HB PMVMap air speed influence on PMV

Hi all,

I am looking at how air speed improves interior thermal comfort in hot conditions based on a complex shaped building. However, when I change the air speed input for HB PMVmap component from 0.1m/s to 1m/s, there is minimal change(nearly no change) of the result; while in LB PMV component and DesignBuilder PMV calculator, a same airspeed change does cause obvious improvement on PMV.

I also tried the same air speed change on a shoebox model to check and it turns out a considerable improvement on PMV with both ways so the problem i came with might be related to the building massing. But as I assume PMV calculated directly from a formula, it doesn’t seem to make sense that building shape affects the influence level of air speed.

And hi @chris you’ve mentioned in another topic that HB PMVmap is more precise in sumulating real conditions. I wonder how air speed is taken into account in HB PMVmap component? Does the input air speed go through simulation process or not? Or to say, is the PMV calculated from a final air speed simulated from input, rather than the input air speed itself?

Look forward to any reply.


Hi @tiantmz ,

Sorry for the late reply. Are you certain that the sensors that you have for your PMV comfort map are on the inside of the Rooms of the model? If you read the description of the air_speed input on the PMV Comfort Map component, you see that the input only applies to sensors that are on the inside of Rooms:

The EPW wind speed is always used to determine the speed on sensors that are outside of any rooms.

If you are certain that your sensors are in the inside of your Honeybee Rooms, then please upload a minimal sample file so that I can recreate the issue and take a look.

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And you can see in the description that it’s supposed to use your input air_speed directly for the PMV model for indoor sensors. This is different than how the wind speed is interpreted from the EPW, where it gets multiplied by a factor (0.66) to better approximate the conditions on the ground.

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Hi Chris,

Thank you for the explaination. I’ve solved this by simplifying the model - the original one I use is planarized from a curved shape so it has numerous faces (and maybe some intersects or bad surfaces). After simplification the HB PMVMap runs correct results.

I wonder if there are limitations for model face numbers or volume in Honeybee components?


Not really. It’s just whatever limit is dictated by the memory of your computer and how long you have to wait for the planarized result to be processed. However, depending on how you planarized it, you might have created a Room with an open volume, which could also cause this issue.

Did you validate your model with the HB Validate Model component before you tried to simulate it? The validation would tell you if the Room volume was not closed if that was the issue.