We have added a new document to the resources page for calculations needed for the Department of Energy (DOE) Energy Star and ZERH programs.  Both programs reference the 2021 or 2024 Energy Code for the Insulation Envelope. Since the EcoSmart™ Stud (ESS) wall is not a Continuous Insulation (CI) wall assembly the 2021 and 2024 Energy Code requires an extra U-Factor calculation to be done. You need to be less than U 0.045 or above R-22 effective insulation for the exterior wall.

Using the 2×8 ESS the calculation is easy.  Any combination of insulation and ESS stud is lower then U 0.045. For the 2×6 ESS wall system with 1″ of closed cell 2 lb spray foam (SPF) the entire calculation will have to be done since it’s just below the requirements.  Generally when you add in the OSB, sheet rock, building paper etc.. to the calculation you add another R 2-3 to the assembly so there is no problem for the the 2×6 ESS to exceed the needed U-0.045.  Notice all the approved CI wall systems do not meet to U-0.045 requirement without all insulating components of the wall calculated in. For all those Passivhaus people out there you will want to be looking at using the 2×8 ESS. That is above the rating for the British Columbia Passivhaus requirements for exterior walls.

Since we are a DOE IMPEL 2023 cohort I tossed in the Embodied Carbon calculations for just the main insulation elements of the wall assemblies for good measure using the most common material used by contractors.  For the all foam products I used the HFO blowing agent information since the HFC is pretty much phased out, but always check your materials! Embodied Carbon is becoming a bigger issue when designing residential homes.

Next week we will dig into costs and potential saving when using the ESS with these programs. That will be an eye opener!  If you are a builder I would suggest getting signed up for the DOE Energy Star and ZERH programs. Check out the EEBA website for more information. You can also go to the ENERGY STAR website for more info and the ZERH website.

Till next week, Cheers!