[Equest-users] Simulate Heat Gain from Power Distribution Equipment

Tue Oct 18 08:07:06 PDT 2016

A leading thought:  The best way to learn is by trying, but having “nailed down” mech/elec room loads & exhaust behavior a few times – I caution this may not be a relatively good use of your simulation development time, in the big picture.

In addition to Chris’s suggestion to set up a process source load, you’re left with considerations to (a) quantify the amount of losses in a realistic peak condition (considering the relative loading for your transformers) and (b) determine what that associated hourly load profile looks like over the course of a year.  You can back-of-envelope / shoot from the hip for both items (and if you’re still reading, that’s probably my suggestion in most cases), but what follows explains how you can go way further down the rabbit hole:

This would be a few steps trickier, but you can also have the simulation determine and inform you of hourly transformer losses based on relative transformer loading via the optional meter inputs for transformer capacity and for a curve to describe losses as a function of the PLR (relative to the capacity).

One or two eQUEST versions ago, I performed a study using these features to explore the relative savings for a few different premium efficiency vs. standard transformers of different capacities.  Constructed a few comparative curves by adding up the tested coil and core losses at part load & summing losses relative to the nominal capacity.

That study was performed for a series of buildings characterized by seasonal usage (like schools).  The ROI wasn’t terribly impressive.  Better relative savings appeared realizable with transformers that would be consistently loaded moderately-to-heavily (like above 50% of their rated capacity) year-round.

Limitations:

·         For the cases I’ve given this serious consideration, I determined it would be impractical to define/assign zone/system loads to one sub-meter per transformer in a power distribution system.  Doe2/eQUEST permits assignment of meters/sub-meters by SYSTEM and overridden by ZONE, but in the real world you can easily run into cases where some load enduses (like lights, plug loads) can easily split between high and step-down voltage distributions in a given ZONE.  doe2 meters/transformers are kinda hard to consider “spatially.”  With this in mind, think hard about whether you could reasonably simulate all distribute losses for the entire building at your main meter, then distribute those gains between the rooms conditioning/exhausting step downs (a conversation with your electrical designer might facilitate this thought exercise).

·         At present, meter-level loss inputs won’t allow you to directly assign those transformer losses to a  particular space (I think I proposed this some time ago as a feature request)… so you’d still need to extract the associated hourly heat gains via custom hourly report then feed them in as a process source load as Chris outlined.

~Nick
[cid:image001.png at 01D22921.9EF98D20]
Nick Caton, P.E., BEMP
  Senior Energy Engineer
  Energy and Sustainability Services
  Schneider Electric

D  913.564.6361
M  785.410.3317
E  nicholas.caton at schneider-electric.com<mailto:nicholas.caton at schneider-electric.com>
F  913.564.6380

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From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Chris Jones via Equest-users
Sent: Monday, October 17, 2016 3:51 PM
To: Darryl Kasun <darryl.kasun at gmail.com>
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Simulate Heat Gain from Power Distribution Equipment

Darryl,
You can add a process gain using SOURCE-TYPE = PROCESS and assign a SOURCE-SCHEDULE. This will add heat to the space without adding energy to the results.

Christopher Jones, P. Eng.
Rowan Williams Davies & Irwin Inc.
Consulting Engineers & Scientists
901 King Street West, Suite 400, Toronto, Ontario, M5V 3H5
T: (519) 823-1311 ext 2052
M: (416) 697-0056

From: Equest-users [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Darryl Kasun via Equest-users
Sent: Monday, October 17, 2016 4:42 PM
To: equest
Subject: [Equest-users] Simulate Heat Gain from Power Distribution Equipment

Hello eQUESTers,

I would like to simulate the heat gain from power distribution equipment (like transformers) into a space but do not want this load attached to a meter.  Reason for this is there are EFs that serve some of the rooms where power distribution equipment is located and I want to model how these EFs should operate.

The only way I can think of adding this heat gain is through the occupant heat gain inputs.

Any thoughts on this (good or bad)?

Thanks
Darryl

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