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That's comparing single pane windows without storms (rare in my experience these days) to double pane windows. This gives the comparison between the single pane with storms to double panes:
The "wasteful new windows" I was referring to me is the fact that a lot of windows these days are designed to block the sun's infrared (transporting heat) rays as a way to lower cooling costs, called low solar gain windows. But this will increase your heating costs if your windows gain sun exposure, potentially raising your energy use. I leave my windows open most of the summer so the low solar gain windows have no effect on my summer energy use but raise my winter energy use.
After I posted last night I got to thinking about my parents' old house in suburban Pittsburgh. The downstairs windows, with the exception of the one over the kitchen sink (not the only window in that kitchen) are all large, single pane windows that do not open and did not have storm windows. Only the kitchen window and the upstairs windows opened and had the storm/screen combination. I remember at one time some salesman tried to talk my dad into getting a new, double pane living room window. He told my dad it would save on his heating bill, to which my dad replied that he would be dead before that happened. Dad didn't replace the window and died a few years later. I don't know how many houses there are in similar situations.
When we first moved to Denver in 1980, most houses more than 5 years old were built w/o double panes, storms, etc. We knew lots of people who were slowly replacing their windows w/double pane, usually one side of the house at a time. We rented a duplex that had such windows, built 1960. The first house we bought was built in 1978 and had the double panes with the built-in screens, as did our present house, built 1980. Most of the houses in our neighborhood are similar vinatge, and most of our neighbors have never replaced their windows, thus debunking the idea that these windows only last 10 years. We replaced our windows a few years ago, mostly b/c the bedroom windows didn't close properly due to warping of the wood frames.
I've never heard of the type of window you describe in the bold; I'd guess they're not sold here where keeping one's house warm in winter is more of a concern than reducing heat gain in the summer.
Dual-pane windows have an air gap a fraction of an inch thick; storm windows provide an air gap of several inches. It's primarily the air mass in between the window glass that provides the insulation in a storm window or dual-pane; the advantage of a dual-pane over a single pane is like wearing two T-shirts instead of one T-shirt in winter, instead of a winter coat. Windows represent about 3% of a house's surface area, and insulating the walls and roof give a lot more cost/benefit return than dual-pane windows. But keeping single-pane windows in good repair (sealing cracks, caulking, etc.) and using low-tech solutions like insulating curtains can bring them up to par with dual-panes for a fraction of the cost.
Dual-pane windows have an air gap a fraction of an inch thick; storm windows provide an air gap of several inches. It's primarily the air mass in between the window glass that provides the insulation in a storm window or dual-pane; the advantage of a dual-pane over a single pane is like wearing two T-shirts instead of one T-shirt in winter, instead of a winter coat. Windows represent about 3% of a house's surface area, and insulating the walls and roof give a lot more cost/benefit return than dual-pane windows. But keeping single-pane windows in good repair (sealing cracks, caulking, etc.) and using low-tech solutions like insulating curtains can bring them up to par with dual-panes for a fraction of the cost.
I. . . . don't. . . . think. . . . so! Also, keep in mind that people with double pane windows do the same, and usually have curtains as well.
Also, I don't think you "get it" about layering. It's not two T-shirts instead of a coat. In fact, that's a pretty bad analogy and I'm not going to go further with it. Come out here to CO and we'll teach you about layering!
Last edited by Katarina Witt; 11-22-2011 at 03:10 PM..
Reason: fix it
I. . . . don't. . . . think. . . . so! Also, keep in mind that people with double pane windows do the same, and usually have curtains as well.
Also, I don't think you "get it" about layering. It's not two T-shirts instead of a coat. In fact, that's a pretty bad analogy and I'm not going to go further with it. Come out here to CO and we'll teach you about layering!
Single-pane windows have an R-value of a bit less than 1. Dual-pane windows of various thicknesses have an R-value between 1.6 and 3. A relatively thin layer of fiberglass insulation has an R-value of 11. As I said, if a single-pane window is one T-shirt, a dual-pane window is two T-shirts: marginally better than one, but still pretty feeble compared to actual insulation. The same chart lists drapes or blinds as being worth only .29, but insulated curtains are easy to find with an R-value of 4-6. Storm windows on the outside are given an R-value of 1, but one can also use inside window covers (an acrylic sheet that snaps inside an existing wood window frame, behind the window) have a combined R-value of 4.8.
Single-pane windows have an R-value of a bit less than 1. Dual-pane windows of various thicknesses have an R-value between 1.6 and 3. A relatively thin layer of fiberglass insulation has an R-value of 11. As I said, if a single-pane window is one T-shirt, a dual-pane window is two T-shirts: marginally better than one, but still pretty feeble compared to actual insulation. The same chart lists drapes or blinds as being worth only .29, but insulated curtains are easy to find with an R-value of 4-6. Storm windows on the outside are given an R-value of 1, but one can also use inside window covers (an acrylic sheet that snaps inside an existing wood window frame, behind the window) have a combined R-value of 4.8.
