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# EnergyPlus Energy-Balance

Hey, is there a simple possibility to calculate (output variable) the energy balance of a building? Thank you for your help!

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What do you mean by "energy balance of a building"? There are several output variables that describe the various components of the energy balance on a zone, but I don't know what a single variable for the whole building energy balance would represent? Typically you need at least two output variables to indicate a balance, i.e., Heat in = Heat out.

( 2015-10-09 09:41:06 -0500 )edit

There is a single value metric related to energy balance called the balance point temperature (BPT). It's used with respect to heating (and only heating). BPT represents the outdoor dry bulb temperate at which the internal gains (solar, plug, etc) equal the losses through the envelope. Designs with lower BPT are better because it needs to be colder before the heater is turned on. It should be noted though, BPT is a simple metric that eliminates a lot of complexity and should be used with caution.

Is this what you're looking for?

( 2015-10-10 14:59:50 -0500 )edit

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Do you try to figure out the contribution of each components in the heating or cooling energy consumption?

If yes, you can check the "Sensible Heat Gain Summary" in the <filename>Table.html file. It looks like: Capture.PNG

You need to add one of the IDF object to your IDF file.

Output:Table:SummaryReports, AllSummary;

or

Output:Table:SummaryReports, SensibleHeatGainSummary;

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There are in fact standard outputs from EnergyPlus and EPCompare which can be seen as energy balance results. For instance look at the following HTML output: In this case you see how much energy is produced and how much is consumed, including numbers indicating the degree of energy self-sufficiency of the building. With EPCompare, the "energy balance" is displayed graphically:

Of course, these examples apply only to cases where all relevant energy is electric.

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