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swanny
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Posts:4
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| 04/16/2009 12:10 AM |
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New guy here. I have a house, built in 2007 with double-pane clear glass. There doesn't appear to be any low-e coating / argon inside. We're talking basic, clear glass PVC windows throughout the house. Location is Saskatchewan, Canada, it gets COLD here in the winter!
As an aside, our HRV was not working right last winter and there was a crazy amount of condensation on the windows, so much that we put that shrink plastic over the windows. That worked very well. Anyway, the HRV is fixed and so I don't expect that problem next winter.
Anyway... I'm pretty energy conscious. I know my double-pane windows aren't all that effective at stopping heat transfer, they're cold to the touch in winter.
I am wondering if it's worth it for me to replace the windows with triple-glaze low-e/argon top-of-the-line units since my existing windows are only 2 years old? On one hand it seems wasteful to replace fairly new windows, however over the long term the savings in heating the place may pay for them. FYI, I have a 91% efficient natural gas (Armstrong) furnace.
Also, if I do decide to upgrade the windows, should I put them on the North side, South side, or both? I'm reading stuff on the net that suggests I should have the most efficient windows on the North side of the house, and possibly not have the low-e coating on the South windows. In fact, the NetZero house in Edmonton uses 4-pane glass on the North facing windows. I'm not that hard-core, after all I have just R-19/R-20 in the walls (2x6 wood frame construction, basic builder house).
Thoughts? Opinions? Comments? I'm open to all ideas on this.
At some point in the next 5-10 years I would like to build my dream home (solar, GSHP, double stud exterior walls, etc.) but for now I want to make the best of my current home. And besides I really have no idea how long I'll be in this house. It could be 3 years, it could be 30.
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swanny
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| 04/16/2009 12:36 AM |
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Just to clarify... when I mean "is it worth it", I'm not talking about cost, I'm talking about the difference in R-value (bang-for-the-buck). I'm not overly concerned about the cost, I am concerned about having an efficient house, or making the best of this basic-built house.
I'd hate to drop thousands of dollars on new windows and not feel a difference in the winter. |
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Jesse Thompson
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Bruce Frey
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Posts:272
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| 04/19/2009 11:08 AM |
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Are you sure they are not low-E or Argon filled? You can't tell by just looking, although coated glass will have a slightly different reflectivity than uncoated glass if they are side by side. I am skeptical that a house build in 2007 in Saskatchewan wouln't have at least one of those features.
Look for a label and check with the manufacturer.
What is your % of glazing on each elevation? If you have a lot of windows, it may be worth replacing them IF they are not low e or gas filled.....otherwise I would consider storm windows. You should consider the economics of resale and the fact that you plan to move in 5-10 years.
Bruce |
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swanny
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Posts:4
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| 04/19/2009 2:53 PM |
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Bruce, you clearly haven't heard of my builder (I won't mention his name here but he cuts corners, let's just say that, I learned that after I bought the house). That's a whole other story....
There is definitely no coating on the outside of the glass. The house next door has the coating, so it's easy to compare.
We only have one large-ish window facing South. The rest is the front door and the attached garage. So we have little South facing windows as a percentage of the floor space (it's a bungalow). I'm not positive they're *not* filled with gas, however I can see the threads of a screw in one corner. I think that's due to the grill / grid inside the two panes of glass. |
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aardvarcus
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Posts:176
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| 04/20/2009 1:07 PM |
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| I would try to incorperate some kind of storm window with argon and low-e before I ripped out almost new windows. I have seen where people bought some replacement style windows that slip into openings and added them to the inside of their existing windows for a high R low cost solution, but I personally would think you could find some good storms to accomplish the same thing. |
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greentree
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Posts:104
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| 04/24/2009 8:15 AM |
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As an example, a brand of windows puts out a vinyl dbl hung in clear glass with a U .49 or R 2.04, the Low e Argon glazing in the same series is U .32 or R 3.13 So its a 53% increase in R-Value but the improved R-value is still so low your net energy savings wouldnt touch that.
Thermotechs website throws out a figure for a 9-18% reduction in heating costs of a standard to low-e argon. So say you hit 18% reduction on a $1000 bill and saving $180 a month, now divide that by the cost to buy high performance windows and have the new construction windows replaced with new construction windows, re-doing siding and exterior and interior trim. You will be in the ground before that pays for itself. I would go the storm route. |
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Dana1
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Posts:702
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| 04/24/2009 4:00 PM |
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What Bruce Frey said- it's almost never cost effective to replace double-pane windows from a fuel-savings POV, but adding exterior or interior storms can be.
R20 2x6 construction with no foam board for thermal break only has clear-wall (= a wall with no windows or doors or other extra framing) values of about R17-18, and a whole wall (with the more thermal short-circuits from the framing for windows, doors, fire-stops, etc) of about R14. (Source: http://www.ornl.gov/sci/roofs+walls/AWT/InteractiveCalculators/NS/Calc.htm )
Is 2x6 with no foam sheathing still the standard in Saskatchewan? What's the attic insulation like? Or the basement insulation?
