windows – casement /dbl hung and low-E
Hi folks,
I need to replace windows in a Colorado home built in 1983. Current windows are wood casement, and a few of them are difficult to close. I’m thinking of replacing with double hung.
To be honest, I’m getting a bit confused. I’d like some input on the pros/cons of casement vs double hung.
Also aluminum vs vinyl vs wood. Some of these windows take a beating from sun, so what’s more durable in that scenario?
And one last thing, any opinions on Low-E? The house is passive solar and depends to a large degree on solar gain. Does low-E reduce solar gain in winter?
Thanks,
Mike
Replies
I would vote wood clad casements, but I don't have that much experience with different types.
I have no idea about the low e
I do think that it is difficult to get cheap windows that are any good. There may be expensive windows that are not worth the money, but I am not aware of any cheap windows that are as good as, say, Andersen.
Mostly I'm posting to draw attention to your question.
Rich Beckman
Coming to the Fest? Don't forget pencils!!!!!!!!!!!!!
Yes low-e will reduce the solar gain, that is the purpose of it. That said, in your situation IMO get Argon filled insulated units and have them leave off the Low-e. Yes, they will scratch their head and won't understand. You want the solor gain of the glass area, how Argon gas works is that it is inert at all household tempetures. In a normal sealed unit as the sun strikes the lower portion of the glass the air inside heats up and rises, as the air rises and get out of the sunlight it cools and falls. In effect what you end up with is a cycling of the air in the sealed unit and as it moves across the glass surface it transfers the heat/cold to the glass. With Argon the gas inside the sealed unit does not move and therfore reduces the transfer of heat/cold.
Casements vs DH is a major design issue, however, I would just say that in general, casements are mechanically superior to DH, in terms of air infiltration around the sashes. Difficulty closing any window maybe a sign of inferior windows but more likely is due to inferior installation, poor maintenance, and/or other building issues (like settling). If the home was a tract house of any sort, you can count on it having relatively cheap windows, and "production-minded" installers.
Of course, a cheap casement unit is not likely to be superior to a quality DH. I believe that alum. clad or vinyl clad exteriors are superior in just about all exposure situations. Most solid vinyl windows are for the budget minded, although there a few good ones out there.
Above all else, installation details are hugely critical. You will spend a bucket of money on good windows so you want an installer who knows how to do it correctly.
...aluminum vs vinyl vs wood. Some of these windows take a beating from sun, so what's more durable in that scenario?
I think aluminum is a poor choice for windows. Why? It's a great conductor of heat, which is typically something you're trying to avoid with windows.
Somebody mentioned clad windows. Although it may vary with the climate of the region, I've seen bad things happen to clad windows where I live in the NW. What seems to happen is that the cladding expands and contracts at a different rate than the wood core. Then, the adhesive bond fails, and moisture starts to get behind the cladding, and rot starts from the inside out. I've got a client with some very expensive clad doors; all four have completely failed at the bottom rail.
I typically steer my clients towards either wood or vinyl (there are other materials, too, but I just don't have any experience with them yet). If they want a traditional look -- and especially if they have stained trim -- I'll recommend wood. If they are fine with white windows, then vinyl will fit in to that scheme just fine.
In terms of mechanical operation and thermal performance, vinyl windows can be great. I've used the higher-end Certainteed product on numerous occasions and have been happy with them every time.
As far as the high sun exposure you mentioned, I can only point out that the sun will destroy everything it encounters eventually. The only thing you can do to help out here is to choose a lighter color that will reflect more radiation than a darker color would.
I'd like some input on the pros/cons of casement vs double hung.
A lot of it just has to do with what style you prefer to look at.
As far as air infiltration, I'd agree with others here in saying that modern casements are generally more airtight than double-hungs. So if airtight is important to you, that may be a major consideration.
Ease of operation is another consideration. The copious amount of compression weatherstripping that is used on double-hung units these days makes operation nearly impossible; the mechanical advantage offered by a crank-operated casement comes in handy here. For reasons that elude me, vinyl double-hung units seem to operate much more smoothly and efficiently than wood double-hungs.
If opting for casements, I would personally stick with fairly modest sizes. Double-insulated sash weighs so much that it really takes a toll on the hinges -- as well as the joinery if wood -- and I'm not aware of a single major manufacturer that uses quality wood joinery these days. Sag (due to hinge wear and joinery failure) is probably the reason you're experiencing problems with the casements you have right now.
low-E coatinWhen window-shopping, keep in mind that low-E coatings are not one-size-fits-all. They can be engineered for different functions: Coatings with high solar heat gain reduce heat loss from the inside and maximize the amount of heat transferred from the outside, a desirable quality in cold climates. Those with low solar heat gain reduce heat loss in winter, but also reduce heat gain in summer. So if you live in a warm climate your, a/c does not have to work as hard. And then there are spectrally selective gs, which are designed to admit a higher portion of visible light.
