Walkout basement BEopt

answered 2020-04-07 09:25:17 -0500

shorowit

10881 ●180 ●9 https://www.nrel.gov/b...

Correct, BEopt cannot explicitly model walkout basements. The best approach is:

Increase the above-grade wall height to approximate the total above-grade wall area (i.e., living space + above-grade walkout basement wall area).
Reduce the basement height to approximate total below-grade wall area.
Adjust the above-grade and below-grade wall insulation levels.

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Thanks for the response, Scott. A couple of follow up questions:

Can one adjust the foundation level height above/below grade?
Is there any way to assign specific R/Uvalues to specific sections of the enclosure, or is it entirely fixed as appears to be the case (ie, all fnd walls are as prescribed in the characteristics on the Options tab)?
Is there any report that shows a description of assembly Uvalue, including soil characteristics?

cmctaggart ( 2020-04-09 08:52:23 -0500 )edit

Here are my answers to your questions:

The foundation height above-grade cannot be changed, but the below-grade height (simply called Height) can be.
The foundation walls indeed all share the same insulation properties as specified on the Options screen. 
It is not possible to obtain an assembly U-factor that includes soil characteristics because BEopt/EnergyPlus never calculate such a value. Rather, BEopt uses a 2D finite-difference foundation heat transfer model to account for the effects of soil.