|What is Stack Effect?|
STACK EFFECT what is it, effects and cure.
Stack effect is comparison to how a chimney functions. Warm air enters the bottom, rises and heats the chimney flu creating more air flow as temperature of chimney rises.
Same with a house, as the house will act as giant sized chimney (for those with a wood stove, open and close air damper, open damper increases stack effect, close damper lessens stack effect).
Let's use a three storey home, 2 floors plus a basement.
The basement allows cool air to enter into the home through clothes dryer vent, poorly sealed windows and doors, poorly sealed or no vapor barrier, plus anyplace that allows outside air to enter the home.
This air will rise due to the upper floor areas being warmed and that air escaping to exterior atmosphere through any unsealed area.. The warmer the air the more the air rises and the more pressure the warmed air creates on upper envelope of house. It not only creates pressure on upper level to escape, it creates a vacuum on lower areas of home due to escaping therefore air is being sucked into the house in lower level.
Think of a large soda bottle, hold with spout up and try and blow air into the bottle. Hmm! No air movement. . This is exactly the same as your home should be, sealed tight. place a straw sized hole in bottom and blow again. WOW! easy to blow through the air. That is your home when not sealed tight.
Just something to think about on a huge scale, imagine the stack effect of a 35 storey building and the precautions that must be designed to prevent such movement of air.
Now! If your home is sealed tight, your homes air will become stagnant and unhealthy and this where an HRV (Heat Recovery Ventilator) comes into play. You totally sealed your home and the HRV brings in fresh air and exhausts stale air.
The HRV in winter will prewarm the entering air with exhausting warm air and in summer cool the incoming warm air with exhausting cool air.
Ah you say! Why seal the house in the first place, how stupid! Reason, house is sealed properly, no drafts, no build up of moisture in air leakage areas, control of proper amount of fresh air exchanged. Ahhh! Fresh clean air in house, hmmm! What do you have in your home that creates odors.
When I am building my homes I think of them as a huge beer coolers, totally sealed and then ventilated properly for fresh air.
Learned this on the hot beaches of the Okanagan Valley. Built my own coolers out of styrofoam, c/w a reflective aluminum cover. MY Beer was always coolest and the sandwiches were always fresh longer than anyone elses.
Gotya you say! You seal your beer cooler although no fresh air. Oh yes that is true, although at end of day I, (opps) wife opens cooler and washes, plus leaves lid open.
Oh how one gathers the basics, then begins to research!
Once again, one must understand the effects of planning for proper insulation, vapor retarders, air barriers and ventilation when constructing or renovating.
David Palmer is the owner of Big Block Home Inspections and is an expert in home inspections in the Barrie Area. He has built, renovated and inspected structures for the last 45 years.