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Modern Window performance?

Post in 'The Green Room' started by wahoowad, Dec 3, 2006.

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  1. wahoowad

    wahoowad Minister of Fire

    Joined:
    Dec 19, 2005
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    1,544
    Loc:
    Virginia
    My 1987 built house still has the original windows. They are aluminum-clad double-paned glass (both windows and sliding glass doors). I have replaced a few over the past couple years because the inner seal goes bad and condensation fogs up the glass. By replace I mean I take them to the glass shop and they put new glass in with a fresh seal.

    I can always feel significant coldness from them in the winter when I approach them. There aren't any leaks around the edges, it is just cold air 'radiating' off them and the aluminum frame. It feels like this cold air then drops down to the floor and generates a cold air movement almost like a leak. I feel this cold air movement but don't find any leaks feeding it, so I assume it is cold air dropping and creating the current.

    I know new windows are much more efficient, but do folks with new windows still feel coldness as they approach the glass or sliding door? Or are they so efficient you don't even feel this? My heating cost in Virginia (via heatpump) is probably ~ $850 (and that might even be a high estimate) so it would take a long time to recover the expense of window replacement. I'm assuming decent windows installed would be over $3000 with a 7 year or longer payback.

    Anybody have new windows lately and have any thoughts to help guide me? I probably need a new heatpump anyway before investing in new windows (original heatpump too!)

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  2. jabush

    jabush Feeling the Heat

    Joined:
    Jan 23, 2006
    Messages:
    385
    Loc:
    Howard County, MD
    I've been systematicallly replacing all the windows & doors in my house over the last couple years. It's made a big difference in heat retention & cooling, especially upstairs.
    I've been using these guys... http://www.baltimore-maryland-replacement-windows-doors-siding.com/ and have been happy so far with the "Preservation" line. Granted these things are pricey, but I look at it as an investment in my home. You could cut the cost almost in half by installing yourself, but you lose the lifetime warranty.
  3. Turner-n-Burner

    Turner-n-Burner New Member

    Joined:
    Mar 21, 2006
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    184
    Loc:
    North of Boston
    I just replaced a few circa 1964 single pane windows with some new Anderson woodrights... last night we had a bit of cold weather, so I checked the temp of the glass... The surface temp of the new window was 15 degrees warmer than one of the remaining old windows... Huge difference!!! but that is comparing a top of the line modern window to a mediocre old window... your difference would most likely be less significant.

    -Dan
  4. kd460

    kd460 Feeling the Heat

    Joined:
    Feb 5, 2006
    Messages:
    394
    I had aluminum windows in my old house. So cold that frost would build up on the frames on the inside! When I changed to vinyl, it was like night and day. No more conduction of the cold, and no more of the "chill" feeling. It made a big difference. The wife was now able to rearrange the furniture so that putting a couch or chair near a window in the winter would not make you cold. We never realized it but, we would arrange the furniture so we stayed away from the windows. After the vinyl, the rooms got larger and more flexability in furniture arrngement, not to mention about 15% less in heat bills.

    I think it was worth the investment. KD
  5. GVA

    GVA Minister of Fire

    Joined:
    Sep 4, 2006
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    2,140
    Loc:
    Waxhaw, NC... Formerly North shore Mass
    Some windows will say double or triple pane but make sure that they have argon in between the panes this helps limit thermal transfer, also aluminium windows radiate the heat out quicker than say vinyl... Wood is best but alot more money but should last alot longer.
  6. Burn-1

    Burn-1 Feeling the Heat

    Joined:
    Jul 13, 2006
    Messages:
    446
    Loc:
    Lakes Region, NH
    Actually the cold feeling you describe is caused by you radiating, (losing) more heat to the colder outside temperature than it is radiating back to you not necessarily a draft. Also as your heated room air hits the colder window, it cools by convection and becomes more dense and falls making a convective current which is again not a draft. You may have drafts to contend with as well.

    I replaced all of the windows in the house we bought with mid-grade vinyl from Home Depot and we use Roman shades at night to keep some of the airflow off the windows. Some are argon filled but the ones facing south are only low-E. for more gain. It made a very big difference in heating bills and overall comfort but I still have the feeling you describe just not to the magnitude as before.
  7. Rhone

    Rhone Minister of Fire

    Joined:
    Nov 21, 2005
    Messages:
    824
    Burn-1 is right, the windows are sucking the heat out of you making you feel cold even if the air temp is comfortable.

    You won't make your payback. Usually the only time it's wise to replace windows is when there's a call to replace them. Maybe you're remodelling, maybe your window has broken, maybe you want the convenience of not having to go up on a ladder to put storm windows on, or want the easy cleaning feature, in my case maybe your window has leaked water and damaged the framing around it. Your windows now are around R2 (U-Value of 0.50), new windows that are reasonably priced (Low-E & Argon) are usually around R3 (U-Value 0.33). They cut the heat loss through the window from 25% to 17%. That's just heat loss, as you've found out newer windows allow warmer surface temperatures so they don't suck as much heat out of you and let you feel more comfortable in the same air temps. I have a program that calculates things like this and plugging in the heating degree days & cooling degree days for Richmond Virginia, a 3x3 window going from R2 to R3, using prices from my area would save me around $6/year in heating & cooling per window. If they're cheaper in your area, and very likely your savings will be even less. But, that's just heat flow, not air tightness or taking into account the warmer surface window lets you feel more comfortable at the same air temp, or the affects of the aluminum frames, and using R2 for the entire window vs. R3. At approx $300/window installed your payback will be over 20 years. If the new windows are more like R4 (U-Value 0.25), it'll be $9/year per 3x3 window or less since I'm pretty sure your prices are cheaper than here. Bang for buck, use your money elsewhere. It's usually replacing leaky single-pane windows with weight pockets in cold climates where the payback is reasonable and difference huge. Your climate being rather mild and your costs for the area low your payback years are particularly long if the reason you want to replace them is for heat savings, and not for the convenience features. Maybe make yourself some insulated roman blinds perhaps, if you add R3 to your current windows you'll save around $10/year per 3x3 window and it won't cost you much.

    *EDIT* If you're going to be replacing the window anyway then the question becomes is it worth paying extra for Low-E and Argon. Building codes may require a minimum, usually it's wise to pay the extra for upgraded windows (Low-E + Argon/Krypton). In my case it cost an extra $28 for the upgrade per window, and each saves me $9/year and the room is a little more comfortable. That was a no brainer, I purchased the upgrade.
  8. Burn-1

    Burn-1 Feeling the Heat

    Joined:
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    Loc:
    Lakes Region, NH
    Rhone is right on the payback. I probably should have added that we put 1.25 inches of foil faced foam around the existing building envelope and installed better attic venting and some blown cellulose. Those made the biggest difference, we did the windows since it made sense cosmetically and financially but they are but one part of a larger system.
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