" 'H. pr‘ HEAT TRANSMISSION THROUGH , FARM BUILDING METAL ROQ'FS? ' UNDER SUMMER commons r Thesis for the Degree of M‘ S. Mi-CHIGAN STATE UNIVERSITY ILSE VIERMA DE TRUJI‘LLO 1-971 0 a at?“ “MARY ‘ mchigan Stat: University 5:": . '2’”. ‘- amoma 37 V HMS & ‘SUNS' A1 “ 5995-!!UQEFXJflfi- ”SEX ABSTRACT HEAT TRANSMISSION THROUGH FARM BUILDING METAL ROOFS UNDER SUMMER CONDITIONS BY Ilse Vierma de Trujillo The objective of this study was to evaluate the sol-air temperature equation of heat flow into open live— stock buildings in hot climates. Roof, air and globe temperature measurements were made under Michigan condi- tions. Venezuelan climatic data were also used for calcu- lations of possible radiation heat loads under trOpical conditions. Michigan tests were conducted in the Michigan State University Beef Cattle Research Center. A section of the East-West oriented wing of the cattle barn was used for the environmental measurements. The South side of this gable roofed structure was cpen and the North side had continuous mobil-type windows. The sol-air temperature approach is a computation method designed to include the radiant heat load on an exposed surface and the resulting heat transfer through that exposed roof or side wall. The sol-air method was Ilse Vierma de Trujillo evaluated in this study by measure roof surface tempera- tures, air temperatures, air velocities and black-globe temperatures. Heat flow calculations based upon these measurements were compared to sol-air computations. Solar radiation intensity data were obtained from the Michigan State University meteorological station lo- cated about one mile from the test building. Environmental measurements were made during the higher temperature hours (10:00 a.m. to 4:00 p.m.) of a few days in September of 1970 and June of 1971. One Black-globe thermometer was located outside of the cattle building and three inside at heights of 3, 6 and 10 feet. An analysis was also made of the possible justifi- cation for insulation of metal roofs for minimizing the heat stress on the housed animals during hot weather. Tests were not made in this study to confirm any possible advantages. Approved WM i Majbr Professor Approved Department Chairman HEAT TRANSMISSION THROUGH FARM BUILDING METAL ROOFS UNDER SUMMER CONDITIONS BY Ilse Vierma de Trujillo A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Agricultural Engineering 1971 A 103 amigos, a mis padres, a Gustavo y Valentina. ACKNOWLEDGMENTS The author wishes to express her sincere apprecia- tion to Professor Merle Esmay, Agricultural Engineering Department who provided counsel, guidance and encouragement throughout the entire-study period and during the investi- gation and preparation of this manuscript. Appreciation is likewise extended to: Dr. Charles Barr and Dr. George Merva, members of her guidance committee. To Professor E. H. Kidder for providing the solar radiation data. To Dr. Richard Phillips for his assistance with the instrumentation phase of the research.‘ To Dr. Manuel V. Benezra, Dean of the Agronomy Faculty U.C.V. for providing the solar radiation data from Venezuela. To the Facultad de Agronomia de la Universidad Central de Venezuela and Consejo de Desarrollo Cientifico y Humanistico, U.C.V. for the financial support and for providing the necessary leave which made it possible for the author to undertake graduate study. And finally the author is very thankful to the Faculty, staff and graduate students from the Agricultural iii Engineering Department for their friendship and hospitality that made her stay in a foreign country more pleasant. To my classmates in Room 13, thanks to all of you. iv TABLE OF CONTENTS Page LIST OF TABLES o o o o o o o o o o o o o o o o o o o Vii LIST OF FIGURES . . . . . . . . . . . . . . . . . . . x 1. INTRODUCTION . . . . . . . . . . . . . . . . . . l 2. REVIEW OF LITERATURE . . . . . . . . . . . . . . 5 2.1 Heat Loss by Convection . . . . . . . . . 5 2.2 Heat Loss by Evaporation . . . . . . . . . 