I’m choosing windows. I know there are lots of opinions here about what’s best, but I’m using vinyl. Probably going to use Milgard. In choosing between the less expensive windows (in my case Milgard Style Line) or more expensive windows (Milgard Classic series) how much difference does it make in the heating of the home? (Or going to a different brand of vinyl window?)
I know that some of you are going to start thinking U value, etc. Both of the windows I’m looking at are double pane, sc low-e. It’s easy to check the fenestration association website and get U value info.
What I want to know is: What percentage of the total heat loss of a typical new home are we talking about between a little better U value or a little worse?
I know I’m being vague with all the details, but none-the-less: You or I may think that a Lincoln or a Mercedes or a Lexus is the finest car made, but do we all drive them? No. Why? They may be fine, but in the context of each of our personal budgets, that fine quality may not be worth it to us. So, how much actual difference is there?
Or is the price/frame size mostly a durability issue and not a energy issue?
Thanks for opinions offered!
Any jackass can kick down a barn, but it takes a carpenter to build one.
Edited 8/4/2003 4:49:52 PM ET by Hasbeen
Replies
Usually, the difference in price in a mnufacturer's line of windows has to do with the construction of the window and how much visible glass there is.
You can get a screwed sash window and frame (the cheapest), or a welded sash and frame. You can also get a thinner vinyl extrusion that is steel reinforced that allows you to have more glass for the same window size.
I like the Simonton windows myself.
So do you mean that more visible glass costs more or less (usually)?
Milgard's are less expensive with more glass showing...Any jackass can kick down a barn, but it takes a carpenter to build one.
Usually, more glass, more money.
As far as R values,
It matters some, but the installation and the draft surrounding the old frame matters more.
has... it depends ( hah )..
if your climate is mild... if your walls are leakers.. if you don't have much insul in your attic.. then the windows don't mean sh*t..
we live in a 6000 Degree Day climate.. so it all means a lot..
the basic formula is (U x A x deltaT = btuH), U is the reciprocal of R..so
1/R x A x deltaT = btuH..
if you have a ranch say 24 x 40 with 12 windows of 3x5 and 2 doors of 3 x 7, and your interior design temp is 70 and theoutside temp in jan is 10..
delta T is 60
gross wall area is 128 x 9 = 1152
attic area is 960
1st floor area is 960
windows total area is 180, doors area is 40
net wall is ( 1152-180-40 = 932)..
disregarding windloss and edge leak, and just for comparison..run the numbers
attic r = 40
wall r = 20
1st floor over crawl is r20
windows are r2, doors are r10
attic loss = (1/40x960x60) (1/R x Area x deltaT) = 1440 btuH
net wall loss = (1/20x932x60)= 2796
first floor loss to crawl = (1/20x960x40) = 1920 ( assumes crawl is 30 deg )
window loss = (1/2 x 180 x 60 ) = 5400
door loss = ( 1/10 x 40 x 60 ) = 240
total static loss = (1440+2796+1920+5400+240 ) = 11796 btuH.. so teh windows are almost HALF of the total static loss..
now change the window to R3..
(1/3 x 180 x 60 )= 3600 btuH...... big difference , eh?
bottom line... after you've taken care of the attic and walls... you've still got all these giant holes in your house called WINDOWS....
hey.. the numbers above are real numbers.. but they do NOT represent a sophisticated heat loss calc.. so ..
they do truly represent the relationship of windows to the rest of your comfort envelope
Mike Smith Rhode Island : Design / Build / Repair / Restore
Thanks, Mike! That was very helpful. I won't pretend to understand all of it, but I get the drift... :)
Spurred on by your post, I found a university website that indicates that my town has an average of 5,400 degree days, although it has been as much as 15% lower in recent years. It is one the mildest places in Colorado, according to the CSU info. Sounds good to me!
Thanks again.Any jackass can kick down a barn, but it takes a carpenter to build one.
