Address energy outside of an HVAC season or during unavailable period

[shorowit]

We currently throw this warning: "It is not possible to eliminate all HVAC energy use (e.g. crankcase/defrost energy) in EnergyPlus outside of an HVAC season."

Now that our defrost model is EMS-based, it seems like we should be able to address that one.

In addition, since the crankcase model is so simple, we could consider moving that over to EMS so that we can similarly handle HVAC seasons.

cc @joseph-robertson

[shorowit]

Also look at pan heater usage.

And there is a separate warning related to unavailability periods (e.g., power outages): "It is not possible to eliminate all HVAC energy use (e.g. crankcase/defrost energy) in EnergyPlus during an unavailable period."

[joseph-robertson]

It looks like pan heater is already addressed?

[shorowit]

Looking into this a bit deeper, I think it's a nuanced. Here's when I think we should model various energy uses:

	Outside HVAC Season	During Power Outage
Crankcase heating energy	Yes [1]	No
Defrost supplemental heating energy	No	No
Pan heater energy	Yes [2]	No

[1] Crankcase heaters basically run continuously, even when the unit is off, so it should not respond to HVAC seasons.
[2] If the pan heater control type is continuous, it should probably still run outside the heating season. For any other control type, I believe it already doesn't run outside the heating season.

So I think the only change we need to make is:

• Crankcase heating: Disallow during power outages using EMS. (Continue to allow outside HVAC seasons.)
• Defrost supplemental heating energy: No change needed.
• Pan heater energy: No change needed.

I don't know why we have a note about not being able to eliminate crankcase heating outside HVAC seasons, since I don't think we should eliminate it outside HVAC seasons. I also think the note about defrost is out of date and does not reflect our current model.

We could also consider moving the DHW parasitics to an EMS program so that we can similarly remove that warning.

[jmaguire1]

Would having a schedule for DHW parasitics (thinking about how I just requested one for deadband) be a more elegant solution here than more EMS? If so we could add this to that request and explain the different use case for it, but mechanically I'd think it's pretty similar to implement.

FWIW everything else you suggested looks reasonable to me.

[shorowit]

You are certainly welcome to request these things for E+, but they may never happen (say an E+ developer doesn't want to make the inputs more complex for an uncommon use case, or it isn't seen as a high priority) or it may be a while before it happens.

That said, our constant desire for schedules in EnergyPlus made me file a more general feature request: NatLabRockies/EnergyPlus#11403

[jmaguire1]

I just wanted to (for once) suggest a way around EMS. I like your more general request, because yeah that really encompasses a lot of our asks and feels like we could then talk about which specific things we'd want that to apply to so I'm not going to put in an additional niche request for this one. In general for this when I've needed to I just postprocess out the parasitics in this case.