COMcheck issue-Building Envelope vs Lighting

[Ken Williams]

Working with the 2015 IECC (3rd printing).

I am trying to run the COMcheck on a metal building (apx 9100 SF total). We have 1658 SF in offices, etc with 8' ceilings. That is the Thermal Building Envelope (conditioned space). If that envelope is the only one entered, the Envelope works out fine. However, I have to enter the remainder of the metal building (7442 SF) in order for the Interior and Exterior Lighting to be accurate. At that point, COMcheck requires me to enter the rest of the building in the envelope (as a separate area) to accommodate the Lighting. When it's entered (and it is semi heated space- Auto repair bays with unit heaters- I have considered it unconditioned space) the Lighting and Mechanical are all fine, but the envelope is 500%+ over budget. Any ideas how to separate or enter this in such a way as to satisfy the requirements?
As a note, all metal building walls and roofs have an R-19 Liner (listed in "cavity insulation"). Any assistance would be greatly appreciated.

 

[JBI]

Looking at the definitions in the (unabridged) 2015 IECC... There is no definition for 'semi-heated', but the definition of conditioned space does indicate that the shop areas with suspended heaters would qualify as 'conditioned space' (see last part of definition - "... or other sources of heating or cooling.").
Beyond that you'll have to wait for someone more adept with COMCheck.
Keep in mind that COMCheck is an alternative prescriptive compliance tool that allows limited trade offs, and may not be useful for every project.
Just saying...

 

[RLGA]

I agree with JBI. If the building complies with the prescriptive requirements of the IECC, then going through the COMCheck process is a big waste of time. If I know I have areas of a building that do not comply with the minimum requirements and other areas that exceed the minimum requirements, then COMCheck will allow one to analyze the entire building envelope to see if the building performs at or better than what would be achieved if the prescriptive requirements were only used.

 

[steveray]

Prescriptive insulation and X fixtures times Y watts / sqft = watts per sqft should be pretty basic....Without getting into any of the HVAC that is....

 

[Ken Williams]

Your advice is greatly appreciated. After playing with the COMcheck some, got is down to 58% over budget on the Envelope. Had to make the roof structure insulation an R-30 even though COMcheck states that an R-19 is the max you can get credit for when you enter a value there.

JBI- The "Semi Heated" reference came from a Comcheck FAQ. I couldn't find an IECC 2015 reference to it either. I'm not sure that COMcheck is the answer on this one. However the plan review person involved is asking for one. I am going to look into a performance based review method instead.

FYI- I have been outside this field for a while and am coming back in part time to assist a friend. Please excuse my lack of knowledge. Our area just recently adopted the 2015 IBC.

 

[JBI]

Ken, I think the plan reviewer doesn't understand what he's asking for...
COMCheck is an alternative method to demonstrate compliance, not a requirement.