Document D6dNa9ZpJdBqjQZJQ8EwLmGM

436 CHAPTER 18 1953 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 maximum 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 Caiiadian Meteorological Division of the Department of Transport, and were computed from the mean tem perature normals on record for the various stations. , 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: where F^UXNXDXC, (4) 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. ' Ct = temperature:correction factor from Table 3. Values of N depend on the particular building for which the estimate is Estimating Fuel Consumption for. Space Heating 437 Table 2. Average Monthly and Yearly- Degree-Days for Cities in the United States and' Canada*-b (Base 65F) N O . OF 1 Sea sons i Statd Station Yeabs 53 i* g 6 p E 'H < 00 $ o Z s Q -> ri H to IS 4 s Mo < 4 s M 2 >P-> B (4 Bh >* Ala.... 05/06-40/41 36'. >8/99-45/46 48 0 0 10 135 388 600 609 513 361 152 37 1 . 2806 0 1 10 111 348 ''586- 591 497 313 130 23 ' 1 2611 >8/99-45/46 >8/99-45/46 98/99-40/41 48 48 43 , o! 0 1 44 203 377j 397 314 175 52 .3 0 0 0 4 71 279 484' 494 405 239 85 10 0 43 70 244 573 847 1111 1167 970 889 668 469 190 1566 2071 7241 Calif... Phoenix............. 98/99-45/46 98/99-40/41 45/46 >8/07-40/41 Fort Smith.... .A >8/99-45/46 Little Rock........A 98/99-45/46 98/99-45/46 >8/99-45/46 48 0 0 0 18 166 384: 402 263 154 47 7 0 , J44 0 0 0 9 113 306 318 182 85 22 1 o 35 1 1 38 216; m 810 879 716 519 247 86 7 48 0 0 12 128 410 717 763 615 .390 154 36 1 48 0 0 11 120 383 668 704 579 367 145 31 1 48 ' 281 269 274 344 411 518 541 478.. 504 440 391 307 48 0 0 5 77 309 562 573 380 289 152 52 , 4 1441 1036 4036 3226 3009 4758 2403 Independence___ >8/99-40/41 43 0 . 0 28 216 612 778 799 619 477 267 120 :18 . 3834 >8/99-45/46 48 1 0 5 43 110 225 272 235 212 158 103 `27 1391 17/18-38/39 22 0 . 0 0 19 217 416 447 243 124 26 3 0 1495 Point Reyes.......... 98/99-40/41 43* 350 336 263 282 317 425 467 406 437 413 416 363 4474 Red Bluff...........A >8/99-33/34 38/39-40/41 44/45-45/46 41 0 0 12 97 345 692 601 419 328 178 .72 ,. 9 2653 Sacramento........... 98/99-45/46 98/99-45/46 98/99-45/46 96/07-40/41 Denver................... 98/99-45/46 94/05-40/41 07/08-40/41 Pueblo................. A 98/99-45/48 Conn.. Hartford............. A'04/05-45/46 98/99-45/46 D. C.. Washington........... 98/99-45/46 Fla.... Apalachicola'.----- 13/14-45/48 Jacksonville.......... 98/99-45/46 Key West............... 98/99-45/46 Miami................ 11/12-45/46 13/14-45/46 Tampa............A 98/99-45/46 Ga. .; 98/99-45/46 98/99-45/48 99/00-45/48 Savannah...........A 98/99-45/46 Thomasvilie.......... 05/06-40/41 Idaho.. Boise.................... A 98/99-45/46 00/01-32/33 98/99-45/46 Ill......... 98/99-45/48 Qfi/99--45/48 48 2 1 15 98 332 582 695 .405'326 202 101 ,21 2680 48 5 1 9 60 143 252 300 257) 230 172 118 49 1596 ill48 196 179 121 139 241 420 460 340 272 255 197 3137 35 21 21 52 151 329 512 627 383 339 249 167 .72 2823 48 8 8 126 411 716 1005 1023 897- 790 516 275 64 5839 37. . 25 37 201 535 861,1204 1271 1002 859 615 394 139 7143 48 1 1 59 347 743 1138 1218 883 671 3771 152 23 5613 34 280 332 509 841 1139 141311470 12S5 1245 990i 740 .434 10678 48 3 4 91 377 730 1042[1042 875 724 446 195 .29 5558 42 3 16 105 370 692 1065 1157-1062 859 524 213 47 6113 48 3 11 86 341 658 1017 1109 1023 840 522 221 47 5880 48 0 2 42 251 553 872 928; 834 1 624 34C 101 14 4561 33 ' 0 0 . 1 23 154 300 323 Z52 159 3* 2 0 1252 48 : 0 C . 