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Old 12-31-19, 06:17 PM   #7
Lurking Renovator
Join Date: Dec 2019
Location: Redwood City, CA
Posts: 5
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@gadget, I'm in the SF Bay area on the peninsula. It gets down to the high 40s F this winter, and I'm expecting more multi-day heat waves in the coming decades.

@JRMichler, thanks for the calculations! I didn't know that before. Very useful!

I think I'll put my money into triple-glazed windows (R9), or even quad-glazed (R17) in one or two places. I will have a lot of big windows but fortunately they face the North-East direction and only get about 1 hour of sun in the early morning. For the windows facing South-West, I'll install external solar shades and pull them down in the summer.

Overall, it sounds like I can just go completely electric for heating/cooling and even have fewer heat pumps (3 x 9000 BTU) given excellent insulation. I'll run two air handlers on one condenser for any pair of rooms that don't usually get used simultaneously, like the "big room" downstairs and the master bedroom upstairs.

Thanks, everyone, for chiming in. I now have the answers I needed!

Happy New Year!
dfhuynh is offline   Reply With Quote