside makes its way inside the foundation. Hot air is lighter than cold air, so the air in your foundation rises into your home. It’s because of the stack effect that 50% of the air you breathe in your home comes from your foundation. During the winter, something similar happens.

Because of air buoyancy, the hot air in your home rises and has trouble circulating through your home because of the dense, cold air that is flowing from the foundation. Your floors remain cold while all the warm air from your HVAC system escapes through the attic or chimney. The stack effect influences many aspects of your day-to-day life, such as your energy consumption during winter and summer. Because of the invading air, your HVAC and AC have to work harder, thus consuming more energy than it needs to. Waterproofing and encapsulating your foundation gets rid of this problem and lowers your energy bills considerably.

The stack effect can also contribute to a health hazard. If there is any mold in your basement, the spores will be brought up into your home as the warm air rises. Mold spores can trigger allergies and cause eye, skin, throat, and nose irritation. Long-term exposure to mold can lead to permanent problems with your respiratory system, so waterproofing your foundation should be a priority. If you control the humidity in your foundation, you’ll be able to control the air circulation a lot better.

It’s recommended to regularly check your basement, especially after heavy rainfalls or during seasons with increased precipitation. Monthly checks can help you spot early signs of water intrusion, allowing for timely intervention. 

Before delving into the reasons for the stack effect or the ways in which it can impact you, there’s a simple question to ask first. What is the stack effect in the first place? Here’s a brief primer on what the stack effect is and how it might impact you.

Entrances and Exits

The first thing the stack effect needs is an entrance and an exit. The stack effect happens where there’s an entrance for air in the crawl space or basement and an exit for air in the attic. Almost all attics have an exit for air of some kind, even if it takes a bit of time for it to go through the pathway. That means the problem usually rests with crawl space vents.

When you have an entrance and an exit for air, you’re usually going to end up with the stack effect. This can even be a problem in one-story homes, where the air doesn’t have to travel very much. These entrances and exits are an important part of the stack effect and removing them typically helps.

Warm Air Rises

The second important thing that drives the stack effect is the fact that warm air rises and cool air sinks. This is true regardless of the temperatures of the air; it will automatically rearrange itself so that the warmest air goes to the top and the coolest air goes to the bottom. If the cool air is on top of the warm air, the warm air will move upward through space.

When air enters the crawl space through crawl space vents, it’s either going to be cooler than the surrounding air or warmer than the surrounding air, depending on the weather. If it’s cooler, it will stay in the crawl space for some time, then warm up, rising through the living area and exiting through the attic. If it’s warmer, it will start to rise through the living area as soon as it enters the home.

Tiny Airborne Particles

What’s the big deal with the stack effect? Aside from the fact that it brings in air from the outside, which might include all manner of things, it’s important to note that it’s not just air that’s coming up through the home. The air might include tiny airborne particles it picked up from whatever’s happening in your home’s crawl space.

Many types of particles can become airborne. Mold spores, dirt, dust mites, pest droppings, and many other types of particles are small enough for the air to pick them up. When that air sweeps through your home, those airborne particles are also sweeping through your home, spreading them across your living space. More than 50 percent of the air you’re breathing in your home comes from the crawl space, so whatever is in this area under your house also is in the air circulating throughout the rest of your home and affecting you.