We have a clinic project that is all electric, and will be submetering to meet the Advanced Metering criteria, but we're not finding clarity on one particular point. We will be submetering lighting, miscellaneous plug loads, fan power (via DOAS unit VFDs) and Heating/Cooling combined (via VRF units). We will carry costing for domestic hot water to be sure, but we don't believe it will be above 10%.
Here's the question - the VRF system does both heating and cooling, and our engineers propose treating it as if it were a packaged unit similar to this reference for thermal purposes:
"Smaller buildings may not have large systems that are easily segregated by function. A common example is a rooftop unit (RTU), a single packaged piece of equipment that can provide the cooling, heating, and air handling but is cost and space prohibitive to submeter. Therefore, metering the entire RTU (or metering each fuel supplying the RTU, if there is more than one) is an acceptable way to achieve this credit. Even though metering the energy usage of each system component of a packaged system is not practical, the performance of each system component should be monitored by the building automation system." (Ref manual p428)
Does this seem like an acceptable level of granularity for this system type? I can't find anything specifically referring to VRF systems.