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Surface Window Net Heat Transfer Rate

asked 2017-06-04 05:03:10 -0600

gonchotorena gravatar image

updated 2017-08-06 07:23:00 -0600

In Openstudio, i´m trying to get the heat balance of surfaces and windows (The equivalence of heat balance of DesignBuilder), I know that for surfaces I have to use "Surface Average Face Conduction Heat Transfer Rate", but I wondered If its correct using "Surface Window Net Heat Transfer Rate" for the heat balance on windows, because in the pdf of InputOutput reference does´t appear this value, the search tool doesn´t find it.

So, what´s exactly the definition of "Surface Window Net Heat Transfer Rate"?

thanks you for your attention and best regards,

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answered 2017-06-05 10:54:49 -0600

There is a section in the InputOutput Reference that lists the output variables EnergyPlus will generated for window surfaces.

  • For all windows in a zone, use Zone Windows Total Heat Gain Rate AND Zone Windows Total Heat Loss Rate to calculate net heat transfer rate
  • For one specific window surface, use Surface Window Net Heat Transfer Rate

In OpenStudio, the Zone Windows output variables can be added to ResultsViewer by toggling them "ON" in the Output Variables tab on the left of the application window (see below).

image description

Adding Zone Windows output variables to ResultsViewer

In OpenStudio, the Surface Window output variable CAN NOT be added to ResultsViewer in the same way. Instead, you will need to use a measure called AddOutputVariable that you can download for free from the Building Component Library. After downloading, you should be able to:s

  • click on the Measure tab on the left of the application window
  • expand the Reporting / QAQC category and see the AddOutputVariable measure
  • drag and drop it from the right side into the OpenStudio Measures category
  • enter the inputs for the new output variable on the right (see below)

image description

Using the AddOutputVariable measure

After running a simulation, you should then be able to view this output variable in ResultsViewer.

NOTE If you leave the Key Name input field set to "*", then EnergyPlus will report the net heat transfer rate for ALL windows in the model. If you only want the output variable for a specific window surface, enter the name of that surface object on this line instead.

You can read more from a related question here.

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Asked: 2017-06-04 05:03:10 -0600

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Last updated: Jun 05