6 2.3 Heat Loss by Conduction . . . . . . . . . 7 2.4 Heat Loss by Radiation . . . . . . . . . . 7 2.5 Radiant Heat Load on an Animal . . . . . . 7 2.6 The Use of a Shade for Environmental Control . . . . . . . . . . . . . . . . . 8 2.7 Orientation of Shade . . . . . . . . . . . 9 2.8 Shade Size . . . . . . . . . . . . . . . . 10 2.9 Shade Height . . . . . . . . . . . . . 10 2.10 Animal Location Under the Shade. . . . . 11 2.11 Shade Materials . . . . . . . . . . . . . 12 2.12 Types of Shade . . . . . . . . . . . . . 14 2.13 Effect of Surrounding Objects on an Animal' s Radiant Heat Load . . . . . . . . 15 3. FACILITIES AND EQUIPMENT . . . . . . . . . . . . 17 3.1 The Building . . . . . . . . . . . . . . . 17 3.2 Equipment . . . . . . . . . . . . . . . . l7 4. THEORETICAL ANALYSIS . . . . . . . . . . . . . . 25 4.1 Sol-air Temperature "t " . . . . . . . . 25 4.2 Intensity of Solar Rad ation "I" . . . . . 26 4.3 Angle of Incidence 0 . . . . . . . . . . . 26 4.4 Solar Altitude B . . . . . . . . . . . . . 27 4.5 Direct Normal Radiation "Idn" . . . . . . 29 4.6 Heat Flow Through the Roof "Q" . . . . . . 29 4.7 Rate of Heat Flow to the Inside "qi" . . . 30 4.8 Mean Radiant Temperature . . . . . . . . . 30 4.9 Radiant Heat Load: "RHL" . . . . . . . . 31 5 0 RESULTS 0 O O O O O O O I O O O O O O O O O O O O 5.1 Solar Altitude "B" Computations . . . . . Computations of Direct Normal Radiation . Computations of the Angle of Incidence 0 . Computation of the Intensity of Solar Radiation "I" . . . . . . . . . . . . . . Computation of the Sol-Air Temperature "te " . . . . . . . . . . . . . . . . . . Computation of the Heat Flow Through the Roof "Q" . . . . . . . . . . . . . . . . Rate of Heat Flow to the Inside qi . . . . Computation of the Radiant Heat Load .. RHL " O O O O O O O O O I O O O O O O O 0 U1 U1U1U| O O O 0‘ U1 awn U'l mm 0 O (13% 6 0 USE OF INSULATION O O O O O O O O O O O O O O O O 6.1 Computation of Decrease in the Rate of Heat Transfer Through the Roof by Using Insulating Materials . . . . . . . . . . . 7. DISCUSSION OF THE RESULTS AND CONCLUSIONS . . . . 7.1 Heat Flow Through the Roof "Q" and Rate of Heat Flow to the Inside "qi" Black Globe Thermometer Readings Radiant Heat Load . . . . . . . Use of Insulation . . . . . Roof Surface Temperature . . Conclusions . . . . . . . . \IQQQQ O‘U‘ObWN o o o o o o o o o o o o o o o o o o o o o o o o 8. COMPUTATION OF THE SOL-AIR TEMPERATURE AND HEAT FLOW THROUGH METAL ROOFS FOR OPEN FARM BUILDINGS IN TROPICAL CONDITIONS (VENEZUELA) . . . . . . . 8.1 Solar Altitude Computation . . . . . . . 8.2 Computation of the Angle of Incidence 0 . 8.3 Computation of the Intensity of Solar Radiation "I" . . . . . . . . . . . . . . 8.4 Computation of the Sol—Air Temperature“ "te " . . . . . . . . . . . . . . . . . 8.5 Computation of the Heat Flow Through the Roof "Q" . . . . . . . . . . . . . . . . . 8.6 Computation of the Inside Roof Surface Temperature . . . . . . . . . . . . . . . 8.7 Discussion of the Results . . .-. . . . . 9 O RECOWENDAT IONS O O O O O O O O O O O O O O O O 0 REFERENCES 0 O O O I O O O O O O O O O O O O O O O 0 APPENDIX 0 O O O O O O O O O O O O O O O O O O 0 C O Page 33 33 33 34 38 38 40 44 44 50 67 67 69 69 73 73 73 77 81 82 86 LIST OF TABLES Table Page 1. Thermocouple locations in test building . . . . 21 2. Incident solar radiation on a horizontal surface "Ih" for September 1, 1970 . . . . . 35 3. Incident solar radiation on a horizontal surface "Ih" for September 4, 1970 . . . . . 35 4. Incident solar radiation on a horizontal surface "Ih" for September 5, 1970 . . . . . 36 5. Incident solar radiation on a horizontal surface "Ih" for June 27, 1971 . . . . . . . 36 6. Incident solar radiation on a horizontal surface "Ih" for June 28, 1971 . . . . . . . 37 7. Direct solar radiation an a plane normal to the sun's ray (BTU/ft hr.) Idn . . . . . . . 8. Intensity of solar radiation "I" incident upon the outdoor surface (direct, diffuse and reflected) BTU/hr ft2 south facing slope. 