Do a google for low E coatings and find what suits your climate. Without knowing your specific location (lat.& long.) as well as site oreintation, roof over hang, and exterior finishes it would be a stretch for anyone to say low e windows are correct or incorrect for you. As important as windows are in a passive solar home, managing them is almost equaly important.
Our home design is also passive solar. As part of the design process our engineer included a management recommendations for window treatment. With a 85' south facing walland lots of glazing it became very important to close drapes, shdes, etc. durring summer months to reduce solar gain. The reverse happens in the winter months when we want the solar gain. Of course we are likely further south than you, so our windows on that side of the house are low-e.
Point is, one size does not fit all when talking passive solar and window type and design features.
Dave
Thanks to all for your input.
Regarding low-e.....
I'm in the Rockies at 8500 ft. Latitude 38.993N longitude 105.056W. Wall orientation is due magnetic south. It's 2 stories high, and the overhang is about 3 feet. The house really doesn't ever get too hot. Max temps here in the summer rarely hit 90F.
There's a temperature controlled, interior insulated curtain that covers almost all of the windows in the south wall when activated. That's a critical piece of the puzzle.
So, I guess I should concentrate on windows that maximize gain in the winter. But I'm beginning to think low-e is not necessary.
Thanks again!
Mike
As mentioned previously, there are different types of LowE coatings available.
Some LowE coatings allow direct solar gain while blocking "indirect" heat from going thru the window. These types of coating are highly recommended for solar applications because in the winter they allow heat to enter and then keep it inside the home when the sun is no longer shining on the glass.
telemarker,
The real benefit with regard to thermal protection of Low E windows is that most are argon filled.. the inert gas Argon provides better heat retention than simple air..
However don't assume that it's as simple as getting argon filled low E windows..(which most low E windows are)
Frankly I don't like any of the ways they contain argon. At the absolute best you might still have some measure of argon a decade after the window is installed.. Worst case, it will leak out either before or during installation.. You won't have any indication that the Argon is doing it's job unless you have access to labratory grade equipment.
Your altitude will be in conflict with the pressurized argon.. increasing it's tendency to leak out..
Having said that let's discuss double hung versis casement windows. The location on the building will determine which is superior in what location from a functional stand point. Your house may look goofy with either double hung or casement windows depending on the style of your house..
Double hung windows perform best when placed on a wall with normal wind flow coming directly at the wall. Casement windows can perform better on walls where the dominate wind pattern is along side the building.. (orientation will determine which is better)
One poorly understood part of a double hung window is why the top comes down.. Why not have the top fixed and just the bottom go up? Well, the reason is that by opening the window a crack at the top, warm air rising will have a place to escape while cooler heavier air can come in to replace it.. In my house the differance can be over 10 degrees cooler! I open the top about 4 inches and raise the bottom untill it meets the top. Maxium airflow!
Edited 7/19/2007 8:28 am ET by frenchy
The frame is so important. Why not go for the highest-rated frames in terms of energy efficiency? That would be fiberglass.
As someone else mentioned, the choice between DH and casement windows is a design one first. Second, I'd say right away that casements are easier to handle when opening, double hungs can get pretty heavy, especially over time.
In windy areas, double hung windows can be better as casement hardware/window arms can get battered by the winds. Double hungs are also good in tight places, because they don't take up much space.
As for wind/water infiltration, I thought DH windows were much better than casements, but I may be wrong, its definitely something to check out though.
When deciding on wood, clad-wood, or PVC, I'd recommend clad-wood all the way, because they are easier to maintain, and you can keep the all-wood interior. All-wood windows are hard to maintain and keep working smoothly over a long period of time.
I used to work for Loewen Windows, and firmly believe them to be the best wood windows around.... none of the other big manufacturers use Douglas Fir in their windows plus extruded aluminium for their clad. They are far superior to others. A few years ago I did installs for Pella for a summer, and was impressed with a lot of their features and options, but I'd still pick Loewen in the end.
SS
You may have a hard time finding a manufacturer who will ship argon-filled windows to 8,500'. They generally have to be vented for shipping with a capillary tube that's pinched-off during installation. I believe that there's now a glazier in Colorado Springs that is doing some custom fitments for window manufacturers, and one of the major manufacturers (forget which) that has a top-secret way that they claim works. I'd definately go with low-E, specified by application as mentioned above. I like fiberglass frame windows under the Colorado sun because the rates of thermal expansion/contraction for the frames & glass is more similar than with other materials. This relieves the seals of the main cause of strain failure.
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