The same convection force that causes a hot-air balloon to rise can happen in a home. It’s simple science. Hot air rises and cool air sinks. Hot air balloons rise because they’re filled with heated air. When the air inside the balloon starts to cool down and becomes denser, the balloon will start to descend. When this science happens in our home, it can cause energy problems and major comfort issues. In our homes and buildings, it’s known as the Stack Effect. It’s the connection between convection and the energy performance in the home. All homes and buildings leak and this wastes energy.

How Does the Stack Effect Work?

The heating system heats the air inside your home. The air will rise by convection to the upper area of the home. The warm air won’t stop moving when it gets to the top and most homes have hundreds of gaps and cracks that allow areas for this warm air to escape into the attic. These gaps can be holes for recessed lights, gaps around drop-down attic stairways and the cavities in the walls used for plumbing or electrical chases. These are all common areas for theses leaks to occur. This effect occurs all year round but is more noticeable in the cold winter months. In the winter, warm air in a heated building is less dense and lighter than the colder outside air. This forces the warm air to rise up and out. This flow of air will draw cold air into cracks at the bottom. The stack effect ventilation reverses in summer. The hot air outside of an air conditioned house will push cooler indoor air down from the ceiling and out of cracks in the basement. Cold drafts you feel close to the exterior walls, around electrical outlets and window trim or cold drafts in the basement are symptoms of the stack effect. You may notice that the surface of the floor right above the basement or crawl space is very cold in the winter months. In the attic, air leakage due to the stack effect will happen in the insulation. You will notice discoloration from the dust deposited on the fine fibers by the rising air.

Fixing the Stack Effect in Homes & Tall, High Rise Buildings

The stack effect has three factors that will determine how strong it is.
1. The height of your living space. Taller buildings will have stronger convection.
2. The interior-exterior temperature difference. The bigger the difference, the bigger the effect will be.
3. The amount of leakage in the home.
You obviously can’t do anything about the first two, so it’s important to do something about the third, which is air leaks. Air leaks in the attic need to be sealed as these are areas where most of the warm air will escape. Your home will need to be professionally sealed to short-circuit the stack effect. The solution is to seal the openings and make sure the insulation is doing it’s job.

HVAC Services in Springfield, Granby, Holyoke, South Hadley, Monson, Chicopee City & Agawam Massachusetts

The stack effect causes energy problems. Your heating system has to work harder and longer to keep things comfortable in the home when heated air is leaving and cold air is entering. This cycle will continue 24/7 so you will be spending a lot of money to keep your home comfortable. Contact Ambient Heating & Air Conditioning to help you get the stack effect under control.