I think you're trying to tackle a simulation problem that's beyond the capabilities of any ready-made building simulation tool that I can think of, because you're combining very low temperature conditions plus underground heat transfer. There are BES that can cover either of these issues to some degree, but not both! For modeling freezers, eQUEST/DOE-2.2 has a special refrigeration version and maybe EnergyPlus or TRNSYS do too (I just haven't followed them that closely to know). While all three of these programs, especially EnergyPlus with KIVA, can model underground heat transfer but that's only for a building foundation, not an entire structure undergroud! Whenever people mention underground heat transfer, I think of the very long time constants that stretch over years, making it difficult to handle in a typical BES environment. If you're very serious about this topic, I can think of the name of several experts in the field (professors) to whom you might want to ask for advice. Just e-mail me at yjhuang@whiteboxtechnologies,com because I don't want to give out names on Unmet Hours.