Does energy efficient doors & windows have any impact on energy bills?
Last Post 02 Feb 2019 11:27 PM by davidhopke. 5 Replies.
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LidaUser is Offline
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19 Sep 2018 12:03 PM
"Hi, We're planning to build a new house in the next few months. We 're confused in choosing which type of windows should be installed, as our budget is tight. A window installation and replacement company in Toronto recommended energy efficient windows and doors would be better during winter. Does it have any impact on energy bills?"
Dana1User is Offline
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19 Sep 2018 04:35 PM
Yes it does make some difference in the heating & cooling bills but the particulars matter. Whether there is a financial "payback" depends. An uninsulated 5cm thick exterior door loses twice as much heat as an insulated door. A code-minimum window maybe a third more than a better-grade double-pane or low-end triple-pane. What windows are they calling "energy efficient"??

In many homes windows account for 1/3 of the heat load, but with the right glazing they can still be net heat gainers, reducing the total heating energy use. Solar gain can vary quite a bit depending on which low-E coating(s) it has, and which surface it's located on. For a house in Toronto a dual double-pane with a low-E coating on surface #2 ( the interior facing side of the exterior pane) and a hard-coat low-E #4 (the surface in contact with the indoor air), can perform as well as a pretty-good triple pane without excessive winter condensation. (In Winnepeg the condensation factor would be too much.) But if that's a custom order the upcharge may not pay off.

In colder climates than Toronto there can be a comfort payoff with much higher performance windows, but still not necessarily a financial payoff. A lot depends on what your performance goals are for the whole house. A code-minimum house (= the worst performing house that is still legal to build) doesn't have nearly the performance requirements of a Net Zero Energy, R2000, PassivHaus, or PHIUS type house. It's cheaper to double the performance of the wall & roof assemblies than it is to double the performance of windows, but being selective about what glazing is on which side of the house, and the window sizing can make a difference in the heating & cooling energy use. You don't want massive amounts of high-gain glass on an unshaded west facing wall, or even too much on south facing walls, but even north facing glass can be net energy gainers with the right glazing options.
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20 Sep 2018 08:25 PM
Okay, Dana pretty much spelled it out. Proper window coatings and planning/placement with mid-range windows can yield better results than simply throwing money at poorly planned out high-end window assemblies.

If you're building new, or gutting walls and remodeling, you have choices on spending money on wall performance and window performance.

Basically, try to rule out code minimum for both walls and windows.
And, if given the choice between high/medium performance windows and high/medium performance wall assemblies, much of the time:

High performance walls + Medium performance windows >>>> High performance windows + medium performance walls.

And always, always ALWAYS keep an eye on the bottom line. How much do you expect to REASONABLY save over time, and will the investment pay back. Either monetarily or in comfort factor.
Sure, everyone would LOVE an R100+ in the walls, ceilings/roof and floors and quad-pane windows. But beyond a certain point, the net payback will exceed the lifetime of the product. And beyond a certain level, exceeding code by a certain amount simply becomes means you're using the most expensive fuel of all to keep your house comfortable. Burning money...
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04 Jan 2019 06:59 AM
Some good advice above.

Of course windows and doors make a difference. If we are talking new construction then you’re probably going to put a low-e, argon filled double pane window. Next question is how will they open and where will they be? The biggest energy penalty in a northern climate is glass on the north side. I hate to say this because indirect light can be great but the fact is the most energy efficient thermal pane window money can buy is still not as energy efficient as an insulated wall. Limit glass on the north side. Windows with the lowest air infiltration tend to be in the following order—fixed, casement/awning, single hung, double hung and horizontal sliding.

Meeting egress is easier with casement and horizontal sliding which only comes into play for bedrooms.

Triple pane can make a difference but if budget is tight and maximizing energy efficiency is the priority it’s smarter to put that money elsewhere.
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05 Jan 2019 09:34 AM
Posted By strategery on 04 Jan 2019 06:59 AM
Windows with the lowest air infiltration tend to be in the following order—fixed, casement/awning, single hung, double hung and horizontal sliding.


Big fan of tilt-turns (where they make sense) myself.  And their latching systems generally pull the window in tight to the seals.
davidhopkeUser is Offline
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02 Feb 2019 11:27 PM
Just think about it 10 to 15% of floor square footage should be limit for window openings ie 2000 sq ft 200 sq ft window surface. Windows Standard maybe r4 you now have 200 sq ft of wall surface with only R4 maybe R6 insulation value.
With hopefully the wall assembly in the High 20's R factor. go casement for sealing factor and pony up for highest R value glass budget will allow.
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