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166 CHAPTER 12 1959 Guide Table 10 .... Summary of Heat Losses of Uninsulated Residence (Bfu Per Hour) Soon or Space Walb and Root floor don and Door tefif- Totals Bedroom A Bedroom B Bedroom C Bedroom D 5520 3620 2650 2740 7410 5000 3800 3240 1440 2180 16,550 1440 1470 11,530 970 1260 8,680 960 720 950 8,610 Bathroom 1 Bathroom 2 Living Room Dining Room 690 1640 7480 3850 1620 1060 500 630 3,440 320 320 400 3,740 1800 5400 14,680 3100 3080 10,030 Kitchen Lavette Entrance Hall Garage Recreation 2920 3060 900 -960* 840 2560 -1280" 950 2300 6,170 1100 . 550 4,710 640 1600 5,700 1060 3710 1910 4,440 570 720 2890 5,020 Design Totals Operating Totals* Percentages- 34,950 23,410 34,950 ^23,410 38.4 25.8 2,910 17,410 24,620 103,300 2,910 17,410 12,310 90,990 3.2 19.1 13.5 100.0 Willhot kM<rf 1180 Btiih minui vail beat gains of 1290, 700, and 1160 Btuh. * Heat gaiaa of 960 and S20 Blob. ' Baaed on H computed infilfemtion. - Baaed oa ormtipg totala. Table 11 .... Summary of Heat Losses of Insulated Residence (Bfu Per Hour) Room or Spoca Walls CdGng and Roof Boor Gfaa Door fnfif- Total* Bedroom A Bedroom B Bedroom C Bedroom D 2480 1620 1190 1230 2460 1660 1260 1080 1440 2180 8,560 1440 1470 6,190 970 1260 4,680 690 720 950 4,670 Bathroom 1 310 540 500 630 lj980 Bathroom 2 760 250 220 320 400 1,950 Living Room 3370 1800 5400 10,570 Dining Room 1730 3100 3080 7,910 Kitchen Lavette Entrance Hall Garage Recreation 1320 1390 410 -470* 840 850 -910* 950 2300 4,570 1100 550 3,040 640 1600 3,500 1060 3710 1910 5,300 570 720 2890 5,020 Design Totals Operating Totals* Percentages- 16,180 7,190 16,180 7,190 29.1. 12.9 2,540 17,410 24,620 67,940 2,540 17,410 12,310 55,630 4.6 31.3 22.1 100.0 * Wall beat Ion of W0 Btiih wall beat gains of 590, 220, and 640 Btuh. b Heat gains 630and 220 Btuh. 'BaaedonHoomputed infiltration. - Baaed on operating totals. REFERENCES 1H. C. S. Thom: Revised winter outside design temperatures (ASHAE Transactions, Vol. 63, 1957, p. 111). *M. K. Thomas: A method for determining winter design temperatures (ASHAE Transactions, Vol. 61, 1955, p. 387). * A. P. Knits and 8. Kqnso: Investigation of Oil-Fired Forced Air Furnace Systems tncne Research Residence (University of Illinois, Engineering Experiment Station Bulletin No. 318). 4 A. P. Krats, W. S. Harris, M. K. Fahnestock, and R. J. Martin: Performance of a Hat-Water Heating System in the I-B-R Research Home at the University of Illinois (University of Illinois, Engineering Experiment Station Bulletin No. 349). * A. P. Krats and W. S. Harris: A Study of Radiant Baseboard Heating tn the I-B-R Research Home (University of Illinois, Engineering Experiment Station Bulletin No. 358). * W. 8. Harris: Performance of a One-Pipe Steam System in the I-B-R Research Home (University of Illinois, Engineering Experiment Station Bulletin No. 383). *G. L. Larson, D. W. Nelson, and John James. ASHVE Research Repost No. 1011--Tests of three heating systems in an industrial type of building (ASHVE Transactions, Vol. 41. 1935, p. 185). ' F. A. Joy, J. J. Zabrony, and S. Bhaduri: Insulating Value of Reflective Elements tn an Attic Under Winter Conditions (Peon* sylvsnia State University, October 1956). * F. A. Joy: Improving attic space insulating values (ASHAE Journal Section, Heating, Piping and Air Conditioning, Janu ary 1958, p. 223)! " F. B. Rowley, A. B. Aigren, and C. E. Lund: Methods of Moisture Control and Their Application to Building Construc tion (University of Minnesota, Engineering Experiment Station. Bulletin No. 17). M F. C. Houghten, S. I. Taimuty, Carl Cutberlet, and C. j. Brown: ASHVE Research Repost No. 1213--Heat loss through basement walls and floors (ASHVE Transactions, VoL 48,1942, p. 369). u R. 8. Dill, W. C. Robinson, and H. E. Robinson: Measure ments of Heat Losses from Slab Floor (U. S. Department of Commerce, National Bureau of Standards, Building Materials and Structures Report BMS 103). "H. D. Bareither, A. N. Fleming, nH B. E. Alberty: Tem perature and Heat Loss Characteristics of Concrete Floors Laid on the Ground (University of Illinois, SttioII Homes Council Technical Report). " Concrete Floors for Basementless Houses (University of Illinois, Small Homes Council Circular No. F 43). "J. R. Jamieson, R. W. Roose, and S. Kongo: Warm-air perimeter heating. Part HI--Heat losses iroin floor rfah (ASHVE Transactions, Vol. 58,1952, p. 217). " Warm-Air Perimeter Healing (National Warm Air Heat ing and Air Conditioning Association, Manual 4). " Siab-on-Ground Construction for Residences (Building Re search Advisory Board, National Research Council, Publica tion No. 385). " Heat Requirement Tables for Intermittently Healed Bidd ings (A. and M. College of Texas, College Station, Texas, En gineering Experiment Station Bulletin No. 60) contains a set of tables applicable to either intermittent heating or cooling. Further information may be found in a paper byE. G. Smith: A method of compiling tables for intermittent heating (ASHVE Journal Section, Heating, Piping and Air Conditioning June 1942, p. 388). CHAPTER 13 COOLING LOAD Cooling Load Calculations; Design Conditions; Instantaneous Heat load; Solar Radiation; Periodic Heat How; Tables for Calculating Solar Heat Gain Through Walls, Roofs, and Glass; Instantaneous Heat Gain vs. Cooling loods; Load from