39 37 9. Intensity of solar radiation "I" incident upon the outdoor surface (direct, diffuse and reflected) BTU/hr ft2 north facing slope. 39 10. Outside air temperature "to" (degrees F) . . . 40 ll. Sol-air temperature "te" degrees F, for the south Slope I O O O O O O O O O O O O O O O O 41 12. Sol-air temperature "te" degrees F, for the north Slope O O O O O O O O O O I O O O O O O 4 l 13. Inside air temperature "ti" (degrees F) . . . . 42 14. Rate of hgat flow through the south roof "Q" (BTU/hr ft) 0 O O O O O O O I O O O O O O O O 43 vii Table 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. Rate of heat flow through the north side roof "Q" (BTU/hr ft2). .,, . . . . . . . . . . . . Temperature of the inside roof's surface °F (south) 0 O O O O O O O O O O O O O C O O O 0 Temperature of the inside roof's surface °F (north) 0 a o o o o o o o o o o o o ‘- o o o 0 Rate of heat flow to the inside "qi" BTU/hr ft2 (south) . O . . . . . . . . . . . . . . . . . Rate of heat flow to the inside "qi" BTU/hr ft2 (north) . . . . . . C O . . C . . . . . . . . Outside black globe temperature measurement OF 0 o o o o o o o o o o o o 0 0'0 0 o o o 0 Inside black globe temperature measurement °F . Radiant heat load at 12:00 noon BTU/hr (sq ft). Rate of heat flow "Q"; BTU/hr ftz; "Qt" BTU/hr ft2 for different "R" values and decrease of heat flow in percentage . . . .‘. Seasonal declination of sun "6" and solar altitude "8" degrees for 12:00 noon and 9 a latitude North 0 O O O O O O O O O O O O 0 Angle of incidence of sun 0 for the South and North slope and (cosine 0) "K" values at 12 : 00 noon 0 I O O O I O O O O O O O O O O 0 Direct solar radiation Idn at 12:00 noon . . . Intensity of solar radiation "I" incident. upon the outdoor surface at 12:00 noon in BTU/hr (Sq ft) 0 o o o o o o o o o o c o o o c Sol-air temperature "te" at 12:00 noon °F . . . Inside air temperature "ti" °F and °C at 12 : 00 noon 0 O O O I O I O O O O O O O O O 0 Heat flow through the roof "Q" BTU/hr (sq ft) at 12:00 noon . . . . . . . . . . . . . . . . Inside surface temperature "tsi" °F at 12:00 noon 0 O O O O O O O O O O O O O I I O O O 0 viii Page 43 45 45 46 46 48 48 49 53 68 7O 71 72 74 75 76 78 I”. Table 32. 33. 34. 35. 36. 37. 38. Page Seasonal declination of sun "6" (degrees) . . . 86 Hour angle "H" degrees . . . . . . . . . . . . 86 Solar altitude "8" (degrees) for 42° 47' latitude North . . . . . . . . . . . . . . . 87 Angle of incidence of sun's ray 8 for the South facing slope . . . . . . . . . . . . . 88 Angle of incidence of sun's ray 9 for the North facing slope. . . . . . . . . . . . . . 89 Air velocity feet per minute at 12:00 noon . . 90 Black globe temperature measurements at 12:00 noon (degrees R). . . . . . . . . . . . 90 ix LIST OF FIGURES Figure 1. 2. 10. 11. 12. View from the south side of the east section building 0 O I O O O O I O O O O O O O O 0 Lateral view of the building, showing the rOOf type 0 O O O O O O O O O O O O O O O 0 Floor plan of cattle pens where Black globe thermometers were located . . . . . . . . . Cross section of East section with thermo- couples and Black globe thermometers location . . . . . . . . . . . . . . . . . Location of black globe thermometers . . . . Black globe thermometers made from ping pong balls 0 O O O O O O O O O O O O O O O O O 0 Sun angles on the roof planes of a gable- type building oriented East-West . . . . . Angle of the roof "r" with the horizontal . . Rate of heat flow through the roof "Q" and rate of heat flow to the inside qi BTU/hr (sq ft) for September 1, 1970 . . . . . . . Rate of heat flow through the roof "Q" and rate of heat flow to the inside qi BTU/hr (sq ft) for September 4, 1970 . . . . . . . Rate of heat flow through the roof "Q" and rate of heat flow to the inside qi BTU/hr (sq ft) for September 5, 1970 . . . . . . . Rate of heat flow through the roof "0" and rate of heat flow to the inside qi BTU/hr (sq ft) for June 27, 1971 . . . . . . . . . Page 18 18 19 20 23 24 28 28 55 56 57 58 -‘ _" Figure Page 13. Rate of heat flow through the roof "Q" and rate of heat flow to the inside qi BTU/hr (sq ft) for June 28, 1971 . . . . . . . . . . 