E+ PMV-PPD calculation mismatch

asked 2016-02-11 10:38:22 -0500

Peter Horvath
61 ●4

updated 2016-02-11 10:58:30 -0500

__AmirRoth__

4436 ●5 ●17 http://bleedinggreenna...

hi all!

Currently i'm investigating the PMV-PPD outputs of a DesignBuilder simulation. I exported the hourly PMV-PPD values and the ones which correstpond them (air temperature, radiant temperature, air velocity (0,137), rel.humidity, metabolic rate, clo value) When i calculate the PMV values from the 6 variables in excel i get more than 60% differnce between my calculation and the DB (e+) calculation.

Can anyone help me finding the reason of the difference? Have anyone faced this problem before?

thanks a lot, Peter

answered 2016-02-12 08:20:32 -0500

Archmage

7185 ●3 ●11

I would suggest getting a copy of ASHRAE standard 55 and comparing your spreadsheet calculations to the sample calculations in the appendix. This questioning of EnergyPlus's PMV calculations has come up many times over the years and they have been checked and rechecked again and again. Note that the averaging when using hourly values may be misleading -- it is better to use timestep frequency data.

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I've checked my spreadsheet, comparing to ASHRAE 55, it works correctly. As you written, the problem should be caused by averaging the timestep data. Unfortunately i can only access the hourly data, so if anyone tells me how to get the timestep data i will check them!