To get this to work in an URBANopt simulation, I would use the Inject IDF measure to inject the text for the ground temperatures. Here is a sample:
inject_idf_to_urbanopt.gh (91.3 KB)
I can’t think of any situation where a the other side temperature of the ground should be as low as 10C. Even if there were a wall of ice on the other side of it, the warmth of the building would make this much higher. But maybe you’re in a tropical climate and you want to set it to something like 24 instead of 18.