Window choice problem with new Canadian regulations
When I get my current house sold I will be building a 1240 sq ft, single-level house for me and my wife. It will be very close to Passivhaus and also close to Net Zero. I used to build energy efficient houses in Ireland prior to coming to Canada in 2007 and this proposed place will be built similar.
The problem I have is the introduction of new window regulations for BC. I attended a seminar last week in regards to this and, to cut it brief, as of this coming December any window and door fitted into a BC house will have to comply with NAFS 08 and the Canadian supplement. NAFS is supposed to give an overall standard for North America, except it doesn’t! The Canadian supplement will mean more extensive, and expensive, testing. In my eyes this may well prevent European manufacturers of high performing windows and doors selling into BC for Passivhaus construction.
Anyway, in my proposed house I may now have to accept a poorer performing window and pay more for the privilege. I am a certified energy advisor and have modeled the house with the Hot2000 software. This gives a heat loss of around 12000 Btus. However, Hot2000 is not particularly good at modeling windows, although this is supposed to be rectified when the updated version becomes available next year.
Can anyone please tell me just how much of a difference SHG makes between say 0.4 and 0.5 on a 4 ft x 3 ft triple-glazed window facing southwest? Is it reasonably substantial or not, or am I, maybe, making too much of the regulation change?
There is a lot of sun in the area that I will be building in, southeast BC.
Many thanks for any advice.
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