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IECC standard reference HVAC system for VRF/DOAS

asked 2022-07-12 12:44:40 -0500

morronini's avatar

updated 2022-07-13 11:37:14 -0500

Hi energy modelers,

I'm building an IECC (2018) standard reference building energy model for a hotel with an air-cooled heat recovery VRF/DOAS system. The HVAC system which I should seemingly use for the baseline model does not make sense to me, so I wanted to get some input.

According to the attached snippet of the "Commercial Buildings - Total Building Performance" section, the standard reference building should be modeled with System 3: VAV/electric resistance heat. However, this doesn't make sense for a hotel, involves a complete remodel of the HVAC, and even requires me to re-model the secondary system (DOAS units), which IECC standard reference buildings don't usually do.

I know there is often leniency in interpretation, so if anyone has experience with this, please share. The ASHRAE 90.1 2016 standard reference HVAC system for a hotel in this climate zone is PTACs, which makes a lot more sense and would use the same DOAS units for the standard reference model. Additionally, if one could interpret the VRF system as "single-zone," then the IECC would require PTHPs as the standard reference HVAC system, which would also make sense.

Thanks in advance to anyone who can help!

Best, David

C:\fakepath\iecc snippet.png

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answered 2022-07-13 11:34:58 -0500

updated 2022-07-14 10:22:26 -0500

Hotels >3 stories fall under Group R occupancy per the IBC. So, you could model the baseline as a System 8 (PTHP).


GROUP R. Buildings or portions of buildings that contain any of the following occupancies as established in the International Building Code:

  1. Group R-1.
  2. Group R-2 where located more than three stories in height above grade plane.
  3. Group R-4 where located more than three stories in height above grade plane.


310.2 Residential Group R-1. Residential Group R-1 occupancies containing sleeping units where the occupants are primarily transient in nature, including:

  • Boarding houses (transient) with more than 10 occupants
  • Congregate living facilities (transient) with more than 10 occupants
  • Hotels (transient)
  • Motels (transient)
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Asked: 2022-07-12 12:44:40 -0500

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Last updated: Jul 14 '22