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Reuse shadow calculations for iterative / parametric building mass simulations

asked Oct 10

AadriaanW's avatar

Is there a way to seperate the shadow calculations from the E+ simulations and implement a previously calculated shadow calculation?

We are setting up our own parametric simulation tool where we will simulate thousands of iterations of a building design. Some of these will have changes that will affect the shadow calculation results (shading, glazing%, etc) and others not necessarily (insulation value, SHGC in glazing, etc). Since shadow calculations can take up quite a bit of time in some simulations and we in general want to reduce simulation time since we are doing thousends of them at the same time I was wondering if there is a way to "reuse" older shadow calculations that are applicable to a specific iteration, or if the shadow calculation is native to the E+ simulation and will always be simulated.

These simulations are for a first phase / schematic design phase, so we are not striving for high accuracy, but more a general overview of the options in variations for a building mass.

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answered Oct 10

Yes, EnergyPlus has this exact feature for the reason of speeding up simulations. In the ShadowCalculation object, there is an Output External Shading Calculation Results field that will export a CSV file. You can then import the CSV in a subsequent simulation using "Imported" in the Shading Calculation Method.

From what I can tell, there was a bug in v9.1 that got fixed in v23.1, so if you encounter a crash, update to a newer version of EnergyPlus.

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Asked: Oct 10

Seen: 68 times

Last updated: Oct 10 '24