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Title 24-2022: Dedicated Outdoor Air Systems #112

Closed joesinger12 closed 2 months ago

joesinger12 commented 2 years ago

Add prescriptive requirements for nonresidential dedicated outside air system units.

Dev Team: Assume current DOAS modeling capability (with no enhancements). Assumes no baseline updates (confirm with CEC). Appendix D3: DOAS: Incomplete in CASE report.

Energy Code Section: 140.4(p) Case Report: https://title24stakeholders.com/wp-content/uploads/2020/10/2022-T24-Final-CASE-Report-HVAC-Controls.pdf

Reported by: joesinger12

Original Ticket: cbecc-com/tickets/3322

joesinger12 commented 2 years ago

Applicable sections of NACM with updates for DOAS:

Original comment by: joesinger12

joesinger12 commented 2 years ago

Original comment by: joesinger12

joesinger12 commented 2 years ago

Original comment by: joesinger12

joesinger12 commented 2 years ago

Original comment by: joesinger12

joesinger12 commented 1 year ago

Original comment by: joesinger12

joesinger12 commented 1 year ago

A recommended update for DOAS is:

Add support to define separate OA reset schedules for heating and cooling coils in DOAS with heat pump or separate heat/cooling tempering coils. Currently the set point of the cooling and heating coils can be different, but must be constant (FixedDualSetpoint). With separate OA reset schedules, the SAT could be adjusted (linearly) to better correlate to actual sensible and latent load conditions . For example:

cooling coil control: SAT = 75F at OAT = 75F , SAT = 65F at OAT = 85F

heating coil control: SAT = 60F at OAT = 60F, SAT = 70F at OAT = 40F

Deadband (economizing) between 60 and 75F, including bypass of heat recovery.

This control strategy would shift more load to the central DOAS as it gets cooler or hotter out, minimizing the load on zone HVAC equipment, and for cooling, increase latent cooling as outdoor air temps increase.

Here are a few resources that describes the OA Reset as one strategy used for DOAS: https://www.desert-aire.com/sites/default/files/Tech-Note-DX-DOAS-Control-Strategy-Technical-Bulletin-DA120.pdf

https://www.swegon.com/siteassets/_product-documents/air-handling-units/gold-version-f/functions/_en/gold_f_functions.pdf (see ORS control scheme)

Original comment by: joesinger12

joesinger12 commented 1 year ago

Original comment by: joesinger12

joesinger12 commented 1 year ago

Summary sent to KB on 12/6/22: This enhancement adds SPM:OutsideAirReset to individual coil outlet nodes based on a new enum option, AirSys:ClgCtrl = “OutsideAirResetDualSetpoint”. Currently if AirSys:ClgCtrl = “OutsideAirReset”, an SPM:OAReset is added to the fan outlet node. This new option allows control the heating/cooling coils independently, and the main application for these controls is for a DOAS unit w/ tempering coils. To go along with this option, there are four new HtRst* properties that will be present when this ClgCtrl option is specified. See snipet below of the attached is an example SDD xml with this new option utilized for the AirSys DOAS, and the resulting IDF I’d expect with two SPMs on the respective coil outlet nodes. We will disallow this control to be used if the AirSys does not have both heating and cooling coils, so these coil nodes should always be present when you create the SPMs.

OS translator update: https://github.com/NREL/OpenStudio/commit/1f102db2513c3744e23cc6bfde0a0b49dc7ab8af

Original comment by: joesinger12

joesinger12 commented 1 year ago

Original comment by: joesinger12

joesinger12 commented 1 year ago

Original comment by: joesinger12

joesinger12 commented 1 year ago

Moving to next 2022 release. This capability is included in current OS translator.

Original comment by: joesinger12

joesinger12 commented 1 year ago

Original comment by: joesinger12

joesinger12 commented 1 year ago

Original comment by: joesinger12

joesinger12 commented 1 year ago

Move to 2022 Next since it is not included in v3.0

Original comment by: joesinger12