Is Low-E glass worth the cost?

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  #1  
Old 05-17-13, 02:16 PM
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Is Low-E glass worth the cost?

I'm in the process of fixing my 100+ year old double hung windows. Many of the old aluminum storm windows are either completely missing glass and screens or are in such rough shape that the thickest of weatherstripping will probably do nothing. So, I'm in the market for new storm windows.

While I* am concerned about excess heat in the summer, I am more concerned about getting and retaining heat in the winter. I can always draw the shades or even put canopies above the windows for summer. Besides, I'll be down to half a sheet of glass or less in the summer, since I will have the screens open in the summer for airflow.

Concern The First; will Low-E glass cause more harm than good if I'm trying to keep things warm?

Concern The Second; assuming Low-E is not a bad idea, is it worth an extra $40 per window?

Would regular storms with Low-E windows be a better idea? Assuming I can get Low-E glass to reglaze into my sashes?

Should I forgo new storms and just build wooden storms and wooden screens? (while I like this option, the property will become a rental property and I don't relish my tenants doing stupid things while trying to take down the storms or screens)

*I don't care about summer heat, I'm used to it. My fiance is the one who cannot deal.
 
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  #2  
Old 05-17-13, 02:32 PM
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Installing Low-e glass on drafty, uninsulated 100 yr old windows in what may become a rental unit is, IMO, pointless.
 
  #3  
Old 05-17-13, 02:39 PM
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Hey, who said they were drafty?

Most of my project is to get the windows as draftless as possible. (Hard to believe that isn't a word). Putting up new storms is a big part of that. But, I do understand that I could never make it perfect, and the whole point is; even if it's as perfect as possible, is it worth it?

Looks like your vote is "no".
 
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Old 05-17-13, 03:36 PM
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Ha Ha! If you did a blower door test, you would find out exactly how drafty those windows are, despite your best efforts. (see article that appeared in Jan 2010 JLC ) Not saying that the time you've spent doing that isn't time well spent. It's just that old windows are by nature that way. They were designed to have storm windows as a first defense to slow air. If the storm window is open... well, it's like having no storm window at all as far as your air infiltration is concerned.

Bottom line is, you are probably losing so much air (energy) out the windows due to air infiltration that IMO it doesn't make any sense to try and SAVE energy by adding low-e. When air conditioned or heated air leaves the home out the leeward side of the house, fresh air comes in to take its place, and that air has to be cooled/heated, and around and around it goes.

If a person was putting in new windows with better weatherstripping and air (wind) resistance, and was going to air seal the perimeter of the frame so that less air could come through the rough opening around the jamb and trim... then it would make sense to pop for the extra $$$ for low-e.
 
  #5  
Old 05-17-13, 03:48 PM
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If this house is something you would like to own for the long term and rent to a good steady tenant, then comfort and energy efficiency are important. I hear many complaints about tenants having to pay high heating costs and thus they move on as soon as possible. Even if you pay the heat it affects what the rent has to be.

As for the low-e, there are different levels to select from: Window Ratings - Energy Ratings

Bud
 
  #6  
Old 05-17-13, 04:08 PM
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Low E glass has nothing to do with eliminating drafts!!!

It is a way to turn a window (really a big hole in a wall) into something a little bit better when it comes to insulation. Even with E-gas, the "R-value" of the window will still be no better (or even close to) a 8" uninsulated concrete block wall, except that a block wall is better a night when it comes to radiant heat loss. A sheet hung up at night is many times better than Low E glass, as everyone knows at night in a cold climate.

No matter how wonderful the window may be, if it not installed properly the infiltration will be costly in terms of heat loss/gain. If not installed with proper flashing, any moisture getting into the fiberglass insulation can reduce the insulating value of the wall area by 50%.

Dick
 
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Old 05-17-13, 04:51 PM
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Low E glass has nothing to do with eliminating drafts!!!
My point simply was that the money put into adding low-e would not be a good investment. Similar to someone having low-e glass, but then leaving the window open. What good would that do? (That's an exaggeration, obviously!) But the two different things are certainly related.

If low-e costs $40 more a window, it might be worth it if the window is tight and you are really realizing 100% of the benefits of the low-e glass. But if the window is drafty, are you really getting 100% of that value? Don't think so. Any energy you might be saving in one respect is still blowing out the window in another. Which is why i would say it's a bad investment.
 
