I’m trying to figure out the best way to model a steel stud wall with internal insulation in honeybee.
What’s the recommended approach for representing the steel studs and the insulation? Should I account for the thermal bridges explicitly, or is there a simplified method people usually use?
Hi @ajassoi , there are a couple options that you might decided to utilize, depending on the goal / use / phase of the model, and who you are preparing it for:
Estimate: Steel-studs generally yield a 50%-60% reduction on the resistivity of the cavity insulation. So for example: if you are using mineral fiber with an approximate R-4/inch, just cut that in half and use that for your cavity layer.
Use the AHRAE HoF Ch-27 ‘Zone’ method to calculate the equivalent thermal conductivity of your stud-layer.
Use the ASHRAE 90.1 Appendix A values from one of the tables. I usually use the Table A3.1-4 “Effective R-Values for Insulation/Framing Layers Added to Above-Grade Mass Walls and Below-Grade Walls” values, which isn’t quite right - but is pretty close and good enough for lots of scenarios.
Unless you are doing some sort of compliance model, or the effect of the studs is a core part what you are testing with your models - I’d say you can get plenty close by just applying a 50 or 60% derate factor though.