Having a home where the stack effect, also knows as stack ventilation or the chimney effect, is taking place has two major consequences, unnecessarily high energy bills and diminished levels of comfort. Winter is the season where the stacking effect is the most noticeable. This is due to the fact that there’s a serious discrepancy between indoor and outdoor temperatures. Here’s what you need to know about the stack effect and how to stop its consequences on your home.
What Is Stack Effect Ventilation?
The stacking effect causes your home to draw air from your basement up to your attic through your walls during the winter months. This is because the colder exterior air is denser and enters your home through gaps in the lowest level of your home. Upon entry, it creates an upward circulation of warm air from your furnace through your floors and ceilings until it reaches your attic where it exits the home via areas that have not been fully sealed off. If moisture condenses on the underside of roof sheathing, it can easily cause frost in attics to form.
In the summer months, the opposite is true and outside air enters through your crevices. The warm air is pulled down your walls to your home’s lowest level where the air escapes through exterior gaps in your home.
The reverse stack effect causes your home’s HVAC system to work harder than it should have to, increasing your utility bills. It can also lead to the premature failure of your furnace and air conditioner because they are running more frequently than they should have to. The reverse stack effect can also compromise your home’s indoor air quality. In some homes, attics become home to pests such as squirrels, mice, and bats. In the summer months, when attic air is being forced downward, it can come in contact with fecal matter these pests have left, causing a decline in the quality of your home’s air.
Preventing The Stack Effect With Home Insulation & Ventilation
Critical steps towards preventing the stack effect are caulking, weather-stripping, and attic air sealing. Areas of the attic that often require the installation of spray foam insulation to prevent leaking include can lights, plumbing vents, exhaust fans, and stove vents. In the basement, areas that need sealing include the rim joists, plumbing penetrations, and the sill plate.
Fast Facts About Blower Door Testing
A reputable insulation contractor using diagnostic testing such as infrared imaging and blower door testing can help you pinpoint areas where your home is leaking air. Winter provides the best opportunity for these types of diagnostic testing because of the significant variance between indoor and outdoor temperatures. Energy audits and performance testing allow our installers to understand what needs to be addressed to combat the chimney effect, whether that’s home ventilation, insulation, air leaks, or a combination of them.