I'd appreciate some sensible guidance. Please don't dampen my spirits...
Section 6.5.6.1 describes that required energy recovery systems (ERVs) "shall have at least 50% energy recovery effectiveness", meaning "a change in enthalpy of the outdoor air supply equal to 50% of the difference between the outdoor air and return air enthalpies at design conditions".
My reaction is to model this by setting both the sensible and latent effectiveness (ERV-SENSIBLE-EFF and ERV-LATENT-EFF) to 50% (0.50).
Is this correct?
Ye be thanked,
~Bill
William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer
[cid:image007.jpg at 01D2CFD5.C3882970] [cid:image008.jpg at 01D2CFD5.C3882970]
134 South Fitzhugh Street Rochester, NY 14608
T: (585) 698-1956 F: (585) 325-6005
bbishop at pathfinder-ea.com
[http://png-5.findicons.com/files/icons/977/rrze/720/globe.png]Carbon Fee and Dividend - simple, effective, and market-based.
It is my interpretation as well and what I always do.
[Bouthillette Parizeau]
Patrick Lapierre_ing. BEMP
plapierre at bpa.ca | t: 5143833747x2807
De : Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] De la part de Bishop, Bill via Equest-users
Envoy? : 18 mai 2017 12:53
? : equest-users at lists.onebuilding.org
Objet : [Equest-users] ASHRAE 90.1 ERV 50% energy recovery effectiveness - eQUEST inputs?
I'd appreciate some sensible guidance. Please don't dampen my spirits...
Section 6.5.6.1 describes that required energy recovery systems (ERVs) "shall have at least 50% energy recovery effectiveness", meaning "a change in enthalpy of the outdoor air supply equal to 50% of the difference between the outdoor air and return air enthalpies at design conditions".
My reaction is to model this by setting both the sensible and latent effectiveness (ERV-SENSIBLE-EFF and ERV-LATENT-EFF) to 50% (0.50).
Is this correct?
Ye be thanked,
~Bill
William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer
[cid:image002.jpg at 01D2CFD6.4B8C42C0] [cid:image003.jpg at 01D2CFD6.4B8C42C0]
134 South Fitzhugh Street Rochester, NY 14608
T: (585) 698-1956 F: (585) 325-6005
bbishop at pathfinder-ea.com www.pathfinder-ea.com
[http://png-5.findicons.com/files/icons/977/rrze/720/globe.png]Carbon Fee and Dividend - simple, effective, and market-based.
I believe this would be correct in the baseline - assuming 100% OA system.
Chris Baker
CCI Alliance of Companies
Fort Wainwright, Alaska
907-356-1681 (x105) office
907-750-4922 cell
Bill,
For all practical purposes, I also simply set the sensible and latent effectivenesses to 50%. If your energy model will get thorough scrutiny, you may want to use Equation 6-K in the User's Manual, 2013 edition.
Keith Swartz, PE | Senior Energy Engineer
Seventhwave
608.210.7123 seventhwave.org
Bill,
Yes, Equation 6-J of the 2010 User's Manual (p. 6-107) is the same equation that I referenced.
I noticed that the equation does not have the correction factor for unequal airflows, which is the "monkey wrench" I had in mind to caution against. Several manufacturers include this factor in their effectiveness calculation. The graphic below is from a presentation by Trane.
[cid:image007.jpg at 01D2D2E4.B1FE86B0]
Usually the exhaust air flow is lower than the outside air flow due to building pressurization.
So when should the flow ratio be applied? Any manufacturers or 90.1 committee members want to chime in?
Keith Swartz, PE | Senior Energy Engineer
Seventhwave
608.210.7123 seventhwave.org
Yes, uneven airflows complicate things, and can be used by manufacturers to game the system. There are other considerations, such as how to treat the heat gains from fan motors. (Inefficient fans add more heat to the airstream(s), which can benefit the wintertime effectiveness but use more fan energy.) Passive House has been looking at this closely:
http://www.phius.org/NAPHC2014/Semmelhack-HRV-presentation.pdf
~Bill