Comparing U-Value in Ashrae 2019 (SI) and LBT 1.3.0

Hi dear community

I was adapting the U-value factor in the same Ashrae zone for non-residential buildings for walls, roof, floor, and the window between Ashrae 90.1 2019 and what LBT 1.3.0 with climate zone, vintage, and mass inputs give us.
The results were not completely the same, I hope @chris could help me with this.


Hi @Nariman.Rafati ,

The values of the Honeybee constructions look good to me. ASHRAE 90.1 and IECC just say that the U-value of the assembly can’t be more than those specified values and all of the Honeybee constructions look like they are just under.

I should also say that hitting the building code U-value exactly can come with a big risk of not complying with the code since there can be different ways to compute the resistance of air films and other properties that could change the U-value slightly. So you want at least a little tolerance between the value specified in the code and the value you are using in your design.

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Thanks @chris. You clarified it very well.