What is Stack effect?

Teddy Bear, Can you provide a brief explanation of stack effect? Thanks – Mike

Mike,

The stack effect is a winter or cold weather effect on the home. This occurs when the heated air inside the home is lighter than the outside cold air. Because it’s lighter than outside air, the heated air puts pressure on the top of the home. The lighter air escapes out of imperfections in the top of the home. The escaping air causes a negative pressure on the lower part of the home. An equal amount of fresh air is sucked in through the lower imperfections of the home. The colder the outdoor temperatures, the greater the pressures outward/inward on the home. The wind is the other pressure on the home.

Depending on how tight your home is, during cold winter weather usually enough fresh air exfiltrates/infiltrates the home that fresh air ventilation is not necessary.  But during the summer, the wind is the only natural pressure on the home.  Therefore, homes require more mechanical fresh air ventilation during the summer when the windows are closed.  Of course, if you have a fairly tightly constructed home you may need mechanical fresh air year-round.

Hope this helps you.

Regards,

Teddy Bear