Document J3DKZbGENgRVMMrjDX0568Q22

450 CHAPTER 18 1956 Guide deg. below 65 F. For any one day, when the mean temperature is less than 65 F, there are as many degree-days as there are degrees difference in temperature between the mean temperature for the day and 65 F. De gree-days may be calculated on other than the 65 F base for use mainly for warehouse and other industrial spaces in which temperatures to be maintained are considerably below the 68 to 72 F range. They are listed in a later section of this chapter. Studies made by the National District Heating Association11 of the metered steam consumption of 163 buildings located in 22 different cities and served with steam from a district heating company, substantiate the approximate correctness of the 65 F base chosen by the gas industry. . Table 2 lists the average number of degree-days which have occurred over a long period of years, by months, and the yearly totals for various cities in the United States and Canada. The number of degree-days for United States cities were calculated by taking the difference between 65 F and the daily mean temperature computed as half the total of the daily ipaximum and the daily minimum temperatures. The monthly averages were obtained by adding daily degree-days for each month each year and dividing by the number of days in the month; then totaling the respective calendar monthly averages for the number of years indicated and dividing by the number of years. The total or long term yearly average degree-day value is the summation of the 12 monthly averages. Degree days for Canadian cities were supplied by the Canadian Meteorological Division of the Department of Transport, and were computed from the mean tem perature normals on record for the various stations. (See Note c, Table 2.) Any attempt to apply the degree-day method of estimating fuel con sumption for less than one month would be of very little value. It should be noted that this method of calculation is based on a long term average and cannot be expected to coincide with any single year in calculating fuel requirement. Individual yearly degree-day calculations may vary as much as 20 percent above and below the long term average. If the degree-days occurring each day are totaled for a reasonably long period, the fuel consumption during that period as compared with another period will be in direct proportion to the number of degree-days in the two periods. Consequently, for a given installation, the fuel consumption can be calculated in terms of fuel used per degree-day for any sufficiently long period, and compared with similar ratios for other periods to determine the relative operating efficiencies with the outside temperature variable eliminated. Computation and Application The general equation for calculating the probable fuel consumption by the degree-day method is: F = U X N x D x Ci (4) where F = fuel consumption for the estimate period. U = unit fuel consumption, or quantity of fuel used per (degree-day) (building load unit). N = number of building load units (when available use calculated hourly heat loss instead of actual amount of radiation installed). D = number of degree-days for the estimate period. Ci = temperature-correction factor from Table 3. Values of N depend on the particular building for which the estimate is Estimated Fuel Consumption for. Space Heating ' 451 Table 2. Average Monthly, and Yearly Degree-Days for Cities in the United States and Canada*- *> * (Base 65F) A ug. Y flTAoRtLaTl State Station X EARS No. OP . ** Sea sons D i e oa CQ o Z Q fci<. aa f<fl 95. *< S s g *- Anniston.............A Birmingham ...A Mobile................. A Mobile................. C Montgomery.......A Montgomery.......C Flagstaff.............. A Phoenix................. A Phoenix................ C Yuma.................... A Ark-- Bentonwill............ 06/07-40/41 Fort Smith.......... A Little Rock......... A Calif... Eureka................ C Fresno................. A Independence....... 98/9^-40/41 Los Angeles....... A Los Angeles....... C Needles................... 17/18-88/39 98/99-40/41 Red Bluff...........A Sacramento......... A Sacramento.........C San Diego........... A San Francisco.. .A San Francisco.. .C San Jose......... ..C Colo... Denver................ A Denver................ C Durango................ 04/05-40/41 Grand Junction.A LeadviUe................ 07/08-40/41 35 43 22 43 37 34 Conn. Hartford......... .`.A D. C... Washington........ A Washington........ C Fla-.., Apalachicola.......C -- Ga...... Thomasvilie.......... 05/00-40/41 36 Idaho. IU........ Springfield........... C Ind.... Evansville............A Indianapolis........A Indianapolis........C Royal Center. 18/19-31/32 14 Iowa.. Charles City.......C Davenport........... C Des Moines..........A Des Moines..........C Dubuque.............. A Keokuk.................... 98/99-41/42 Sioux City.......... A 44 0 0 17 118 438 614 614 485 381 128 25 0 2820 0 13 13 123 396 593 623 491 378 128 30 0 2780 . 0 (J (1 . 28 219 376 416 304 222 47 0 0 1612 . 0 0 . <1 23 198 357 412 290 209 40 0 0 1529 0 . 0 (1 69 304 491 517 388 288 80 0 0 2137 0 0 (1 55 267 458 483 360 265 66 0 0 1954 49 7Ji 243 586 876 1133 1231 1014 949 687 465 .212 7525 0 (] 0 22 223 400 474 309 196 74 0 0 1698 0 (1 C 13 182 360 425 278 175 62 0 0 1492 0 0 fl 0 105 259 318 167 88 14 0 0 951 1 1 33 216 516 810 879 716 519 247 86 7 4030 0 (J S 131 435 698 775 `571 418 127 24 0 3188 0 (1 1(1 110 405 654 719 543 401 122 18 0 2982 267 249 264 335 411 508 652 465 493 432 375 282 4632 0 0 n 86 345 580 629 400 304 145 43 0 2532 0 0 28 216 512 778 799 619 477 267 120 18 3834 81 22 56 87 200 301 878 305 273 185 121 56 2015 0 0 17 41 140 253 828 244 212 129 68 19 1451 0 0 fl 19 217 416 447 243 124 26 3 0 1495 350 336 263 282 317 426 467 406 437 413 415 ,363 4474 0 0 0 59 319 564 617 423 336 177 51 0 2546 0 0 22 98 357 595 642 428 348 222 103 7 2822 0 0 17 75 321 567 614 403 317 196 85 5 2600 11 7 24 52 147 255 817 247 223 151 97 43 1574 144 136 101 174 Bit 487 580 398 878 327 264 164 3421 189 177 110 128 237 406 462 336 317 279 248 180 3069 7 11 26 97 270 450 487 342 308 229 137 46 1410 5 11 120 425 771 1032 1125 924 843 525 286 65 6132 0 5 103 385 711 958 1042 854 797 492 266 60 5673 25 37 201 535 861 1204 1271 1002 859 615 394 139 7143 0 0 36 333 792 1132 1271 924 788 402 143 23 5796 280 332 509 841 1139 1413 1470 1285 1245 990 740 434 10678 0 0 74 383 771 1051 1104 865 775 456 203 27 5709 0 14 101 384 699 1082 1178 1050 871 528 201 31 6139 0 18 93 363 663 1026 1113 1005 865 567 261 52 6Q26 0 0 37 237 519 837 893 781 619 323 87 0 4333 0 0 32 231 510 831 884 770 606 314 80 0 4258 0 0 0 17 154 304 362 263 184 33 0 0 1307 0 0 0 16 148 309 881 247 169 23 0 0 1243 0 0 0 11 129 276 303 226 154 14 0 0 1113 0 0 0 0 0 22 34 25 8 0 0 0 89 0 0 0 0 0 18 28 24 7 0 0 0 77 0 0 0 0 8 62 58 48 12 0 0 0 178 0 0 0 0 5 48 67 48 15 0 0 0 173 0 0 0 18 177 334 383 275 203 45 0 0 1435 0 0 0 0 60 163 201 148 102 0 0 0 674 0 0 9 no 393 614 632 512 404 133 20 0 2826 0 0 8 107 387 611 632 515 392 135 24 0 2811 0 0 0 59 282 494 521 412 308 62 0 0 2138 0 0 0 63 280 481 497 391 275 62 0 0 2049 0 0 0 38 225 412 424 330 238 43 0 0 mo 0 0 2 48 208 361 359 299 178 52 5 1 1513 0 0 0 0 135 133 389 406 762 1054 1169 747 961 106(1 868 815 719 453 663 m 249 222 92 5890 68 5483 0 0 0 0 183 28 487 161 873 1184 1333 1022 492 784 m 683 880 523 561 182 317 47 136 0 6976 3756 0 0 90 35(1 765 1147 1243 1053 868 507 229 58 6310 0 11 8ft 339 759 1128 1240 1028 828 435 192 41 6087 0 6 83 315 723 1066 1166 958 769 404 171 32 5693 0 0 56 259 666 1017 1116 907 713 350 127 14 5225 0 0 59 215 570 871 939 770 589 251 (J 6 4360 0 17 107 377 759 1122 1200 1036 874 516 226 53 6287 0 0 79 306 705 1051 1122 938 772 432 176 3<J 5611 0 0 59 247 642 986 1051 893 725 375 140 16 5134 11 19 116 373 740 1104 1239 976 860 502 245 54 6239 0 5 77 295 681 1023 1107 913 725 371 145 24 5366 17 30 151 444 912 1352 1494 1240 1001 537 256 70 7504 0 7 79 320 756 1147 1262 1044 834 432 175 35 6091 5 12 99 365 798 1203 1330 1092 868 438 201 45 6446 0 6 89 346 777 1178 1308 1072 849 425 183 41 6274 8 28 149 444 882 1290 1414 1187 983 543 267 76 7271 1 3 71 303 680 1077 1191 1025 761 397 136 18 5663 8 17 128 405 885 1290 1423 1170 930 474 228 54 7012 Data for United States cities from a publication of the United States Weather Bureau, Monthly Normcl Temperatures, Precipitation and Degree Days, 1954 are for the period 1921 to 1950 inclusive. Those United States cities for which yeare are given in Column 3 are not listed in the above publication and the data are those which were computed by the United States Weather Bureau in 1946 and 1947 in accordance with the requirements of the National Joint Committee on Weather Statistics. Data for airport stations, A, and city stations, C, are both given where available. * Data for Canadian cities were computed bv the Meteorological Division, Department of Transport from normal monthly mean temperatures, adjusted lor the summer months by a method described by H. C. S. Thom, The Rational Relationship between Heating Degree Days and Temperature, Monthly Weather tleoiea, VoL 82, No.-1, January, 1954,