59 14. Radiant heat load at 12:00 noon BTU/hr (sq ft) under the sum and inside the building at 3 and 6 feet high . . . . . . . . . . . . 61 15. Inside surface and air temperature (°F) for Jun928inMiChiganooo0000-00000 64 16. Inside surface temperature of the roof and inside air temperature at 12:00 noon for an average day of one month in tropical con- ditions (Venezuela) . . . . . . . . . . . . . 30 xi 1 . INTRODUCTION An animal's environment as defined by Bond (5) is the total of all external conditions that affect its de- veloPment, response and growth. It could include, for example, the type and slope of floor as part of the pig- let's environment. The external factors that affect the regulation and balance of animal heat are important. These climatic factors include air temperature, moisture, radiation, light and air velocity. Climatic factors directly affect production and growth of livestock and birds. First of all domestic animals are homeothermic and thus attempt to maintain a constant body temperature. Animals, like human beings, can exist only within a limited range of body temperature; they must maintain a rather delicate balance between the heat produced within their body and the heat they lose to or gain from their environment. The thermo environment surrounding the animal has a direct influence on the amount of heat exchanged. Physiological adjustments must be made by the animal to maintain a body heat balance. If the heat balance becomes unbalanced it can reflect directly on growth, production and health. Therefore, these environmental factors are of great importance in livestock and poultry production. Cold weather is the dominant environmental problem in the northern areas of North America and Europe, while in tropical countries the critical problem is hot weather. In cold weather the problem is to protect the animal from low temperatures, ventilate to remove water vapor and detrimental gases and provide enough oxygen. In hot weather regions the problem is with high air temperature, high solar radiation and high humidity (depending upon the relative humidity on the season of the year) (11). In some tr0pical areas, and that is the case in Venezuela exists two marked seasons; winter and summer. Winter season is considered the rainy season; high rain- fall, lower ambient temperature, high humidity. Summer season is considered to be the dry season; little or no rainfall; higher air temperature and low humidity (12). These climatic conditions of high solar radiation combined with high environmental wet and dry bulb tempera- tures affect animal productivity adversely. Domestic animals and chickens are affected to a greater extent than man, because man can sweat and livestock cannot (5). The body temperature for dairy cattle, beef cattle, sheep and swine is about 102°F and for laying hen 106°F (14). When body temperature surpasses these levels, due to the environment, the animals are under "thermal stress." If body temperatures continue increasing the homeothermic mechanism fails and the animal will die (5). An animal needs food to substain its metabolic life process. Part of the food is utilized by the body processes, part is lost in urine, feses and gases and part must be dissipated from the body as heat energy. The ex- cess heat must be dissipated from the body or a heat bal- ance does not exist. Air temperatures above the animal's body tempera- ture brings about some convective heat gain and tends to cause "thermal stress." Evaporation is then the only means of heat dissipation available to the animal, so it cuts down on feed intake and increases its rate of respi- ration (22). The resulting heat stress and reduced food consumption causes reductions in weight gain and other products such as milk or eggs. The main problem then in tropical climates is for animals to