Frequently Asked Questions (FAQs)

Louvers are best treated as un-insulated portions of the wall. You can add them as a separate wall type (for example, if they are metal, metal building would probably be most appropriate) with no insulation but a wall area. COMcheck will do the area-weighted averaging for the opaque wall to calculate the overall U of the opaque wall. The impact of having an uninsulated wall area is that you will be required to “make up for that” in some other portion of the building envelope. This may mean more insulation on the rest of the wall, better windows, or more roof insulation.

Note:  There is an allowance for up to 1% of wall area in “recessed equipment” in walls in Standard 90.1 if 90.1 is the code in which you are complying with. 

The IECC addresses mixed occupancies by stating that commercial occupancies must comply with the commercial portion of the code and residential occupancies must comply with the residential portion of the code.  

ASHRAE Standard 90.1 addresses high-rise residential and all other commercial buildings.  Residential spaces are those used primarily for living and sleeping and include dwelling units, hotel/motel guest rooms, dormitories, nursing homes, patient rooms in hospitals, lodging houses, fraternity/sorority houses, hostels, prisons, and fire stations.

COMcheck computes an envelope index that is a reflection of the difference between a 'design' building energy performance factor (EPF) and a 'code' or budget building EPF.  The total building load (made up of cooling, heating, lighting, and miscellaneous plug load) is determined by the location you are in, the specific assembly and building types you specify, and internal gains from lighting and miscellaneous plug loads, and of course the thermal properties and orientation of the envelope assemblies. The methodology used to determine EPF is provided in ASHRAE 90.1 Normative Appendix C: Methodology for Building Envelope Trade-off Option.

• Copies of the International Energy Conservation Code (IECC) can be purchased from the International Code Council website.
• Copies of ASHRAE standards can be purchased from the ASHRAE website.
• For codes specific to a state or municipality, contact the authority having jurisdiction.