What am I wrong about? You obviously don't know how to do math, if you think that 1.6 is not almost twice .85 (the R-value of single pane glass).
All of the above can be added to a double-paned window as well.
You're comparing single-pane without storms to double paned. I think wburg was comparing single pane with storms to double paned. I would do the same myself as I never encountered single paned without storms in old houses. Though, my parents' house (late 50s) might have a single paned without storms that can't open like your parent's house did. I'm not sure if it is single paned, but always seems especially drafty in the winter, with water condensing on the inside.
From, the r-value of single pane glass + storm is 2.0 not 0.85. I've never seen double pane windows + storm before, but there are triple paned ones.
Most of the houses in our neighborhood are similar vinatge, and most of our neighbors have never replaced their windows, thus debunking the idea that these windows only last 10 years. We replaced our windows a few years ago, mostly b/c the bedroom windows didn't close properly due to warping of the wood frames.
My parents replaced most of the windows in their house when they moved in. It's been over 15 years and no sign of them getting old. They just replaced a few of the original ones that they didn't get around to replacing when they moved in.
Quote:
I've never heard of the type of window you describe in the bold; I'd guess they're not sold here where keeping one's house warm in winter is more of a concern than reducing heat gain in the summer.
They are here; a landlord added them to an apartment I used to live in. Unless you pay attention to the window's label you won't know what you're getting. They're described here (under the Solar Gain Coefficient):
Long Island, Massachusetts and almost all of Colorado fall under the "cold climate" zone where heating is the biggest concern. But a lot of windows are sold nationally without regard to the climate. For a couple of years, you could only get an energy tax credit if you bought the low solar gain windows, regardless of your climate. (Can't find the source on that at the moment).
What am I wrong about? You obviously don't know how to do math, if you think that 1.6 is not almost twice .85 (the R-value of single pane glass).
All of the above can be added to a double-paned window as well.
And two T-shirts are twice as thick as one T-shirt...but only a tenth as thick as a coat (as in, a double-paned window is only a tenth as much R-value as fiberglass insulation, suggesting that insulation in the walls and ceiling matter a lot more than whether your windows are single or dual pane.)
And while all of the above can be added to a dual-pane window, once you add it all together, there is very little difference between all that stuff with a single pane vs. all that stuff with a dual pane...except with the original single pane you get much greater durability (lifespan 100+ years vs. 10-15 years) and cheaper (a few bucks to weatherstrip an old window vs. hundreds per dual-pane) and greener (old-growth redwood that stays in place vs. a growing stack of vinyl frames in the landfill.) And assuming you get some magical dual-pane that never breaks seal for the same price as the cheap ones, it still takes 400 years of utility bills before you get your investment price back.
And two T-shirts are twice as thick as one T-shirt...but only a tenth as thick as a coat (as in, a double-paned window is only a tenth as much R-value as fiberglass insulation, suggesting that insulation in the walls and ceiling matter a lot more than whether your windows are single or dual pane.)
And while all of the above can be added to a dual-pane window, once you add it all together, there is very little difference between all that stuff with a single pane vs. all that stuff with a dual pane...except with the original single pane you get much greater durability (lifespan 100+ years vs. 10-15 years) and cheaper (a few bucks to weatherstrip an old window vs. hundreds per dual-pane) and greener (old-growth redwood that stays in place vs. a growing stack of vinyl frames in the landfill.) And assuming you get some magical dual-pane that never breaks seal for the same price as the cheap ones, it still takes 400 years of utility bills before you get your investment price back.
I keep telling you it is hyperbole that double pane windows only last 10-15 years, no matter how many times you say it it's not true. And since when do single pane windows never break? Why do you never post any links to this stuff? If it's true, it shouldn't be hard to find. I also keep saying redwood is not used much outside of California. Why would it cost more to weatherstrip a double pane window.
I keep telling you it is hyperbole that double pane windows only last 10-15 years, no matter how many times you say it it's not true. And since when do single pane windows never break? Why do you never post any links to this stuff? If it's true, it shouldn't be hard to find. I also keep saying redwood is not used much outside of California. Why would it cost more to weatherstrip a double pane window.
Because other sorts of old-growth wood are used outside of California, and the same principle applies.
Unlike dual-pane windows, single-pane windows aren't filled with argon and.or krypton gas, and it is the leaking out of the gas that causes dual-pane windows to fail in a decade or so. Argon is denser than air, and that is what makes a dual-pane window have a higher R-value than a single-pane window. It's invisible, so you can't tell until you see condensation forming inside the pane. Weatherstripping doesn't fix the problem, since the gas is already gone.
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