[Equest-users] Heat Recovery Control

Mon Mar 14 11:52:43 PDT 2016

I did exactly this for a recent job for the same reasons (lockouts between setpoints for heat recovery operation).  

The only extra caution is – this is actually very easy to do, but be mindful you’ll end up adding approximately 400 components to your model after import (between the day/week/annual schedules).  If your model is already in or certain to reach “overweight” territory in terms of loading/simulation times, it may be advisable to push this towards the end of your to-do list for model development (if feasible).

If you want to more quickly/lightly approximate the savings for all seasons, you could run an hourly of your exhaust air temps at the heat recovery to come up with an annual median, then consider that exhaust temperature in relation to your 55/72 “lockout targets” to come up with an “averaged absolute annual differential” to use in combination with ERV-RECOVER-MODE = OA-HEAT/COOL.  This will deliberately overstate cooling recovery + understate heating recovery operation (or vice versa), but would hopefully ballpark what’s happening on an annual savings basis well enough.  

You could also “tune” the “light” approach to adjust the delta input in combination with a model fork using the “imported spoon-fed operation” approach (you may want to develop that schedule anyway for eventual import/use, so it wouldn’t be wasted time), but again I’d probably be inclined to ultimately land on that more “locked in” solution and just plan my model development around doing that last or towards the end.

~Nick

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Nick Caton, P.E.

  Senior Energy Engineer
  Energy and Sustainability Services
  North America Operations
  Schneider Electric

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From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Lapierre, Patrick
Sent: Monday, March 14, 2016 12:06 PM
To: Aaron Powers; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Heat Recovery Control

One way to do it would be to build a custom 8760h schedule using the schedule excel tool produced by EMIT (attached).

You output the outside temp of your meteo file and manually set them to On/Off according to the outside temps you mentionned below (0 between 55 and 72, 1 otherwise).

Then you import the schedule in your model and set your ERV to run according to this schedule.

It’s a little longer but it will do exactly what you want to.

  <http://www.bpa.ca/> 

Patrick Lapierre_ing.

plapierre at bpa.ca

De : Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] De la part de Aaron Powers
Envoyé : 14 mars 2016 12:56
À : equest-users at lists.onebuilding.org
Objet : [Equest-users] Heat Recovery Control

I'm trying to model a heat recovery device on a 100% OA VAV unit.  The supply air temperature setpoint is a constant 55 F throughout the year.  To maximize the savings, we will be locking out the heat recovery when the outside air is between 55 and 72 F.  When the outside drybulb is less than 55, we will have pre/re-heat savings, and when the outside drybulb is greater than 72 we will have sensible cooling savings.  The closest control scheme that I can find to this in eQuest is to set ERV-RUN-CTRL = "OA Exhaust DT", set ERV-RECOVER-MODE = "OA Cooling" and OA-EXHAUST-DT = 0.  But unfortunately, this will not pick up the heating savings.  

Does anyone know of a better way to model this control?

Aaron

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