Many of us nowadays are taught that we ought to have vents to remove smelly air (e.g. cooking odours), air laden with moisture (e.g. Bathroom air) and air that might be contaminated with our day-to-day living or infiltrated from below the home (e.g. Radon).
Blindly we are led down the path of installing the best, most powerful, quietest vents we can in a fit to make our homes more livable.
How many of us think, when installing these vents, that the vents we are installing could be doing more harm than good? Really??
Didn’t think so!
As homes are being built more and more energy efficient, they are becoming what is known as “tight”. While I suppose that could be a term the defines their frugality in terms of energy costs, it also means that they are becoming less impervious to air penetration.
Think what happens if you put your mouth around the open neck of a bottle and you suck in as hard as possible. Most times you won’t get very far, as the vacuum inside the bottle you are trying to create will be too powerful for your little puckering lips, and the worst that will happen is your tongue might get sucked into the bottle as air tries to re-enter it.
Now a bottle is pretty “tight”, but modern homes are going in that direction.
So what do you think happens if you have a 450CFM (Cubic feet per minute) cooker hood, and a 150CFM Bathroom vent, a 160CFM Clothes dryer and possibly a 450CFM whole house fan all running at the same time venting air from inside the house to the outside?
Well if you have an old rickety house, that’s not too tight, you’ll get around 1,050 Cubic feet of air squeezing in through gaps in the doors and windows or through the roof or sill plates.
But if you have a snazzy new, energy efficient, air tight home, you are essentially living inside a vacuum cleaner. The 1050 Cubic Feet per Minute amount of vented air has to come from somewhere.
Either, as the air is evacuated from the home, it will be drawn out of the inhabitants with vulgar noises and squeals as the ears pop, or more likely it will be drawn in from areas it’s not supposed to be drawn in from, such as gas flues, or cracks in the basement or basement drains.
What you will be doing by turning on all the vents to remove the cooking smells, bathroom steam and household humidity, is drawing in carbon monoxide, unburned fuels, sub soil gases (including radon) and sewer gases.
It is important that you ensure that when you think about venting that nasty horrible air, you think equally hard about the make-up air you need to support the fact that, yes indeed, your house sucks!
Now you’ve turned your house from a smelly moist concern, into a possibly lethal concoction of noxious, explosive and radioactive gases.