Very Long Energy Plus simulation time on basic mass


I am experiencing very long ENERGY PLUS annual analysis times for basic EUI. My mass is approximately 422 in length by 200 ft width. It takes 5 minutes to just calculate one zone with no windows. I tried adding windows and after 30 minutes it still had not completed. There is 127 surfaces on this mass. (with 4 surfaces it calculates immediately).

I have other zones I need to add which would be over 800 surfaces. Sefaira takes about 8 minutes to do everything, but I want to move away from it. I feel like there should be a solution for this as it is not very useful for parametric design if the simulation takes so long.

Thank you.

Your Rhino model is in feet right? Try converting your Rhino units, and model to meters.

See here for more info: Exporting to Openstudio taking Long time


Thank you. Along with simplifying the geometry switching to meters fixed it.

Thanks for answering this one @SaeranVasanthakumar . I just wanted to say that, the reason why this happens is because E+ runs in meters under the hood and so the Honeybee components have to do a scaling operation whenever you are not working in meters. For small shoebox studies, this scaling operation doesn’t take much time but, when you have a large multizone model or a model with curved geometry, the scaling operation can take a long time.

Thank you Chris.This makes sense.

Hi Chris,

I am having a similar issue at the moment however my units are in metres. Perhaps my space is too large. It is representing a shopping centre maybe 200m long, 20m wide and 6 storeys. It has been 1 hour and is still performing zone sizing simulation.

Is exporttoopenstudio slower than exporttoenergyplus?


Hi Oscar,

I have realized that setting the Solar Distribution on the EnergySimPar component greatly increases speed. The results still seem to be indicative of a design suitable for Architectural Design. Of course, if you are going for beam reflections you will need to set it to 4.

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