Sill and Grace

Umbra on windows 6

Dear Umbra,

I just bought an old house and need to replace some of the windows. Are there alternatives to vinyl windows that will still cut down on heat loss?

Noah Winer
Philadelphia, Pa.

Dearest Noah,

I hope I've caught you before you've placed your window order, because you are at a moment of opportunity. Window replacement will make a huge difference in your house's energy efficiency. You could be losing up to a third of your heat through those old windows, and I'm sure they're not helping with cooling either.

What a pane.

Here are the basic window-shopping questions: Does your climate require keeping heat out, or in, or both, and which side of the house needs new windows? In light of these concerns, a window's efficiency actually has less to do with its vinylness than with other factors such as glazing, design, and installation. (But don't buy vinyl windows -- ick. Try wood instead.)

First, there's glazing. This refers to whatever material fills the window frame. Usually for us this is treated, coated, or doubled-up glass. Modern glazing does amazing tricks, like letting some types of light rays through and blocking others, or letting all light into the house but only some heat-type rays back out. Double-paned windows have space between the panes, often filled with argon gas, which is a better insulator than plain old air. You may find the potential choices dizzying, but don't despair.

The basic type of window also plays a role. Fixed-pane (non-opening) windows obviously give less opportunity for wind to whistle through than casement (side-hinged) windows. Casement windows, in turn, usually have a tighter compression seal than double-hung windows (the kind with one or two sashes that you lift up and down, found in most old houses).

How to differentiate between all these options? Fortunately, the National Fenestration Rating Council has developed a ratings system. You'll learn all about the numbers relating to energy efficiency: the U-factor or U-value, which measures thermal transmission; the Solar Heat Gain Coefficient, which measures how much sun slips in to roast you; and rankings for condensation resistance, air leakage, and visible transmittance.

It's truly too much to describe in this space. Read about choosing windows on the DOE's Energy Savers website or in the American Council for an Energy-Efficient Economy's Consumer Guide to Home Energy Savings. You are about to spend a chunk of change on excellent new windows, so get the best bang for your buck. And remember to get a good contractor. If your window is clumsily installed, all your hard work choosing the right one is shot.

Defenestratively,
Umbra

Yours is to wonder why, hers is to answer (or try). Send your green-living questions to Umbra.

Umbra Fisk is Grist Research Associate II, Hardcover and Periodicals Unit, floors 2B-4B.

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  1. ktjensen Posted 6:41 am
    12 Sep 2005

    Replace SASH onlyOn my house in Louisville, KY I just replaced the SASHES with a SASH REPLACENT KIT.  It took maybe 15 minutes per window, and cost maybe $60 to $100 per window.  Worked great!!  As long as you have a gneric size window opening (which most people do have, if their house is less than 25 yeasr old).

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  2. kedap Posted 8:54 am
    12 Sep 2005

    replacement windows, of whatever varietythe best advice in this article, in my opinion, is to make sure you have a reliable contractor...and i speak from experience! our window replacement job started early nov. 2004, and it was a quick fix, purely aesthetic indulgence that we thought would get us rolling on the behemoth remodeling project that lay before us. well, the #%@*!? contractor stretched what should have been a 10-12 day job into about 8 weeks, wasn't done with the finishing details by xmas, then the deluge of rains hit so. cal. right after xmas, and we had water running into the house everywhere (never had a leak before this installation)...and now here it is sept. 2005: we have been through numerous discussions with other contractors who don't want to get near the problem, but we may finally have found a good soul who will be coming out this week to start the job all over again (the replacement windows that were installed last year cannot be salvaged...that's how poorly they were installed)...and in the meantime, i've had all the appliances for my kitchen remodel in storage, because of this overwhelming problem! i can't possibly second umbra's advice with too much gusto: get a reputable contractor!!!

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  3. Biodiversivist's avatar

    Biodiversivist Posted 5:49 pm
    12 Sep 2005

    I wonderIn my experience, double glazed windows have a significant failure rate, allowing moisture to get between the panes. When the seal around the perimeter of the two panes fails (and they all fail eventually) they must be replaced to keep their insulating rating.
    http://soundproofwindows.com/dual.html

    http://www.ask-jeff.co.uk/building-double-glazing.htm
    I wonder how much energy is used to make two new panes of glass out of silica? I wonder if anyone has considered the energy consumption caused by the fact that we must now continually replace our windows?
    http://www.bsnglasspack.com/html_gb/le_verre/fabrication_verre_gb.htm

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  4. EnergyGuru Posted 12:03 am
    14 Sep 2005

    Yes, Contractor Selection is KeyAs an Environmental designer/builder & remodeler I am constantly faced with having to tell homeowners that their last guy hosed them or had only half the knowledge he should have, not to mention all the unscrupulous or unreliablity problems I hear about.

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  5. EnergyGuru Posted 12:07 am
    14 Sep 2005

    glazingIn the past the technology was less advanced and premature seal failure was more common.  Nowadays it is rare so don't let that stop you from upgrading windows.
    As far as energy used to make new glass goes, it is not insignificant.  BUT, the energy wasted by not doing anything is much more.  My recommedation is to get SuperWindows that are highly insulating and we won't be faced with upgrading everything all over again in twenty years.

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  6. EnergyGuru Posted 12:19 am
    14 Sep 2005

    The BEST choice is FiberGlass Frame WindowsI put in hundreds of windows every year.  I try to steer all my customers, friends and family to extruded FIBERGLASS windows.  They are way stronger and more sustainable than flimsy environmentally problematic vinyl and many manufacturers can install super-insulating triple pane glass in these stronger frames, whereas that is not even a choice in vinyl and usually not in wood.  Fiberglass frame windows are more expensive than vinyl (worth it) but usually less expensive that wood.  Umbra, please go back and research these type of windows, and update this article - it is a real environmental disservice to leave out the best choice and not discuss the importance of the best insulating glass you can afford.  This is a hundred year mistake people!  Once they are in it can be generations before the cost is justified to change them again.  By the way I like wood as a beautiful second choice, we just have to get the manufacturers to pick sustainably harvested wood.

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