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 "HgWe need a little computer to do this automatically, eg a Smart Vent!
Nick