Document 20M56eD0noDoroOanLGdn1V6

538 CHAPTER 37 1959 Guide Table 8___ Degree Days for Industrial Heating in Various Gties of the United States* Annual TM< lor a Norm! Heating Seaton Degree Days State cBy Statu SSF Rasa Bate Oegree Dayt, dry State 4SF SSF 6at Baso Degree Deft Oty 45f SSF Bate *" Ala.... Montgomery............ Aris... Ark.... Cal... Fn inn San Francisco......... San Luis Obispo... Col-... Pueblo....................... Conn.. D.G .. Fla-... AA+ulauia..................... Qwa. uManunlUaUhi _. Idaho.. T * 1 faim 329 276 519 1757 1499 1769 1041 1045 1034 2161 1969 504 229 37 1478 1188 1328 803 384 230 3433 3261 3237 2487 127 711 231 2814 4140 3743 Md.... Mass. . Mich. - A Imnd T *1 ", 1787 1514 3131 2491 3603 3419 5499 1487 1949 1990 Okla... Oklahoma City.... 600 2321 373 272 3147 3425 3757 1835 4307 1911 1868 Grand Rapids......... 2332 4177 4029 FuC at * p '.j g"`.* " "" Pa....... Harrisburg............... Philadelphia.......... Pittsburgh............... 2337 1565 1122 1938 1377 3837 3236 2695 3755 3028 Sault Ste. Marie 4049 6575 R. I... Block Island........... 871 3388 Minn.. 3309 5417 S. C... Charleston.............. 336 St. T*ul..................... 2497 5497 Greenville................ 297 1502 Miss... \r; v Mo___ Columbia.................. Kansas City............ Springfield............... Havre........................ Neb... North Platte........... Nev. .. 1252 1635 1463 1186 982 3736 2843 2874 3023 2291 2284 2833 1670 2646 468 3231 2980 2745 2423 5874 5071 5131 4152 3982 4801 3468 4640 S.D___ Huron...................... . 3743 Pierre........................ 3162 2590 Tenn. . Tex... 242 431 166 419 786 32 San Antonio............ Utah.. 1978 Salt Lake City------ 1475 5678 5234 4628 6045 1398 1741 1284 im 915 2220 919 754 43 110 484 305 3981 3202 Ind___ F JU" Airl 1* la------- 799 1397 3370 2296 2440 2335 4142 4180 N. J... N.M.. N.Y... 1926 3579 Qiui^ City................ 4732 Kan... 1652 1385 1152 2690 2962 2587 N.C.. Ky.. La.... Me... Lexington................ Louisville................. New Orleans......... Shreveport............. 17 * 1 itl73 2956 2530 2557 2294 30 565 5236 4572 N.D.. Ohio Wilmington............ Williston................ 1123 2904 Vt........ 1634 3106 Va....... Norfolk................... 2359 4316 2412 4023 Wash. 2341 4231 172 229 3831 4616 1388 W. Va. 729 Wis... 6399 Walla Walla........... Madison.................. Wyo.. 1600 3255 3014 4984 3652 7121 554 1928 260 1496 549 1895 184 408 1741 507 993 2062 2185 3672 2365 2565 1506 3327 1147 2784 3318 3034 3067 5331 4850 4817 2500 4700 3208 5450 * Fran Dye Day flgndliget-, by C. Sttock and C. H. B- HctehUa (Tbe ebtcr nouian. 1837, pp. US-1M). Value* are not coortinated with Table 1 whjch is been Estimating Fuel Consumption for Space Heating 539 erage indoor temperature of approximately 70 F is assumed throughout the period. If an average indoor temperature other than approximately 70 F is to be used, the number of degree days should be obtained for the new base. Example 7: An eight-story building in Pittsburgh is operated with a daytime temperature of 70 F. The calculated heat loss is 10,500 Btu per (hr) (degree temperature difference). What is the estimated average yearly steam consumption for building heating? Solution: Since the average indoor temperature is approxi mately 70 F, the degree days from Table 2, based on 70 F may be used. Therefore, from Table 2, Pittsburgh has 5048 degree days per normal season. Inserting in Equation 5: 10,500 X 24 X 5048 1000 1,272,000 lb of steam. Consideration has been given to the difference in steam utilization of different types of buildings, and Table 7 shows actual average units for these various types. These figures were obtained from operating results in 896 buildings located in all sections of the United States. Being averages, and for small groups in each type, the figures may need considerable modification to allow for local variations. It should be especially noted that the steam used for hunting water for service is not included in the values given in Table 7. Additional figures are to be found in a paper presented before the Society" Example 8: A store in Philadelphia with a heating system designed to maintain 70 F indoors in 0 F weather 250,000 cu ft of bested space. What would be the estimated average yearly steam consumption of purchased steam for heating? Solution: According to Table 7, a store would use 0.624 lb of steam per degree day per 1000 cu ft heated space. From Table 2, Philadelphia has 4523 