You may get much better reduction in fuel use per capital-dollar spent going with interior-storms, high-quality exterior storms, and/or some spot upgrades on insulation where it's cheap & easy. Whole window replacements tend to be a pricey upgrade- sometimes even $olar can be a better value if the windows you have are in good shape.
An energy audit with infra-red imaging, blower-door infliltration testing, and pressurized duct loss testing might find number of better bang-for-buck upgrades, (maybe small, maybe large.)
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swanny
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New Member
Posts:4
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| 04/24/2009 7:53 PM |
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FYI, 2x6 no foam construction is the norm. Basically from the outside in you have siding/stucco, then tyvek house wrap, then OSB, then fiberglass batts, then 6 mil vapour barrier/poly, then drywall. Done. On cold mornings you can see the frost lines out the outside of the house and you can clearly see where the studs are behind the stucco, 16 inches apart. Clear energy losses there.
My next house will have walls at least 8 inches thick (possibly double 2x4 walls, whatever meets code).
The basement walls are 2x4 construction, batts, so R-12 I think that is. And the joy is I hear fiberglass loses it's R-value fast. There are days that are close to -40 so I'm sure I'm not getting R-19, R-12, etc all the time!
As for attic insulation, "code" is R40, although mine is less than that due to settling. I plan on getting the insulation guy back here in the next month or so to up that to R50 (cellulose loose fill).
FYI, I believe with the window style I have you can just replace the lites (panes of glass, sealed unit) without removing the frames. So the PVC window frame stays in the wall, just replacing the glass (going from 2 to 3 panes, or whatever). So no need to touch the siding, interior trim, etc.
I haven't called anyone locally yet, I was thinking of contacting a glass shop to check on pricing. I think I could go from dual to triple pane windows for $5K or less, and probably not need storm windows. Storm window inserts wouldn't work on the main living room window anyway (it's biggish).
I know the home energy audit is available, but for $150 I feel it's not really worth it at this point. I have a high efficient furnace (pretty high, 91%), new doors/windows, good sealed house, I'm upgrading the attic insulation, my appliances are all new (most if not all are Energy Star) from 2007, so there's not much more to gain from an audit. |
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ecobuilder
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New Member
Posts:86
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| 04/24/2009 11:31 PM |
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Insulated window shades would be my suggestion. You can get them up to R-4 or 5 and you have control over your R-value. If you want less just open them and let the sun in, they also work well at reducing cooling loads, althoughI am sure that isn't a big issue in Canada. Much better R-value than even the triple paine windows. I personally have found that triple paine windows are not worth the cost, at least not to me or my customers. I would much rather have a great shade over a good window than spend twice that on a great window.
Tom Pittsley
ecobuilder@aol.com
www.eebt.org |
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"Don't be afraid to go out on a limb. That's where the fruit is." Jackson Brown |
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Dana1
Registered Users
Advanced Member
Posts:702
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| 05/04/2009 10:42 AM |
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Posted By swanny on 04/24/2009 7:53 PM
I know the home energy audit is available, but for $150 I feel it's not really worth it at this point. I have a high efficient furnace (pretty high, 91%), new doors/windows, good sealed house, I'm upgrading the attic insulation, my appliances are all new (most if not all are Energy Star) from 2007, so there's not much more to gain from an audit.
Sure, you've covered the dead-obvious, but a energy audit with a full blower-door and infra-red imaging will find all of the OTHER stuff that is difficult/impossible to see.
With eyeballs alone you'll never find the 2" gap in the insulation at the top of a stud cavity here, the compressed insulation behind a wiring run there, the insultion gaps in mini-framing cavities that couldn't accommodate fiberglass (but could be retro-injected with cellulose or foam), and myriad air leaks @ breaks in the vapor/air barrier at wiring & plumbing penetrations, etc. Unless the place was foam-sealed at construction it's very unlikely that it's at tight as it could be, and odds are better than that you're blowing way more than 10% of the fuel bill on stuff that could be cost-effectively fixed.
An audit that just eyeballs the construction and reads the labels/specs on the equipment isn't what I was referring to. Sure, fix the obvious, but some judicious detailing based on defects discoverable via blower door pressure testing & infra-red imaging can be VERY cost-effective.
If they're capable of pressure-testing & seal the ducts, that can be a big winner too- a 91% efficient furnace that's blowing 15-40% of the air somewhere else isn't really operating anywhere near it's rated efficiency in-system. Pressure testing and sealing ducts on new & retrofit construction to a fairly low maximum leakage level is required now as part of California Title 24 efficiency code, based on field data showing just how LEAKY most duct construction is. If all seams & joints are mastic-sealed & taped you're probably good, but that wouldn't be typical modus operendus from even a middle-of-the-road contractor (let alone a cost-cutter) unless it's specifically called out in your local building code.
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