[Bldg-sim] ASHRAE 55/ISO 7730 Comfort calculation

[Macdonald, Iain]

Dear All,
 
I've recently coded the equations in ASHRAE 55 (2004) for calculating PMV and PPD and cross referenced these to ISO 7730:2005 (the reference ASHRAE gives).  There are several differences:
1) line 250 - ASHRAE has an extra factor of 6.45 in the equation
2) line 300 - ISO has (TRA/100)*4, ASHRAE (TRA/100)**4
3) line 480 - ISO has (TRA/100**4), ASHRAE has (TRA/100)**4
4) line 520 - ISO does not define a value for HL6 (ASHRAE has this on line 490)
 
I believe that difference (1) is unimportant as its setting the initial guess for an iterative loop.  However, for the other three differences I believe that ASHRAE is correct and ISO has typos.
 
I also have differences in the output from the example cases.  The differences are:
1) ASHRAE cases 3 and 6 give 11% PPD (the standard has 10%)
2) ISO case 7 gives 8% PPD (the standard has 10%)
 
The ASHRAE cases do not concern me too much as the PMV is the same to one decimal place, but the PMV in the ISO standard is quite different (0.50 in the std, 0.36 by my calculations).
 
Does anyone:
1) disagree with my conclusions as to the differences in the printed code (i.e. you do not think ISO has typos)?
2) have any insights as to the numerical differences (I think that there may be a typo in the ISO standard)?
 
Thanks,
 
Iain
 
Dr. Iain Macdonald, Ph.D.
Research Officer / Agent de recherches
Indoor Environment Research program / Programme de recherche sur l'environnement intérieur
Institute for Research in Construction / Institut de recherche en construction
National Research Council Canada / Conseil national de recherches Canada
1200 Montréal Road / 1200 chemin Montréal
Ottawa Ontario K1A 0R6
Phone/Tél: (613) 993-9676
Fax: (613) 954-3733
Email: iain.macdonald at nrc-cnrc.gc.ca <mailto:iain.macdonald at nrc-cnrc.gc.ca> 
 
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