Ventilate when the outdoor vapor pressure P(Ta,RHa) is less than the indoor vapor pressure P(Ti,RHi) in the table below, and try to do this with warmer outdoor air when the house needs heat and cooler outdoor air when it needs coolth.
20 FOR R=0 TO 5
30 PRINT TAB(6+10*R);50+5*R;
40 NEXT
50 PRINT TAB(66);80
60 PRINT
70 FOR TA=50 TO 80 STEP 2'temperature (F)
80 PRINT TA;
90 FOR R=0 TO 5
100 RHA=50+5*R'RH (%)
110 PA=RHA/100*EXP(17.863-9621/(460+TA))'vapor pressure ("Hg)
120 PRINT TAB(5+10*R);PA;
130 NEXT
140 RHA=85
150 PA=RHA/100*EXP(17.863-9621/(460+TA))
160 PRINT TAB(5+10*6);PA
170 NEXT
50% 55 60 65 70 75 80%
50F .1836264 .201989 .2203516 .2387143 .2570769 .2754395 .3121648
52 .1976689 .2174358 .2372027 .2569696 .2767365 .2965033 .3360371
54 .2126632 .2339295 .2551959 .2764622 .2977285 .3189948 .3615275
56 .2286653 .2515319 .2743984 .2972649 .3201315 .342998 .3887311
58 .2457342 .2703076 .2948811 .3194544 .3440279 .3686013 .4177481
60 .2639307 .2903237 .3167168 .3431098 .3695029 .395896 .4486822
62 .2833194 .3116514 .3399833 .3683152 .3966472 .4249791 ..481643
64 .3039678 .3343646 .3647614 .3951581 .4255549 .4559517 .5167452
66 .3259469 .3585417 .3911363 .423731 .4563257 .4889204 .5541098
68 .3493307 .3842637 .4191968 .4541299 .4890629 .523996 .5938621
70 .3741957 .4116153 .4490348 .4864544 .523874 .5612935 .6361327
72 .4006234 .4406858 .4807481 .5208105 .5608728 .6009351 .6810598
74 .4286993 .4715692 .5144391 .5573091 .600179 .6430489 .7287888
76 .45851 .504361 .550212 .596063 .641914 .687765 .779467
78 .4901487 .5391635 .5881784 .6371932 .6862081 .735223 .8332528
80F .5237118 .576083 .6284541 .6808253 .7331965 .7855676 .89031 "Hg
We need a little computer to do this automatically, eg a Smart Vent!
Nick