Facility Total HVAC Electricity Demand Rate and IdealLoadsAirSystem
Hi there,
I have an IDF that uses IdealLoadsAirSystems (in multiple zones). I read that the electric energy of these systems is not measured. What measurements is "Facility Total HVAC Electricity Demand Rate" giving me then?
I am trying to optimize the energy consumption. Do I look than rather on the "Heating:EnergyTransfer" metric? Is it even possible to optimize energy consumption when having IdealLoadsAirSystems?
Thanks for your help!
To be clear : Your IDF holds IdealLoadsAirSystems only, and this output variable gets automatically added? And it holds a non-zero value for the run period? I just ran this 5ZoneNoHVAC model (ideal loads only) using OpenStudio 3.8.0 (E+ 24.1). That output variable doesn't get added to the in.idf file, although available in the .rdd file. If one were to add PV generation (i.e. not HVAC) though, that output variable would get added by default, I believe.
@Denis Bourgeois thanks for your answer. I might have been not fully specific here: I have no HVACs but the IdealLoadAirSystems and an exhaust Fan (Fan:ZoneExhaust). I do not add the output variable "Facility Total HVAC Electricity Demand Rate" in my IDF. Instead I request it in EMS using Python.
@sz1980, thanks for the clarification. So you requested that output variable in your EMS bit, and it's returning a non-zero value? Any chance this value matches the fan exhaust electricity use?
@Denis Bourgeois It might match this. How can I measure this electricity use explicitly in EnergyPlus?
Add the Fan:ZoneExhaust "HVAC, Average, Fan Electricity Rate" output variable. Make sure the .rdd lists both output variables (both in W), and that they're reported in the .eso file for each time step. It should be apparent in the .eso file if they match. You can always consult the .sql file with DView, for instance.