Document JEB1G9reaE8MLnEjNNmK23MO

386 CHAPTER 20 1946 Guide Table 6. Steam Consumption of Buildings with Various Types of Occupancy Type op Building No. Bldgs. Office............................................. ......... Office and Bank.___________________ Office and Printing......... ................. Office and Theater. ......... .......... Office and Stores or Shops Bank......... ............ . Department Store .. Stores.-- . ____ ____________ Loft......... ........................ Warehouse.--......... Hotel and Club......... Apartment or Residence Theater........................ ..................... Garage.______ ___ Manufacturing. Church. ..... ......... HospitaL __ ____ ___ School____ ___ _ Municipal or Federal.... Lodge, Gym, Hall or Auditorium____ Miscellaneous--. .... .................... Total or Average . 334 49 8 7 26 16 63 73 63 24 73 51 22 13 19 9 .4 8 15 12 7 896 Average Volume Heated Space 1000 Cu Ft 2160 3000 1895 4950 1615 806 3400 . 310 865 2230 1795 1425 1240 1540 1350 656 3306 1115 3215 880 1387 1890 Steam for Heating Lb per DD per 1000 Cu Ft Average Hours of Occupancy 0.685 0.577 1.230 0.412 0.617 0.786 0.385 0.624 0.588 0.459 0.990 0.962 0.482 0.202 0.808 0.532 1.194 0.592 0.587 0.390 0.479 12.1 13.1 17.7 12.9 13.2 11.7 11.1 10.4 10.0 9.4 22.3 21.8 12.9 21.4 ; 9.5 7.9 22.0 11.5 15.6 12.4 21.4 0.651 13.4 "Principles of Economical Heating. National Association of Building Ovmers and Managers. variable, indicates whether the operating efficiency of the plant is above or below the previous month or year. The figures in Table 7 illustrate a typical example of a method of using the degree-day for making heating comparisons for one building for two consecutive heating seasons. The heat quantity figures inserted are pounds of steam, but a similar comparison could be made using pounds of coal, gallons of oil, or cubic feet of gas. For such a comparison, a two-year record is often used, as shown in Table 7. The year under consideration may then be compared, month by month, with the previous year; Column 3, Consumption for Heating, would be used if the same fuel is used for heating and process steam. Some reasonable figure must be assumed for the process requirement and should be deducted from the amount shown in column 2. This would leave in column 3 only the fuel chargeable to heating. The degree-day values in column 5 are obtainable from the local Weather Bureau. Figures in column 6 are obtained by dividing corresponding values in column 3 by the degree days in column 5. The heating index in column 6 is, then, a figure of heat consumption, corrected for outdoor temperature, and should be relatively constant month by month. Column 7 in Table 7 may be used if the heat consumption is to be compared on a building volume basis with average values shown in Table 6. 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 Estimating Fuel Consumption for Space Heating ' 387 Table 7. Heat Consumption Record for Comparison Col. 1 Col. 2 Col. 3 Consumption Consumption For Heating Sept- ........ Oct.._ ___ Nov............ Dec............. Jan_ ___ Feb............. Mar............. Apr- _ ... May............ June............ July------- .... Aug........ -- 337,500 834,200 1,446,600 2,176,400 2,332,200 2,131,100 2,021,900 1,241,500 672,500 258,600 188,400 180,100 13,821,000 Sept.______ 330,200 Oct.. 887,100 * Nov....... ..... 1,525,200 Dec.....: 2,045,500 5 Jan.............. 1,933,400 Feb.............. 1,990,200 Mar 1,984,100 170,500 667,200 1,279,600 2,009,400 2,165,200 1,964,100 1,854,900 1,074,500 505,500 91,600 ......... ..... ........ ...... 146,200 703,100 1,341,200 1,861,500 1,749,400 1,806,200 1,800,100 Col. 4 Avc. Mean Temp. 65 53 44 25 22 28 31 43 55 61 52 39 28 30 30 31 Col. 5 Dec Days 65 F Base 146 339 641 1,233 1,297 1,106 1,032 647 303 50 Col. 6 Lb/Deg Day 1,170 1,966 1,990 1,630 1,670 1,775 1,799 1,660 1,670 1,830 Col. 7 Lb/Deg Day/ M Cu Ft 0.575 0.970 0.982 0.804 0.822 0.888 0.885 0.818 0.822 0.905 167 410 812 1,120 1,044 1,111 1,021 875 1,718 1,653 1,660 1,670 1,624 1,760 0.431 0.845 0.815 0.817 0.825 0.800 0.868 If. for example, the heat-consumption in March, 1943, is compared with that in March, 1944, it will be found that in the latter the steam consumption is 1799 -- 176Q = 39 lb less which is a decrease of 2.2 per cent. be measured in several different ways. It may be taken as the instan taneous 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 are available for a number of buildings in Detroit, as shown in Table 86. These maximum demands were measured by an attachment on the condensation meter and therefore represent the. amounts of condensation 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 maximum load and is an index of the utilization. Thus, in Table 8, 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. SEASONAL EFFICIENCY The task of predicting fuel consumption within reasonably accurate limits is a simple one where sufficient experience data are available for the fuel in question. Such data can be analyzed to the point where average unit factors can be determined and expressed in such terms as, for example, average gallons of oil actually burned per square , foot of calculated steam radiator surface per degree-day. The unit U can be inserted directly in Equation .2 without reference to efficiency. Such experience factors are available for gas (see Table 2). and for district steam (Table 6), but not for coal or oil. Since values of U are not available for oil or coal; an assumed seasonal efficiency E must be used. Selection of a value for this E must be made y