Heating and Cooling Loads - Below grade level

[FADICD]

Hello,

While calculating the heating load for a given project, using Revit MEP 2010, we realized that Revit does not calculate the heat losses (or heat gain) through the perimeter of the foundations (walls and envelope below grade level). Is there a way to complete the calculation   or the Revit MEP is supposed to be used for a quick (not a detailed and accurate) estimate? Thanks in advance

[HVAC-Novice]

you should not use Revit beyond schematic design for load/energy calculations, it isn't made for that.

Even when you import gbXML into Trane Trace, you need to manually deal with the below-grade wall. For example if your 8' wall is 4' below grade. You technically could create 2 "spaces" (below 4', above 4'), but this may have other problems since the "spaces" fulfill other functions and having 2 in one room isn't good.

i had talked to Trane Trace support on that and htey said they are aware of the issue and working on resolution (for importing). If they ever have a solution, it probably won't right right away anyway and you still manually check.

thsi may be off-topic, but the same holds true for the shared walls between zones. gbXML truly carries them over to Trace, but it also carries over shared walls that don;t exist, or splits them up etc. Needs manual cleaning up.

[ArynBergman]

You shouldn't use the built in Revit load calcs at all.  There's some serious issues that can give you highly inaccurate results.

Your best best will be to trace your model utilizing the guidelines established for building energy models and do an gbxml export to Trane Trace700.  You can also bring your model into DesignBuilder, but I do not have a lot of experience with doing load calcs that way.  And no you can't just use the architect's s model nor can you simplify an arch's model to use as it will still give you problems that will take a few years off of your life trying to identify what they are.

Also update to at least the 2013 version otherwise, you're going to have some headaches that nobody will be able to help you solve.