AttachedToSpace w/ multiple adjacent spaces

[shorowit]

Currently you can only attach a surface (wall, floor, etc.) to a single Space through the AttachedToSpace element (Max Occurances: 1).

This has some limitations. Examples:

• A floor between unconditioned basement and living space. Since HPXML does allow both conditioned/unconditioned zones and spaces within, it seems like you ought to be able to attach the surface to both spaces.
• A wall between two conditioned spaces (say, two bedrooms). Some software may want to describe the surface.
• A west wall for the entire home with multiple conditioned spaces (rooms) adjacent to it. Is this a use case we would want to support? After all, you wouldn't know how much of the surface area is attributed to each space.

My recommendation would be to replace AttachedToSpace with AttachedToInteriorSpace/AttachedToExteriorSpace. That would address the first two cases; if we care to support the third case, then we would need to allow multiple of each.