Tony wrote:

The ASHRAE 55-2004 standard says 80 F at 55% would be comfortable.

I can tell you from experience the past two weeks, that 80 degrees F
at 55%-60% humidity feels much better than 76 degrees at 80% humidity

The ASHRAE 55-2004 standard says you would be more comfy at 76/80.

Nick

20 CLO = 1'clothing insulation (clo)
30 MET=1.1'metabolic rate (met)
40 WME=0'external work (met)
50 VEL=.1'air velocity
70 DEF FNPS(T)=EXP(16.6536-4030.183/(TA+235))'sat vapor pressure, kPa
80 DATA 80,57.5
90 DATA 78.707,80
100 FOR CASE = 1 TO 2
110 READ TA,RH
120 TA=(TA-32)/1.8
130 TR=TA
140 PA=RH*10*FNPS(TA)'water vapor pressure, Pa
150 ICL=.155*CLO'clothing resistance (m^2K/W)
160 M=MET*58.15'metabolic rate (W/m^2)
170 W=WME*58.15'external work in (W/m^2)
180 MW=M-W'internal heat production
190 IF ICL.078 THEN FCL=1+1.29*ICL ELSE FCL=1.05+.645*ICL'clothing factor
200 HCF=12.1*SQR(VEL)'forced convection conductance
210 TAA=TA+273'air temp (K)
220 TRA=TR+273'mean radiant temp (K)
230 TCLA=TAA+(35.5-TA)/(3.5*(6.45*ICL+.1))'est clothing temp
240 P1=ICL*FCL:P2=P1*3.96:P3=P1*100:P4=P1*TAA'intermed iate values
250 P5=308.7-.028*MW+P2*(TRA/100)^4
260 XN=TCLA/100
270 XF=XN
280 N=0'number of iterations
290 EPS=.00015'stop iteration when met
300 XF=(XF+XN)/2'natural convection conductance
310 HCN=2.38*ABS(100*XF-TAA)^.25
320 IF HCFHCN THEN HC=HCF ELSE HC=HCN
330 XN=(P5+P4*HC-P2*XF^4)/(100+P3*HC)
340 N=N+1
350 IF N150 GOTO 480
360 IF ABS(XN-XF)EPS GOTO 300
370 TCL=100*XN-273'clothing surface temp (C)
380 HL1=.00305*(5733-6.99*MW-PA)'heat loss diff through skin
390 IF MW58.15 THEN HL2=.42*(MW-58.15) ELSE HL2=0'heat loss by sweating
400 HL3=.000017*M*(5867-PA)'latent respiration heat loss
410 HL4=.0014*M*(34-TA)'dry respiration heat loss
420 HL5=3.96*FCL*(XN^4-(TRA/100)^4)'heat loss by radiation
430 HL6=FCL*HC*(TCL-TA)'heat loss by convection
440 TS=.303*EXP(-.036*M)+.028'thermal sensation transfer coefficient
450 PMV=TS*(MW-HL1-HL2-HL3-HL4-HL5-HL6)'predicted mean vote
460 PPD=100-95*EXP(-.03353*PMV^4-.2179*PMV^2)'predicted % dissatisfied
470 GOTO 490
480 PMV=99999!:PPD=100
490 PRINT TA,RH,PMV,PPD
500 NEXT CASE

Temp (C) RH PMV PPD

26.66667 57.5 1.106953 30.83258
24.44445 80 .6077689 12.74688
25.94833 80 1.106916 30.83087

Innova AirTech Instruments has an excellent comfort web site...
http://www.impind.de.unifi.it/Impind...va/thermal.htm