[Greenbuilding] HVAC COPs

[Nick Pine]

Don Eyermann writes:

> Our information, including mathematical formulae and computations are 
> available at our web sites.

Here?

http://www.isomax-terrasol.eu/en/technologie/technical-data.html

Got anything in English?

Here's a McMansion Energy Solar House (MESH) calc:

10 PI=4*ATN(1)
20 WH=80:LH=100'house dimensions (ft)
30 RC=40'ceiling R-value (ft^2-F-H/Btu)
40 GH=WH*LH/RC'ceiling conductance (Btu/h-F)
50 WA=300'window area (ft^2)
60 UW=.25'window U-value (Btu/h-F-ft^2)
70 GH=GH+WA*UW'add window conductance
80 RW=30'wall R-value
90 GH=GH+(2*(WH+LH)*8-WA)/RW'add wall conductance
100 'GH=300'total house conductance (Btu/h-F)
110 PRINT"1000'Total house conductance (Btu/h-F):";GH
120 TA=24.4'average outdoor temp (F)
130 TH=32.9'average daily high (F)
140 TD=TA-(TH-TA)'dawn temp (F)
150 HD=(70-TD)*GH'dawn heat required at 70 F (Btu/h)
160 GRAD=1000'radiator conductance (Btu/h-F)
170 TM=70+HD/GRAD'min usable store temp (F)
180 TS=140'average-day store temp (F)
190 PRINT"1010'Min/max cloudy store temp (F):";TM;TS
200 EUSE=600'indoor electrical use (kWh/mo)
210 HE=3412*EUSE/30'electric heat (Btu/day)
220 H1=24*(65-TA)*GH-HE'heat required for 1 cloudy day (Btu/day)
230 ND=5'number of cloudy days stored
240 PRINT"1020'Number of cloudy days stored:";ND
250 PRINT"1030'Approximate solar fraction:";1-2^(-ND)
260 HN=ND*H1'heat required for ND cloudy days (Btu)
270 VS=HN/(TS-TM)/62.33'cloudy store volume (ft^3)
280 HS=4'cloudy store height (ft)
290 DS=2*SQR(VS/PI/HS)'cloudy store diameter (ft)
300 PRINT"1040'Cloudy store dimensions (ft):";DS;"diam x";HS;"high"
310 AS=2*PI*(DS/2)^2+PI*HS*DS'cloudy store surface (ft^2)
320 RS=36'cloudy store R-value (ft^2-F-h/Btu)
330 GS=AS/RS'cloudy store thermal conductance (Btu/h-F)
340 ES=24*(TS-65)*GS'average day store loss (Btu/day)
350 DUSE=50'DHW use (gal/day)
360 ED=8.33*DUSE*(110-50)'DHW energy (Btu/day)
370 ESTORE=ES+ED'average store collection (Btu/day)
380 SSUN=990'sun on south wall (Btu/ft^2-day)
390 SWA=108'south window area (ft^2)
400 SWG=.5*SWA*SSUN'average south window gain (Btu/day)
410 EDAY=H1-SWG-ES'average sunspace air heating (Btu/day)
420 PRINT"1050'Estore, Eday (Btu/day):";ESTORE;EDAY
430 NHEAT=(24-DAYL)*EDAY/24'overnight heat (Btu/day)
440 NDIFF=10'day-night temp diff (F)
450 CHOUSE=NHEAT/NDIFF'overnight house capacitance (Btu/F)
460 PRINT"1060'Overnight house capacitance (Btu/F):";CHOUSE
470 DAYL=6'solar collection day length (hours)
480 TDAY=(TA+TH)/2'approximate daytime temp (F)
490 TSS=TDAY+2*.8*SSUN/DAYL'Thevenin sunspace temp (F)
500 RSS=DAYL/(EDAY/(TSS-65)+ESTORE/(TSS-TS))'Thev SS resistance 
(F-h/Btu)
510 TSC=RSS*ESTORE/(TSS-TS)'store collection time (hours)
520 TDC=DAYL-TSC'sunspace air heating time (hours)
530 PRINT"1070'Tstore, Tday (hours):";TSC;TDC
540 PP=60'pump power (watts)
550 FP=20'fan power (watts)
560 CE=PP*TSC+FP*DAYL'collection energy (wH)
570 PRINT"1080'Collection energy (Wh):";CE
580 COP=(ESTORE+EDAY)/(3.412*CE)'Coefficient Of Performance
590 PRINT"1090'Coefficient Of Performance (COP):";COP
600 TCOP=(ESTORE+EDAY)/(3.412*(PP+FP)*TSC)'with thermosyphoning mode
610 PRINT"1100'COP with thermosyphoning mode:";TCOP
620 AG=2/(RSS-1/GRAD)'min sunspace glazing area (ft^2)
630 HG=8'sunspace glazing height (ft)
640 LG=AG/HG'sunspace glazing length (ft)
650 LGR=4*INT(LG/4+1)'round up length to 4'
660 PRINT"1110'SS glazing dimensions (ft):";HG;"high x";LGR;"long"

Total house conductance (Btu/h-F): 361
Min/max cloudy store temp (F): 89.53011  140
Number of cloudy days stored: 5
Approximate solar fraction: .96875
Cloudy store dimensions (ft): 11.97667 diam x 4 high
Estore, Eday (Btu/day): 43780.96  211267.4
Overnight house capacitance (Btu/F): 21126.74
Tstore, Tday (hours): 1.41651  4.58349
Collection energy (Wh): 204.9906
Coefficient Of Performance (COP): 364.6528
COP with thermosyphoning mode: 659.6352
SS glazing dimensions (ft): 8 high x 64 long

Nick