Infer supply air temperatures for equipment

[pflaumingo]

The supply air temperature needs to be inferred based on the type of equipment that is present in a zone.

1. Discuss in this thread the proposed logic
2. Create an implementation design in the code
3. Write tests
4. Write code

[pflaumingo]

Some of this will be dependent on #27.

[mdahlhausen]

See the standard_design_sizing_temperatures method in openstudio-standards.

Does this include what setpoint managers to assume as well? (scheduled, warmest reset, oat reset?)

I propose:

• Air-based VAV and zone cooling systems: 55°F.
• See the standard_design_sizing_temperatures method in openstudio-standards.

Does this include what setpoint managers to assume as well? (scheduled, warmest reset, oat reset?)

I propose:

• Air-based VAV and zone cooling systems: 55°F.
  • Air loops have warmest reset to 65F (or we could use EMS code to implement ASHRAE Guideline 36).
  • Zone equipment is a fixed set 55°F
• Air-based VAV and zone heating systems: 104°F (matches openstudio-standards). We could drop this to 95°F, as that is typically the maximum reheat temperature.
• DOAS systems: 70°F +-2°F deadband, and ability to drop to 65°F in peak cooling condition. Or base this on an OAT reset. At IG, we also implemented a 'searching' scheme that would update the neutral SAT point every day to minimize fan energy.

I'll read through ASHRAE G36 and see if I can formalize that here.

[pflaumingo]

What's most critical is ensuring sizing is appropriate for sensible and latent loads. I'm pretty sure EnergyPlus ignores setpoint managers and such during sizing so we shouldn't have issue there. The UI for finer tuning of energy models won't be there so as long as we're applying something appropriate it'll be fine. Resetting temperatures is fine provided we don't fail to account for appropriate latent loads. For systems used for total load that reset, how should we control for latent loads? We can use humidistats for some objects, but DX coils don't allow for humidity control. EMS?

For the DOAS system, should we control humidity more appropriately than just a 70F supply temp?

[mdahlhausen]

You are right about sizing not accounting for setpoint managers.

I suppose there could be conditions where latent load drives the sizing instead of sensible load. For the vast majority of systems, 55F cooling supply temperature at design is enough to handle all latent loads.

For DOAS systems, I've seen a 60F dewpoint design temperature. I think I can set controller right after the controller to make sure it hits that dewpoint?

[pflaumingo]

This sounds good to me. Yeh, try with a controller for the dewpoint control as I'm not sure it's doable with a DX coil. I think it may be possible by wrapping a DX:TwoStageWithHumidityControlMode in a coil system.