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Best way to insulate windows and patio doors?


mzaslavsky's Avatar
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03-12-13, 08:54 PM   #1  
Best way to insulate windows and patio doors?

My energy-efficiency audit says that the most problematic area is windows. Unfortunately, I'm stucked with aluminium-framed windows, due to condominium restrictions. Thet are double-paned, but with metal as a "thermal break", so consider them as a single-pane. Changing them to a better ones, but also aluminium-framed, wouldn't obviously give a good return on investment. Auditor suggested to install curtains or shades. Which choice would be more efficient? I'm confused with answers I found in the web since it is hard to say if the question was answered by sales person or not. Among the shades, the honeycomb ones with double cells were highly recommended, but are they really better than good curtains. Or, perhaps, some other choices (possibly complimentary) will be better? If you have recommendations regarding brand/models that would be great! I have a couple of patio doors and ten windows. I'd like to keep them operable, so window films wouldn't work, I think (by the way, is that true or I miss something here?). Ideally, I'd like to have something which works both in winters and summers, but separate things are also fine.

 
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Bud9051's Avatar
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03-13-13, 01:52 AM   #2  
Was the person who did the audit an independent energy auditor or salesperson. There should have been many more suggestions.

Curtains in front of a window will make the window colder (not entirely bad), but still allow inside air to convect behind the drapes, which can allow condensation to form.

Bud

 
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03-13-13, 05:47 AM   #3  
What are the others sugesstions? He didn't mention anything else, except caulking and weatherstripping, but that's obvious and I didn't ask about that here. Yes, he was independent energy auditor.

What's wrong with making windows colder? It is aluminium frame, not a wooden frame - they're much more durable, right?

 
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03-13-13, 08:41 AM   #4  
Hanging curtains in front of windows still allows inside air to circulate in between the curtain and the window. Depending upon the window, inside temp, and inside relative humidity, this can result in condensation on the window and in the worse case ice build up. It is difficult to predict, but something you should be aware of.

Did this energy auditor give you a report detailing what he found or just a recommendation as to what you should do. Without the report telling you how much air leakage, and insulation you have through the house, you received his opinion, and not an energy audit. It is like an eye doctor telling you you need new glasses without the prescription, you can't shop around. An EA is supposed to provide you with the data.
1. CFM50 is your tested air leakage under exhaust pressure.
2. ACH50 is that number converted to "air changes at 50 pascals".
3. Total conditioned volume of home.
4. Wall area and insulation value.
5. Ceiling area and insulation value.
6. Any asbestos, lead paint, or other hazardous materials?
7. Recommended air tightening level and ventilation if needed.
8. Combustion appliance performance, a safety check.
9. Exhaust fans, bath, kitchen, dryer, other, how they perform and how are they installed.
10. Attic ventilation,
11. Basement or crawl space insulation.
12. Infrared inspection results with IR pictures and digital pictures.
13. Moisture issues.
14. Outside landscaping related to moisture.

That is just the top of the list. Calculating the heat loss through the various areas tells you how much potential savings are available. Example, those windows.

If he had provided the total window area and the average insulation value, then he could have said, you are paying $200 a year due to heat loss through the windows. If you replace them with better windows that number would drop to $100. Then you could decide if $4,000 for new windows was worth saving $100 per year. Obviously not. In addition he could suggest curtains and say they will not be as effective as new windows, but you might save $35 per year, but there is a risk of condensation. Again, he would be giving you the data and helping you interrupt the options.

If you didn't get anything close to the above, ask for your money back, IMO. And actually, you should have received a lot more.

Bud

 
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03-13-13, 09:21 AM   #5  
Yes, I've got a report with contents very close to what just mentioned. New windows, for example, would save me $176/year - doesn't worth it, though, yes, it will save more than shades and curtains. Anyway, there were multiple recommendations how to improve energy-efficiency of my home in general, but my current concern is about windows (which perform very poor, according to the report), and the comparison of cellular shades and curtains in terms of efficiency in particular. Audit report doesn't asnwer that question. Any other recommendations are also more than appreciated.

 
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03-13-13, 10:56 AM   #6  
I'm glad you received a more complete report, there are too many fast buck operators out there that do the energy profession a disservice. Aluminum window frames are terrible if they connect from outside to inside. Al conducts 5 times better than steel. In some cases you see the Al frame, but it has a thermal break between the inside and outside. But still cold. If there is air leakage around the window, IR pictures would show that, then removing the trim and sealing the gap could help.

There are two concerns, comfort and cost. If the windows just feel cold and you want more comfort, then drapes all the way to the floor can reduce the drafts. I recently saw a link to an inside storm window, where replacement was too expensive or windows were old classics, but they are still a bit expensive. But an option. I can backtrack if needed.

Bud

 
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03-13-13, 01:16 PM   #7  
The old-timers had a lot of effective technology that we have often let go of.

Window shades can do a bit for energy efficiency, at relatively low cost, and can also block or filter outside light, if you want to do that. Shades mounted inside the window returns are more effective at saving energy than shades mounted to the face of the wall or to the window trim.

But the best cure for window drafts and radiant losses is the 3-layered window treatments that really got to their best refinement in the 1930s. I call the system "Silks, satins and sheers," but that's just because I find it easy to remember that way.

In this system, the curtains rise from the floor, as Bud noted. Above the window, the mounting hardware is covered by a box valence which is closed on top. There are three rods and sets of curtains. the one closest to the window is sheer net or lace. That pair is for privacy, and may not be opened often. The silks are the middle set. These may hang from a traverse rod or they may hang from a stationary rod, be joined at the top, and have tie-backs or wall brackets to hold them open further down. They may be the outermost set in warm weather.

The outermost set in cold weather is the "satins." These are, in fact, most often made of velour or a similarly "deep" fabric. They are mounted on a traverse rod and overlap the inner two sets to return to the wall at the sides.

When all of the curtains are closed, you have a box over the window that is made of, and contains, fabric. A very effective way to add R-value to these holes in our houses, developed before "R-value" was even conceived.

 
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