Re: [EnergyPlus_Support] Fanger PMV miscalculation

[Linda Lawrie <linda@xxxxxxxxxx>]

As noted in the "Issues Addressed" file that comes with the V1.2.2 
installation:

Folder: EnergyPlus
CR Number: 5641
Type: Defect
Addressed In: 05.03.16 V1.2.2.023
Synopsis for Users: Fanger thermal comfort model PMV results low by 
about 0.5 to 0.7 units on ASHRAE sensation scale.

Details from our configuration management software:

 From user e-mail on 20Feb2003:
I found there is a pretty constant difference between Fanger's PMV
calculated by E+ and PMV calculated by ASHRAE's software COMFORT(RP-
781). I let E+ output air temp, MRT and humidity and obtained air
velocity, human clothing and activity level from IDF file and put
these numbers into COMFORT, the comfort index values such as PMV and
TSENS are different significantly.  For PMV, E+ is always half scale
higher.

Can somebody check this problem?

 From user e-mail on 27Feb2003
Attached are a simple IDF file and the inputs and
outputs from COMFORT. I just selected several sets of
data to test, covering the comfort range.

A copy of the COMFORT program can be purchased from
ASHRAE or you can contact xyzxyz to ask for a copy.

I think since the difference is not neglectable,
either of the programs must have problems. Hope we can
find it soon.

MJW 04Mar2003
I cannot reproduce the eplus results listed in the user's 
spreadsheet.  Have asked for more details.

 From user e-mail 05Mar2003
Thank you for your instruction. I think the problem is
E+ PMV calculate work efficiency into metabolic rate
but COMFORT deos not, i.e., it assumes all the
metabolic rate goes to internal heat. Therefore, I
changed the IDF file and made the activity level to be
exactly 1 met and work efficiency 0. Then the
comparison shows PMV agrees well if cool. I am very
glad at this result. But there is still 0.3 difference
if warm. And Pierce TSENS and DISC are not very close.
Especially DISC should be higher than TSENS when warm,
but my results are just the opposite. Could you please
check my inputs to see whether they are right?

By the way, I am using E+ v1.0.1 and the weather data
is San Francisco TMY2 weather but not Chicago. If you
change to SF weather you will get the same results.

MJW 05Mar2003
Even though the user is running v1.0.1, there have been no changes to 
the thermal comfort module since then except for a change in the 
copyright notice.

Input/Output -->  test files\defect files\5641-*
Weather --> USA_CA_San.Francisco_TMY2.epw

MJW 08 Oct 2004
This is on the punchlist, unfunded, marking this CR verified deferred.

BG Mar-11-2005
In looking at Fanger PMV results from lots of building models, I am 
seeing trends that go in the wrong direction.  I suspect that E+ has 
a serious error in Fanger PMV calc.  For example, PMV goes up when it 
seems like it should go down.  Spent some time comparing E+ code to 
CH8 equations (in ASHRAE HOF)  but didn't find any obvious errors, 
except maybe where the E+ code is dividing absolute temperatures by 
100 for some reason.  I disagree that this CR can be closed (although 
it may need explicit funding to deal with).  Added a report variable 
for clothing surface temperature and will test to see if produces 
reasonable numbers

BG Mar-14-2005
After reporting more variables, the trends do seem to go in the right 
direction.  But the results do seem low.  Identified error in Latent 
heat from respiration and changed code.  equation now matches ASHRAE 
Handbook of Fundementals and Peirce model in EnergyPlus.  Raises 
results for PMV by about 0.5 to 0.7 units on ASHRAE sensation scale.

BG Mar-15-2005
Although I am confident that the fix checked-in on 3/14/2005 improves 
E+'s prediction for Fanger PMV, this CR involves comparing to the 
ASHRAE Comfort tool, and this has not been done.  So it may still 
require a lot of effort to do a good job of  "verifying."    I 
couldn't access the original D. Maloney Msc. thesis documentation to 
verify how the error may have crept in by converting units or 
something.     I did compare results to the E+ implementation of 
Pierce model and they now agree much better in most situations (I can 
provide plots of this if desired).


Linda

EnergyPlus WebSite: http://www.energyplus.gov
Owner: EnergyPlus_Support list
Member: EnergyPlus Development Team



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