Inferior Partitions, Ceiling, and Floors; Load from Outdoor Air, Ventilation andInfiltration; Effect of Outdoor Air on Load; Heat Sources Within Conditioned Space; Moisture Transfer Heat Load; Miscellaneous Heat Loach; Apparatus Dew Point and Required Air Quantity Through Conditioning Equipment; Minimum Entering Air Temperature; Example Cooling Load Calculation THE variables affecting cooling load calculations are numerous, often difficult to define precisely, and always on the type of structure; (2) load due to heat gain through interior partitions, ceilings, and floors; (3) load due to ventila tion, either natural or mechanical; (4) load due to heat sources intricately interrelated. Most of the components of the cooling within the conditioned space such as people, lights, power load vary in magnitude over a wide range during a 24-hour equipment, and appliances; (5) load due to moisture transfer period, and as the cyclic changes in load components are not usually in phase with each other, careful analysis is required to establish the resultant marimnm cooling load for a building through permeable building materials; and (6) miscellaneous heat sources. C- Determination of Air Quantity and Apparatus Dew Point. or tone. A coned system must often handle peak loads in These factors will be discussed in turn. The material pre different zones at different hours. sented leads to an illustrative procedure for a cooling load Economic considerations must be of particular influence in calculation, and a numerical example is given to demon the selection of equipment for cooling season operation in strate the calculations involved. comfort air conditioning, and this fact, coupled with present inadequacies in available data and knowledge of the air- DESIGN CONDITIONS conditioning art, places a premium on the experienced judg ment essential to successful design or practice. Variations in Indoor Conditions the weather, building occupancy, and other factors affecting Indoor air conditions for human health and comfort have load, necessitate carefully coordinated controls to regulate .. been and continue to be the subject of much discussion and simultaneously the components and the equipment in order ' research. to maintain the desired room conditions. The effective temperature index, explained in Chapter 6, is The calculation procedures presented in this chapter deal probably the best available source of design criteria for com with the various instantaneous rates of heat gain, both sen fort air-conditioning systems for buildings or enclosures in sible and latent, in a conditioned space. There may be an which the air and inside surface temperatures remain sub appreciable difference between the net instantaneous rate of stantially equal; a condition that can safely be assumed for heat gain and the total cooling load at any instant. This differ most ordinary comfort air-conditioning installations. Other ence is caused by the storage and subsequent release of heat sources of design specifications are to be found in the require by the structure and its contents. This thermal-storage effect ments of codes ordinances, and in the varied long-term may be quite important in determining an economical cooling experiences of manufacturers, contractors, and engineering equipment capacity. The lack of any adequate mftftna of specialists. treating this storage quantitatively in its entirety for a com Past experience, cumulative over many years, indicates that plete structure, must be recognized in judging the procedures indoor design conditions, for which summer air-conditioning and data presented for calculating individual components of equipment is selected, should not exceed a temperature of tiie net rate of instantaneous heat gain. 80 F or a relative humidity of 50 percent for the average job Solar heating calculations involve the Ramp principles as in the United States. If these conditions are exceeded, com cooling load calculations. Many of the data on solar radiation plaints of discomfort may be expected, especially with con given in this chapter can be used in calculations for solar tinuous occupancy. For very brief occupancy only, a slightly heating. higher peak-load design temperature may be employed. In regard to the lower limit of humidity, complaints are not COOLING LOAD CALCULATIONS encountered for store installations operated down to 35 Summer cooling load calculations, whether for industrial or comfort applications, require consideration of the follow ing factors: percent relative humidity or, for office jobs, somewhat lower. These observations apply to normal commercial practice in this country only. For extremes, such as tropical or very hot regions, it is regarded as more practicable to design for a A. Design Conditions: (1) indoor conditions; (2) outdoor conditions; (3) ventilation rate. B. Instantaneous Heat Load, Sensible and Latent: (1) load from solar radiation, sky radiation, and from outdoor-indopr tenmerature differential for glass areas and exterior walls and roofs, modified by periodic heat flow or lag factors depending peak-lead outdoor-indoor temperature difference of about 15 to 20 F deg. Table 1 offers typical design conditions for average require ments encountered. The values in line 1 would also apply in general for localities having a summer outdoor design tem- 167