  #8  
Old 05-18-13, 06:29 AM
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As a landlord I would not install low-E windows on a rental. On my properties I have at least a dozen broken windows per year and of course the tennant rarely admits to breaking the window so replacement cost is an issue. I even try to avoid basic thermal pane windows as traditional single pane windows and storms are easier, faster and less expensive to repair. All thermal pane windows require a special order for replacement.

I have low-E windows on my home. In the past 11 years I have discovered one panel that had the glass installed backwards so the coating was on the outside and oxidized. And I've had five panels leak causing the coating on the inside to oxidize. So, if you do decide to go that route carefully research the warranty and document your windows well and keep your paperwork. The stickers labeling windows get removed or fall off over time so you will need to be able to specifically identify each window to be able to order replacement panes.
 
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Old 05-18-13, 08:23 PM
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Definitely not worth it. Use the 3-layer drapery trick that's been effective for centuries - "sheers, silks & satins" - and save the historic glass.

Sheers, silks & satins can be read as sheers hung on a straight rod close to or within the window casing, silks on a straight rod with tie-backs, and satins (actually velours) hung on a traverse rod under a closed valence.

In summer, many folks take the heavy drapes down and clean and store them.

Want more help maintaining the temp? Hang a window shade inside the casing, then do the three drapes in front of that.
 
  #10  
Old 05-19-13, 08:20 AM
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Thank you, Nashkat1. With the cost of storms, I don't think that expensive drapes are in the future. And since we hope to be out of here in a couple years, I doubt that we will get any for here (other than the insulated/darkening ones we already have). But I will certainly take that advice when we move to a more permanent house.

On that note, six of the largest storms I need will total about $1,000 for Larson gold with flush mount from Big Orange. Not great, but not awful. Debating on if I want full screens so the upper sashes can be lowered for venting. Sadly, that "upgrade" costs quite a bit and the screens are not removable.
 
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Old 05-19-13, 11:29 AM
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There is a reason that the top sashes are always painted shut / stuck shut on double hung windows. No one ever opens them. I would suggest half screens on your storms.
 
  #12  
Old 05-19-13, 11:54 AM
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I see your cause and effect the other way. Nobody opens them because they are always painted shut.

I know it makes more sense to keep them painted shut, but I will get a much greater sense of accomplishment by actually bringing the windows back to their days of glory.
 
  #13  
Old 05-21-13, 04:02 PM
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There is a reason that the top sashes are always painted shut / stuck shut on double hung windows.
I do, often. The most effective way I've found to quickly cool a house is to lower the upper sash on the upper level and raise the lower ones on the lower levels.

I also like to open both sash a bit sometimes just to create circulation in a room. Opening lower sash without opening upper ones also is, IMO, just an invitation to noise and dust.
 
  #14  
Old 05-21-13, 04:05 PM
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I don't think that expensive drapes are in the future.
They've never been in mine!

All of miy drapes come through my sewing machine from the fabric store. Often from the remnants table.
 
  #15  
Old 07-31-13, 05:00 PM
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Here's a good study that I came across while wondering the same as you, Michael.

http://web.ornl.gov/sci/buildings/20...DFs/22_New.pdf

The short answer is yes, low-e glass is worth the cost.

According to the study the payoff for low-e glass storms is about five years, compared to 10 years for conventional glass storms. That figures a $20 premium per window for the low-e.

Hope it helps.
 
  #16  
Old 08-01-13, 06:09 AM
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Thank you, madhatter. I had seen that report and, while it is well written, I feel the experiment was not performed completely. The test appears to have been done over a course of weeks in several houses and sometimes different windows inside the same house. A more telling experiment would be the same house for a year with just windows, and then that same house for a full year with storms. The experiment also did not take into account the summer months (at least from what I could see). As I do not have AC, I would be taking the storms out in the summer, thus losing the low-e benefit, and relying on screens for ventilation.

Given that the premium for low-e on the storms I am considering runs over $50.00 per window, the study's findings are not as applicable. Personally, I think that replacing my sash windows with low-e and using normal glass for the storms would be the best option. However, that would involve paying to replace glass that otherwise does not need replacement, and a low-e/normal glass combination that is untested. But, I have enough damaged glass (and am damaging more in stripping my windows) that I can glaze some low-e in a couple of my sashes to see if there is a noticeable difference.
 
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