0 25 144 294 302 244 131 42 3 (J 1185 48 0 6 0 0 2 14 21 15 7 O (1 (J 59 35 0 C 0 0 15 41 53 45 28 : t t 185 33 48 0 l 25 159 305 332 255 |62 31 4 C 1281 0 ( C 6 60 149 157 126 ! 62 11 C C . 571 48 48 0 0 t 12 128 3^ 644 65C 563 382 161 0 * 85 312 529 5331 448 ' 274 10i 33 Vi 2 2985 1 2306 47 C ( * 91 322 1 532 538 449 . 278 10* 14 . 1 2338 48 0 ( 1 45 206. 390 395! 332| 194 6* 6 ( 1635 36 (J ( i 48 208 361 359 299. 178 52 5 1 1513 48 .9 Vi 13* 385 717 1025 1077) 840. 688 44( 251 92 . 5678 33 i i 107 378 688 932 992 779! 603 37! 19: 52 6109 48 . 12 21! 17* 475! 821 1159 1224 1004; 845 55* 33( 12' 6741 48 C ( 2* 181 493 823 87* 7481 512 232 6* . i 3957 48 'fi 5 , 8* 3371 712 111* 1218 1080) 861 531 259 67 6282 41 4 8 8> 35( 730 112* 1231 1035! 790 .28 6004 Ind.... Iowa .. Kan... Ky... La.... He.... Springfield............. 88/99^-45/4* 48 : Evansville..........A 98/99-45/4* -48 Fort Wavne... A 11/12-45/4* 35 198/99-45/4* ' 48 18/19-31/32 14 ! 12/13-45/4* 34. Charles City......... 04/05-45/4* 42 Davenport............. 98/99-45/46 48 98/99-45/4* 48 98/99-45/4* 48 Keokuk.............. 98/99-41/42 44 Sioux City........./ 98/99-45/46 48 98/99-45/44 48 98/99-45/41 48 IolaT...................... 05/06-40/4 36 98/99-45/41 48 98/99--45/41 48 Louisville............. 98/99-45/41 48 98/99-40/4 43 98/99-45/48 48 . 98/99-45/41 48 Eastport............... 198/88--45/41 48 C i : 65 . 28* 664 1056 , 977| 719 . 16 c ! 31 211-544 88* ' 948 822! 582 6 e i; 106- 374 737 1107 1211 1052j 864 41 i - 61 293 , 660 1032 1102 973! 737 410 154 22 iu 1! 116 37: i 740 1104 1239 976 860 502 245 64 * 62 270 6271 993 1072 897, 687 358 133 15 * 2` 164 48* ; 9061362 1635 1281! 995 652 255 62 2 ( ' 91! 344 748 1176 1291 lllll 835 448, 171 291 ] . < 102. 35- 76711204,1320 1132. 843 446 171 29 < 12 123j 402 808 1249,1380 1190; 915 493 204 41 ] : 7 30: 680 1077)119 1025) 761 3971 136 18 < i 128 402 844 1273(1402 1206! 909 485 202 40 ] i 6f 281 670 106011144', 9541 712 365 142 .18 : 59l 27S 64ll 998|l046l 868| 668 3511 1391 .20 ( 40 231 579: 931 1026 8I7| 599 * i 5fl> 25- 623 1015 1096, 917| 659 326! 116 ( 411 22 576, 947 101* 8343 604 290, 103 7 1 35 213 549! 88 93 816' 588 298 93 1 !A 48 258 601 91' 96 862 650 352 123 14 < 25 145 304 32.1 247| 129 10! 0 \ 01 1 7 275 60* 531 4151 241 0 ibi 146 27 1 625 827 1224 1364^1238 1080 530, 301 6446 4410 6232 6458 6239 6117 7624 6262 6375 6820 6663 6906 5426 5069 4616 5075 4644 4417 4792 1203 2132 6445 Md... Greenville........... 07/08-40/4 42/43-45/4* Portland............. A 98/99-45/4 Baltimore............. j98/99-45/4* 38 48 48 1 1012l1464^1625l1443 1251 6t 113 31 S 64 2 48 182 46 794 1182 1309 1188 997 l 1| 33| 22' 526| 855 921 837| 637 468 194 9439 376 136 7377 95t 12j 4487 * Computed from daily temperatures recorded by United States Weather Bureau stations over a varied number of seasons as indicated in the 3rd and 4th column of the table. Degree-day data for airport stations are not included in this table. The date for United 8tates cities were computed by the United States Weather Bureau in 1946 and 1947 in accordance with the requirements of the Natumal Jcnnt Com mittee bn Weather Statistics. The data for a number of the cities listed are based on readings taken at more than one official city weather station during the periods of analysis, but the alight difference in the readings would not appreciably affect the resultant. Letter A indicates city office and airport records combined./