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Open Studio: Gas-Fired Burner

asked 2017-06-05 19:48:34 -0500

mcdonaa1's avatar

Open Studio: I am trying to model a gas-fired "plug-load" on the load tab to represent a kitchen burner.

When I manually size my system, my values are off by an order of magnitude, and I am uncertain as to why. I am using default schedules created by NREL, and comparing my values to CEUS and RECs. I get reasonable results when I reduce my manually sized values by an order of magnitude.

For example, when I set a gas-fired burner to 9500 BTU/h (2784 W) as a gas load, the interior gas-fired equipment yields: 169.4 MBtu But when I reduce it to 278.4 W, it yields: 16.9 MBtu

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It would be helpful if you could tell use exactly which schedule you're using and where you found it.

Julien Marrec's avatar Julien Marrec  ( 2017-06-06 03:13:27 -0500 )edit

I use a residential range schedule from a measure created by NREL where they are attempting to port BeOpt over to Open Studio. Links to the Beopt measures here: https://github.com/NREL/OpenStudio-BE...

I use one for a fuel cooking range (ResidentialApplianceCookingRangeFuel), and another for the gas-fired DHW tank (ResidentialHotWaterHeaterTankFuel).

mcdonaa1's avatar mcdonaa1  ( 2017-06-06 03:27:57 -0500 )edit

But I have this problem for commercial buildings as well using the office default schedules associated with the aforementioned...

mcdonaa1's avatar mcdonaa1  ( 2017-06-06 03:31:19 -0500 )edit

See my edit below, the schedule created here if you didn't change the measure default input amounts to 2224.331552719538 EFLH.

Julien Marrec's avatar Julien Marrec  ( 2017-06-06 03:53:18 -0500 )edit

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answered 2017-06-06 03:35:58 -0500

updated 2017-06-06 03:55:12 -0500

It would be helpful if you could tell use exactly which schedule you're using and where you found it. Also, where did you assign the OS:GasEquipment you created?


For now, I'm just going to tell you how things are calculated and how you should input your values. I'm assuming you're using the QuickServiceRestaurant template, which has a couple of gas equipment, and that you're specifically using the 90.1-2010 - QckSrvRest - Kitchen Gas Equipmentone, though it completely doesn't matter, since they all use the same schedule(cf proof [1]). I use scripting here (see proof too) to compute the equivalent annual full load hours, but since it has the same schedule for all days you could have done it manually, and noticed that the sum of daily fraction is 2.86, which is indeed equal to 2.86 * 365 = 1043.90 EFLH.

Knowing that, if you define a GasEquipment with this schedule, and a value of 9500 BTU/h // 2784 W, the total gas consumption for this one equipment is 9500 * 1043.90 / 1.0e6= 9.91705 MBTU/yr, or OpenStudio::convert(9500,"Btu/hr", "W").get * 1043.90 / 1e3 = 2904.33 kWh/yr.

Also note that you need to be careful about how you assign this GasEquipment. If you were to assign it to a space type that had 17 individual space types, you would yield about 169 MBtu/yr. Same if you assign it to a space where the linked zone had a multiplier of 17...


[1] Get Annual Equivalent Full Load Hours (EFLH) for all kitchen gas schedules in the QuickServiceRestaurant.osmtemplate. I'm using a function helper - osload - to load the model. And I'm using openstudio-standards because it has the annual_equivalent_full_load_hrs that's very handy for this.

In [1]:
require 'openstudio'
require 'openstudio-standards'
lib = osload('/Applications/OpenStudio-2.1.1/OpenStudioApp.app/Contents/Resources/QuickServiceRestaurant.osm')

lib.getGasEquipments.each do |eq|
  sch = eq.schedule.get.to_ScheduleRuleset.get
  eflh = sch.annual_equivalent_full_load_hrs
  puts "#{eq.name.to_s} - #{eflh.round(2)} EFLH"
end

Out[1]:
DOE Ref 1980-2004 - QckSrvRest - Kitchen Gas Equipment - 1043.9 EFLH
90.1-2007 - QckSrvRest - Kitchen Gas Equipment - 1043.9 EFLH
90.1-2010 - QckSrvRest - Kitchen Gas Equipment - 1043.9 EFLH
189.1-2009 - QckSrvRest - Kitchen - CZ1-3 Gas Equipment - 1043.9 EFLH
DOE Ref 2004 - QckSrvRest - Kitchen Gas Equipment - 1043.9 EFLH
189.1-2009 - QckSrvRest - Kitchen - CZ4-8 Gas Equipment - 1043.9 EFLH
DOE Ref Pre-1980 - QckSrvRest - Kitchen Gas Equipment - 1043.9 EFLH

EDIT: now that I know you're using the BEOpt measure, the schedule created with the default input of the measure amounts to 2224 EFLH. The above holds true.

I assume ResidentialApplianceCookingRangeFuel, I can recreate the schedule:

In [1]:
require '/path_to/OpenStudio-BEopt/resources/constants.rb'
require '/path_to/OpenStudio-BEopt/resources/schedules.rb'

weekday_sch = "0.007, 0.007, 0.004, 0.004, 0.007, 0.011, 0.025, 0.042, 0.046, 0.048, 0.042, 0.050, 0.057, 0.046, 0.057, 0.044, 0.092, 0.150, 0 ...
(more)
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Asked: 2017-06-05 19:48:34 -0500

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Last updated: Jun 06 '17