[Equest-users] exhaust heat recovery system with PTAC in eQUEST

[Bishop, Bill]

Hi Sunayana,
Use Pkgd Single Zone (PSZ) systems to model Appendix G PTACs. You will need to create one PSZ system per zone which might mean 100+ systems for your 6-story apartment building. Floor multipliers are probably in order.
The PTAC fan power of 0.0003 kW/cfm includes ERVs. I’m not aware of an exception to Appendix G that would apply.
There are a few possibilities for justifying no ERV in the baseline:

-        Ventilation system runs <8000 hrs/year (hard to justify for apartments?)

-        The building is a multipurpose use and you can model additional system types in the nonresidential areas

-        6.5.6.1 exception (8.), “where the largest source of air exhausted at a single location at the building exterior is less than 75% of the design outdoor airflow rate”. This would seem to apply, since each PTAC handles the ventilation load for one zone, and the baseline would have no large common exhaust location.
Regards,
~Bill

William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer

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From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of sunayana jain via Equest-users
Sent: Thursday, March 08, 2018 11:16 AM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] exhaust heat recovery system with PTAC in eQUEST

As per ASHRAE 90.1-2013, exhaust air energy recovery is required for ventilation systems operating greater than 8000 hours per year. I am working on a baseline model of 6 storeys apartment building in climate zone 5A. As per ASHRAE 90.1-2013 Appendix G, apartments units are required to have PTAC systems with heat recovery. I am wondering, how to model PTAC with heat recovery in eQUEST. PTAC system cannot take heat recovery in eQUEST.
Also, ASHRAE does not have any information on fan power for energy recovery systems. Should the ERV fan be a part of allowable 0.0003 kW/cfm fan power?
Any suggestions will be appreciated.
Thanks,
Sunayana Jain

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