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How to add exterior equipment (base utilities) in OpenStudio?

asked 2015-10-22 10:12:21 -0500

updated 2021-05-07 09:45:33 -0500

Is there a quick way to add pump power to the model as exterior equipment end use or as a base utility? I would like to add a couple pumps to an OpenStudio 1.9 model to include their energy usage as a base utility (ie, not applied to any space or zone). These pumps are not part of a hot water loop, service hot water, or an HVAC system, but are used for a greywater/rainwater collection system to pump stored rainwater into the building for toilet/urinals. I do not want to model the greywater system, but instead just want to account for the pump energy at the building level. I tried doing this on the "Facility" side tab under the "Exterior Equipment" tab, but that seems to only be for exterior lighting according to the GUI labels and when I ran the model , the pump power was assigned to exterior lighting end usage.

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answered 2015-10-22 10:56:24 -0500

Currently we support Exterior Lights but not other Exterior equipment. There are a few options for now.

  1. First is just to model as lights, which you did, but that will report as exterior lighting as you found out
  2. You could make a dummy zone that isn't included in the building area and sits somewhere away from your main building, and add there as an internal load.
  3. The third option is to add an EnergyPlus measure to your workflow to add an Exterior:FuelEquipment object to your model.
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Thanks @David Goldwasser. All the options you mentioned work. There is also another option that I believe works for my purposes (LEED). I entered the pumps under "Loads" and "Electric Equipment Definitions", entered the design level wattage for the pump I would like included in my end usage, and put the fraction lost value to 1.0. This way the pump does not create an internal load but acts as if it is ventilated to the atmosphere, while still adding the energy use to the total building energy cost. I then assigned the equipment definition to an existing utility room with a schedule.

kramerica's avatar kramerica  ( 2015-10-22 12:33:16 -0500 )edit

Cool, I think that approach is used often for traction elevators when the equipment is on the roof.

David Goldwasser's avatar David Goldwasser  ( 2015-10-22 13:12:58 -0500 )edit

answered 2016-04-21 13:55:40 -0500

In my opinion, the best approach is to use an electric equipment object, assign it to an arbitrary space/zone, and set the Fraction Radiant and Fraction Latent to 0 and the Fraction Lost to 1. This will result in no internal gains to the space/zone but the electricity consumption is correctly accounted for.

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Asked: 2015-10-22 10:12:21 -0500

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Last updated: Apr 21 '16