The Prairie Spy

Alan “Lindy” Linda

This is about windows. Some folks will read this because, well, they don’t have anything better to do. Some will read it because they either are now or are in the future building or remodeling a home. Or know someone who is.

When I was teaching HVAC students, I spent a lot of time and effort drilling them on the calculations for heat loss and gain. Windows, as compared to walls, are not good at keeping your heat in, in the winter, and the heat out, in the summer. Plus new ones, or quote “replacement windows” are expensive. So here’s what I’ve learned about windows.

First, about older windows: It is often not the window itself, specifically the glass, that is causing heat loss in older homes. More often than not, it is the framework around that window, which is hidden by sheetrock and trim, that is responsible. When old windows are replaced by new windows, often,  it is the framework that isn’t  changed. Replacement windows are often merely carved into the old windows. Hmmm. Not good. You have to get into that old wall construction to do this right. Point one.

Low E windows. I didn’t grasp the bad points of Low E windows until I replaced a bunch of windows in this old house. Yes, I got clear back to the framework, used expanding caulk to seal stuff up, did everything I knew right.

There is a good thing about Low E glass, but first a quick lesson on summer heat gain. In the summer, when the sun is directly above you at midday, there is no window heat gain to trigger your air conditioning unit. But. In the morning and afternoon, when that sun beats itself in through the east and west windows–Hey! Now’s when Low E pays for itself. South windows? Who cares. No sun in those, for the most part.

But in the winter? Those new windows that I expected warm sunshine to come through at midday in the winter, when the old windows–non Low E–let that sun’s heat in? Uh, uh. No warm sunshine then. The Low E kept it out. I hate that. I should have known that. Been kicking myself ever since.

Yes, sure, Low E does help keep heat in your house in the winter, that’s a fact. (Hmmm. Doesn’t that mean it keeps heat in your house in the summer too? Hmmmm.) But I really missed the warmth of those south windows in the winter, sun beating in, sun reflecting off white snow beating in. The reason I learned this is that I kept a couple of older south-facing windows, and in the winter, the heat from the sun through those is wonderful. But not in the rooms that I spent a lot of money on Low E. Nope.

So. There is no way that I would put Low E windows in the south-facing walls of my house again. I have a lot that are. I have a few that are not. I have a good comparison against which to make this decision.

If you’re thinking windows. Think about all this.