I don't do a lot of heat-loss calculations, but those I do, I want to do well, and I want to be able to explain them to 'civilians'.
For the first point, whenever I enter data into HVAC-Calc, or Hydronics Design Studio, I fear (often correctly) that I've mis-measured a wall or window, or forgotten some element entirely. A simple triple check calms that fear, but makes me wish the applications could show a 3-D view of the building, with color-scaled elements to show where the heat-loss is greatest. Not only would it help the designer/data-entry-drone, but it could be used to show the homeowner where the best opportunities for envelope improvement were.
Anyone seen anything like this? Or have the chops to write it? [I sure don't....]