Hello guys…
I need some advice regarding my modelling for Sefaira simulation purposes.
My building was built with a semi-undermass; part of it is underground and part is above ground. I understand that Sefaira does not require the creation of any underground-level modelling; however, I would like to know how this applies to my situation. What should I do to make sure I need to model it or just leave it and ignore it?
Hi Hepi-
because Sefaira doesn’t support underground walls the bast way to approximate an impact that some of the walls in your building are underground, is to calculate the percentage of the underground wall area to the total exterior wall area and to prorate the overall U value.
Will the prorated U-value go up or down or stay the same really depends on case by case.
Underground walls are usually less insulated as they have a steady and higher temperature of the ground on the other side comparing to the average outside air temperature.
If the percentage of underground walls to the total area of exterior and underground walls in your project is very small, like less then 5%, I would keep and apply the U-value for exterior walls. If the % is higher, I would consider a small reduction of that U-value depending on how much of the underground walls do you have in your project.
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