Support commercial water heaters

[shorowit]

Closes #333.

Conventional storage and instantaneous commercial water heaters

• Replaces StandbyLoss with StandbyLoss[Units]/Value to support different units (F/hr, %/hr, or Btu/hr). This is a breaking change.
• Already has a ThermalEfficiency element.

Heat pump commercial water heaters

• Adds a HeatPumpCOP element.

[shorowit]

Multiple votes for using fraction instead of percent.

Consider a max limit (e.g., 0.1?). Edit: It's not possible to include a max limit in the XSD because it would not work for other units (F/hr or Btu/hr).

Otherwise HPXML WG was okay with these changes.

[nmerket]

🎥 Discussion in HPXML Working Group Meeting 2022-08-09