By Patrick O’Donnell
Special to East Penn Energy Solutions
Did you know that your house needs to breathe?
That’s right: Proper airflow is essential to a healthy, energy-efficient house. It’s a fact that sometimes gets lost in all the talk of replacing windows, sealing up air leaks and ensuring that a home’s inside space is well-insulated.
Without proper airflow, a home will not function properly. Too much airflow will lead to the loss of your conditioned air — hot or cold — and drastically increase energy costs. Too little will not vent heat properly in the summer, will trap moisture inside the home (leading to problems with mold and mildew), and will not bring in enough clean, fresh air for healthful living.
The idea of proper airflow is one that most people have wrong, says East Penn Energy’s David Wallace.
“The thing that keeps coming back is that there are serious misconceptions about air flow,” David says. “People often complain about drafts in their home, and they always point to windows. Windows are always the villain in their minds,” he says. “However, knowing what I know about building science, I know that windows are a symptom. They’re not the cause. And almost like our medicine, people want to treat the symptoms but not the root cause.”
The cause, David says, is a very simple principle that’s known in the building trade as the “stack effect.” Simply put, any time there’s a difference in temperature — even if it’s just a couple of degrees — you’re going to have air movement and a resulting change in air pressure. That change in air pressure can either pull in or push out air through those windows.
“Typically, what we get real concerned about is in the winter seasons, because we spend so much of our time heating rather than cooling, your house will be warmer than it is outside,” David says. “The hot air rises up through your house, heats up the second floor of your house, and finds its way out through the attic. Well, that air’s got to be replaced. So where does it come in? It comes in through the windows, yes, but it also comes in at the lowest possible point of the house.”
The idea, he says, is to control this air exchange. Too much control leads to living in a “plastic bag,” he says, which can be toxic. Too little and it’s like living in a barn.
So where’s the middle ground? That’s where an auditor — someone well versed in building science (like East Penn Energy Solutions) — comes in. “There are ways of finding out if a building is too ‘tight,’ and there are ways of dealing with that,” David says. He also points out that the reverse is true: there are fairly simple remedies available to seal up a building that has too much airflow. “That’s really the reason behind the audit – to find out how to control the airflow.”
Which brings us back to David’s earlier statement about windows. “If you control the airflow, usually in the higher and lower levels of the house, that pressure differential tends to go away. So whatever happens in the middle zones— the first and second floors; i.e., the windows — the cause for that draft through the windows largely goes away, because there’s not that intense draw.”
What that means for the homeowner, David says, is that there’s often a much more cost-effective way to deal with a drafty home. “When you spend $500 a window — which is cheap — and you calculate that improvement over the square footage of the house, then look at the cost of that project and what your net gain is, and you compare those numbers to the amount of air sealing and insulation you can get done and the dollar amount and net gain of those improvements, it by far outweighs the benefit of getting new windows,” he says.
“Now, that does not mean windows are a bad investment. But I don’t normally recommend them as a first line of defense, because usually leaky windows are a symptom of something else,” David says. “Definitely replace windows if they’re second, third or fourth on the priority list and you have the funds available, but it’s not the place to start.”
“It’s basic building science,” David says. “Nine times out of ten, I go into a home’s basement and it’s practically wide open. You know the air is coming in there, and it’s got to go out somewhere.” That somewhere, he says, is often the windows. Limiting the air flow — and the resulting stack effect — will usually solve the problem.
So instead of breaking the bank and spending a fortune on new windows, contact East Penn Energy Solutions today to see if there are better options available to you. A simple home energy audit could save you a small fortune in energy costs and unneeded upgrades.