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
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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
F 913.564.6380

15200 Santa Fe Trail Drive
Suite 204
Lenexa, KS 66219
United States

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