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# How do I view the total heat transfer coefficient through surfaces in OpenStudio/EnergyPlus?

I would like to find out what the heat transfer coefficient for my floor is in my OpenStudio/EnergyPlus model in W/m2K. I have been advised to look at the EnergyPlus timeseries outputs related to surface heat gain. I have had a look at these and cannot seem to find one that relates to total heat flow - it seems that heat transfer is split into conduction, radiation, and convection. E.g "Surface Outside Face Conduction Heat Transfer Rate per Area [W/m2]".

Is there any way of finding out what the total heat transfer rate is in terms of W/m2K of a surface (especially the ground floor)?

Additionally to this, when trying to use the 'Add Output Variable' measure that is available on BCL, the measure seems to run successfully, stating that an output variable has been added to the simulation, however I cannot seem to find this in the output files? I was under the impression I would be able to see this in the .sql file but it does not seem to be there. Any help would be very appreciated! :)

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The Envelope and Internal Load Breakdown Measure gives annual and monthly kBtu per surface type and surface, as well as non envelope gains/losses. So while it isn't normalized per area it could be modified or extended to do that.

As for why you are not seeing data in your SQL file for the outputs you added. Are there any warnings in your eplusout.err file about the variable requests?

For reference, here is what is called for this measure.

# monthly heat gain outputs
result << OpenStudio::IdfObject.load('Output:Variable,,Electric Equipment Total Heating Energy,monthly;').get
result << OpenStudio::IdfObject.load('Output:Variable,,Gas Equipment Total Heating Energy,monthly;').get
result << OpenStudio::IdfObject.load('Output:Variable,,Zone Lights Total Heating Energy,monthly;').get
result << OpenStudio::IdfObject.load('Output:Variable,,Zone People Sensible Heating Energy,monthly;').get
result << OpenStudio::IdfObject.load('Output:Variable,,Zone Infiltration Sensible Heat Gain Energy,monthly;').get
result << OpenStudio::IdfObject.load('Output:Variable,,Surface Window Heat Gain Energy,monthly;').get

# monthly heat loss outputs
result << OpenStudio::IdfObject.load('Output:Variable,,Zone Infiltration Sensible Heat Loss Energy,monthly;').get
result << OpenStudio::IdfObject.load('Output:Variable,,Surface Window Heat Loss Energy,monthly;').get

# hourly outputs (will bin by hour to heat loss or gain and roll up to monthly, may break out by surface type)
result << OpenStudio::IdfObject.load('Output:Variable,,Surface Average Face Conduction Heat Transfer Energy,hourly;').get

more

Thanks very much! That would be very useful! I downloaded the measure, however it seems to make my model crash for some reason.

The error starts: [16:26:33.662474 ERROR] Found error in state 'preprocess' with message [":/ruby/2.5.0/gems/openstudio-workflow-2.0.0/lib/openstudio/workflow/util/measure.rb failed with message cannot load such file -- C:/Users/Spare/AppData/Local/Temp/osmodel-1607094816-0/resources/measures/Envelope and Internal Load Breakdown/resources/os_lib_reporting_envelope_and_internal_loads_breakdown in eval:129:in require'\neval:129:inrequire'\n:/ruby/2.5.0/rubygems/c

( 2020-12-04 10:31:04 -0600 )edit