Mike's looking at it right side up.
ASHRAE lists you at 5462 with light wind velocity, <7mph during cold extreme hours. We have 4150 degree-days. My calculations, that I'll spare you, show that with low e fixed (no leaking) windows on our next place I still get almost 3/4 of my heat loss through the windows. But that doesn't necessarily mean I want to pay for a third pane or exotic gasses.
When you know how much heat you'll lose, you can make an intelligent decision as to how much to spend on the windows. In our case 3/4 still isn't much and shows that my proposed wall insulation is probably excessive. PAHS Designer/Builder- Bury it!
vatom.. right on... i can make my windows account for 90% of the total loss .. if i beef up the other areas..
my own inclination if to try to remember that most of us with winter only have our heat on for about 5 months.. so put the windows in so you can enjoy the other 7, but beef up the attic, wall , and floor inulation so you can be economically comfortable when the wind blows out of canada...
our minimum window spec is low-e....Mike Smith Rhode Island : Design / Build / Repair / Restore
I expect to get about 20% of my heat from the sun and I plan to burn wood (which I enjoy doing). Part of the windows will be fixed.
If I remember correctly, the windows I looked at were quoted as R 3.5 or close. I think it'll be fine and the thicker frames are only very slightly better.
What type of wall / insulation are you going with?Any jackass can kick down a barn, but it takes a carpenter to build one.
ya like mike said put the windows in so you can enjoy the other 7, and for the weeks that are really cold in the 5 put something in the window to insulate it. i asked my wife to make curtains from old army blankets, all wool, that hang inside of mini blinds and are easily removed. they can be died any color, and are mostly hidden by blinds anyway. there must be other ways to make "storm curtains", custom cut foam core futons? also with the vinyl windows i just discovered that my old method of installing aluminum frame windows doesn't work. the old way is to center window in R.O. then fasten, but with vinyl they sag and then don't close so well. fir the R.O. at the bottom to desired height with a dead nuts level strip of ply and set window on ply strip and fasten. more better! p.s. don't forget to flash with bituthane.
What type of wall / insulation are you going with?
Apples and oranges I'm afraid. I only consider underground (PAHS) for any heated building. I have cast-in-place concrete covered with 2 1/2" of xps for the exposed walls. Next one will get only 2", like the client house.
We ventilate with a small air system that does a 2 hr total airchange. Immensely cheaper than buying opening windows, which generally aren't opened much anyway when it's cold out. This also gives the opportunity to filter pollens and pollutants as well as dehumidify. As we're constructing the windows, copper cladding to match the sheathing worked very well. Anybody can make a good fixed window with some good weatherstripping. Client house had 3' x 10'ers, lots of them. Window budget was $5k. Egress, of course, has to be dealt with.
Building dept. has by now been so confused by my approach that they figure it'll work and ignore the details. They don't want to know. LOL
Far as I can tell, everybody loves to get close to a wood stove on a cold day, even if the house is warm. Ours is pretty tiny (and non-EPA) for 20,000 cu ft.PAHS Designer/Builder- Bury it!
Last time I heard a "%" qouted....
was something like windows and doors account for aprox 30% of the heat/cooling loss in the "average" house.
Never was sure if that meant new const .....existing ...or the average combined both?
Either way .....if 30% is leaking thru windows and doors ..that means 70% is leaking somewhere else!
In an old house ...I'd guess choosing between the "better" and the "best" lines wouldn't be worth the exrta cash .....
Just the fact new windows are going in would make worlds of difference.
The theory behind the 30/70% was that money would be better spent sealing up the rest of the house. FHb and JLC have both had articles pointed in that direction.
Jeff
Buck Construction Pittsburgh,PA
Fine Carpentery.....While U Waite
Thanks, Jeff. That's helpful, too.
I should have said this to begin with, but I'm building new.Any jackass can kick down a barn, but it takes a carpenter to build one.