High vs Low U-values

Hi all, I have a question about a line in FBC that confused me a little bit...

On page 722 of Fundamentals of Building Construction, it says this "For buildings dominated by wintertime heating, low-e units with high U-Factors (to minimize heat loss) and high solar heat gain coefficients (to promote wintertime solar heat gains) may be selected. For buildings dominated by cooling loads, units with low solar heat gain coefficients (to minimize solar heating) and lower visible light transmittance are used."

So as someone who has done my fair share of energy compliance checks with the Comcheck software, and also from the knowledge I've gathered from other sources, I was under the impression that low U-values were preferred for minimizing heat loss. I can understand why the window units would want a high SHGC to admit in solar heat gain, but why high U-values?

Thanks!

Aleksandar Stojkovic October 11, 2020 18:07

That is odd. It could be that they meant "high performing" u-values (which would mean literally low U-values for the units).

Julie Hagopian October 11, 2020 18:20

That's a good point, thanks. It's a poor way of wording it on their part but that would make more sense.

High vs Low U-values

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