What Really Counts as Glazing, Anyways? (EEDS SB-12 Work)

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Posted by: from Ottawa
1/12/2021 at 12:25:55 PM

Good afternoon all,

I apologize if this is a silly question, but I am in the midst of completing an Energy Efficiency Design Summary form for a client's new build, and did a quick study of our elevations and found that we're in excess of 22% glazing, which means complicated and expensive studies and simulations that neither of us want to pursue, unless we really need to.

That being said, would the entire opening of an exterior wall be considered as glazing (despite the frames being thermally-broken and rather great at insulating) or, more optimistically, is the physical lite (the glass, itself) the surface area that needs to be considered?

I previously counted the whole opening (frame, but not casing) as the glazing, but this might be generating a far more pessimistic value than necessary.

Any help here is deeply appreciated- I tried scouring through the OBC to see what definitions are there, but nothing immediately clear pops out at me- again, please pardon me if this is really obvious.

Thank you all for welcoming me to the community- I hope to stay a while! :)

Warm regards,


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Date/Time1/12/2021 at 5:42:38 PM

Hi Cory,

I hope to find you well. These are actually really good questions. here are the answers to your questions. Also, I am a building Envelope Engineer. if you need, you can call me at 604-306-7505. we do a lot of Building Envelope repair and upgrades.

1) Yes, the entire window is considered including the frame and glazing when you talk about the RSI values.

2) Its not that expensive if your glazing is beyond your allowed 22%. you need to use a trade off method. you will need an energy modeling to be done for the property. basically it means you will need to increase R value on other areas in order to obtain the same results.

3)I do not have the license to practice in Ontario and the information I provided is based on BCBC code. however, majority of codes follow the NBC and are fairly similar in contents.

I hope I could have helped. but do not hesitate to call or email me if needed.


Iraj Manshadi

Smartco Construction Inc.

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