Tough call, but I?d probably be conservative and err on the side of making assumptions that result in MORE energy consumption in my modeling (unless there is some benchmarking you can compare to).

That means I?d probably assume the walls are exterior and fully shaded. There is a pretty good chance there is at least small dead-air-space between the buildings (even if it is only a few inches), plus you have no control over what is happening on the other side of the wall? maybe the neighboring building is minimally conditioned, or becomes abandoned.

Nathan Miller, PE, LEED AP BD+C ? Mechanical Engineer/Senior Energy Analyst
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