# [Bldg-sim] Heat Recovery - Effectiveness Calculation

Carol Gardner gems at spiritone.com
Wed Jul 9 15:45:44 PDT 2008

```The manufacturer of the heat recovery system should be able to provide
you with this number. It varies by system type and by manufacturer so
it's best to call the rep of whatever system you are using. I imagine
they calculate the number based on average conditions and according to
an industry standard.

Carol Gardner

Mark Prince wrote:
> Good afternoon,
>
> I'm currently modeling a laboratory building HVAC system that has a sensible heat recovery system.  The heat recovery system is a water/glycol run-around loop type system.  In eQuest there is an input, under the airside system tab, that allows you to fill in the effectiveness of your heat recovery system.
>
> My question is this, how should I calculate this effectiveness?
>
> Currently, I've calculated the effectiveness based on the design documents.  According to the equipment schedules the exhaust air is at 72 F, and the outside air heat recovery coil has a scheduled performance of 6 F entering and 35.5 F leaving.  Based on these numbers I've calculated a design effectiveness of 44.6%.  Please see the below equation:
>
> 35.5 - 6     =   0.446
> 72  -   6
>
> However, a colleague of mine is wondering if this is the correct way to determine effectiveness for the eQuest program.  He is wondering if the effectiveness might be calculated based on the design air temperature (DAT) that is always leaving the air handler (55 F), or some other way.
>
> Does anyone know?
>
> Sincerely,
>
> Mark Prince
> Affiliated Engineers
> 5802 Research Park Blvd.
> (608) 441-6668
> mprince at aeieng.com
>
> _______________________________________________
> Bldg-sim mailing list
> http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
> To unsubscribe from this mailing list send  a blank message to BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG
>
>
>

```