degree days per normal year. Inserting in Equation 4: F = 0.624 X 250 X 4523 - 706,000 lb of steam. Degree Day as an Operating Unit The degree day is also widely used as a means of com paring the efficiency of the fuel consumption of one period with another for the same building. Since the fuel consump tion is approximately proportional to the weather (degree days), and since the periods to be compared may not have the same weather conditions, the comparison can be made only after the fuel consumptions have been computed on a comparable weather basis, that is, upon the actual number of degree days occurring for a given month and year in the . city under consideration. Since fuel consumption is propor tional to the number of degree' days, plant operators fre quently compute each month the fuel burned per degree day by the heating plant. The resulting unit value, by riWmnAiing the outdoor temperature variable, indicates whether the operating efficiency of the plant is above or below the pre vious month or year. INDUSTRIAL DEGREE DAYS When estimating the heating requirements of warehouses, factories, and other buildings where the indoor temperature to be maintained differs greatly from the usual indoor tem perature range of 68 to 72 F, it is common to use degree days based on temperatures of 55 to 45 F. These are gen erally referred to as industrial degree days, and are listed in Table 8 for a number of cities using both 55 F and 45 F as the base. In general, the degree days (55 F base) are used when the temperature of the heated space is to be main tained at approximately 60 F. For an inside temperature of about 50 F, the degree days calculated on a 45 F base should be used. The industrial degree days are useful for estimating fuel consumption by comparison between localities in which the difference in degree days is not too great, and where the known fuel consumption of one building may be used to determine unit consumption per degree day. MAXIMUM DEMANDS AND LOAD FACTORS In one form of district heating rates, a portion of the charge is based upon the maximum demand of the building. The maximum demand may be measured in several dif ferent ways. It may be taken as the instantaneous peak or as the rate of use during any specified interval. One method is to take the average of the three highest hours during the winter. These figures ar shown for a number of buildings in Detroit in Table 9." Table 9 .... Building Load Factors and Demands of Some Detroit Buildings Budding ClatdficaHoa load Factor lb of Demand per (Hour) (SgFtFOK) Clubs and Lodges....... ................ Hotels................................................ Printing............................................ Offices................................................ Apartments.................................... Retail Stores................................... Auto Sales and Service............... Banks........................................... Churches........................................... Department Stores....................... Theaters........................................... 0.318 0.316 0.287 0.263 0.255 0.238 0.223 0.203 0.158 0.138 0.128 0.184 0.207 0.217 0.209 0.225 0.182 0.248 0.158 0.152 0.145 0.151 These maximum demands were measured by an attach ment on the condensate meter, and therefore represent the amounts of condensate passed through the meter in the highest hours, rather than the true rate at which steam is supplied. There might be slight differences in -these two quantities due to time lag and to storage of condensate in the system, but wherever this has been investigated it has been found to be negligible. The load factor of a building is the ratio of the average load to the load and is an index of the utilization. Thus, in Table 9, the theaters, operating for short hours, have a load factor of 0.126 as compared with the figure of 0.318 for clubs and lodges. REFERENCES 1W. S. Harris and R. J. Martin: Heat transmitted to the I=B=R research home from the chimney (ASHVE Transac tions, Vol. 59, 1953, p. 97). * S. Konxo: The Stoker-fired Warm-air Furnace in the Re search Residence (University of Illinois, Engineering Experi ment Station Circular 39, 1939, p. 98). ' Performance of a Hot Water Heating System in the J=B=R Research Home at the University of Illinois (University of Illinois, Engineering Experiment Station Bulletin No. 349, January 4, 1944). 4 W. G. Colborne: Performance of intermittently-fired oil furnaces (ASHAE Transactions, Vol. 63, 1957, p. 427).