dissipate excess metabolic heat without unde- sirable physiological reactions. This can be enhanced by means of environmental control. Agricultural engineers have been working to improve environmental control. Any economic improvement of the thermal environment for livestock and birds may be consid- ered to be functional environmental control (8). A building is part of the animal's environment and roofing materials are part of that building. The objective of this study was to investigate the rate of heat flow through metal roofs of open livestock buildings. The sol- air temperature approach was used for analytical purposes. A second part of the study pertained to measurement of actual roof and black-bulb temperatures to check the sol- air method of analysis. The possible radiant heat load on animals was analyzed, roof insulation was considered and projected radiant heat loads under tropical conditions were made. 2. REVIEW OF LITERATURE The attainment of hot weather comfort for animals is a problem in heat transfer. Animals may dissipate heat by conduction, convection radiation and evaporation. The three basic means of heat transfer depend on the tempera- ture of the ambient air and surroundings (22). Evaporation depends on the vapor pressure differences between the ambient air and evaporative surfaces. 2.1 Heat Loss by Convection Temperature differences and air velocity directly effect convective heat losses. Cooling can be done by air conditioning equipment, and velocity increased by using fans. According to Bond (8) complete environmental con- trol can be accomplished only with a well—designed air conditioning system. Air conditioning systems for live— stock have not been economically practical; and there are dust filtration problems if the air is recirculated too much along with ammonia accumulation. The idea of partial air conditioned system was tested by Hahn, 32 El. (19). Only the air inspired directly by dairy cows was cooled as an alternative to total air conditioning. An increase in feed intake and milk production resulted. They concluded, however, that cows will produce more and eat more while under less physiological stress due to the improved heat dissipation when breathing cooled air in a hot environment, but that only total environmental control would provide maximum production and relief from heat stress. 2.2 Heat Loss by_Evaporation Low humidity air is advantageous for evaporative cooling because it maximizes vapor pressure differences and the potential for absorbing moisture from the wetted surfaces of an animal. Evaporative heat loss can continue in hot weather when air temperatures are above body temp- erature so is beneficial in summer conditions (13). Water sprays have been used to cool the animals. Kelly and Ittner (22) used sprays under aluminum shades to wet beef cattle. Cattle made little use of the shower until they were changed from a mist spray to a more wetting shower. The showers were modified to provide a coarse spray and the head of the shower was brought down to within 6 feet of the floor. The coarse spray soaked the cattle and caused a drop in respiration rates and body tempera- tures. Wetted animals quite often had body temperature reductions of 2 or 3 degrees, and respiration rate drops of 20 or more per minute within one half hour after wetting. Water sprays have also been used on birds. The main benefit has been to reduce mortality from heat pros- tration. Little benefit to egg production or broiler growth was found by Wilson, 23 31. (33). 2.3 Heat Loss bngonduction Heat dissipation from animals may also be by con- duction. This necessitates body contact with a cool floor, walls or water. One of the practical cooling devices for swine has been the wallow. This combines conductive losses to a cool liquid with evaporative cooling from the wetted surfaces (20). 2.4 Heat Loss by Radiation Radiation heat exchange is continuous between all objects. If they are of different temperature there is a net gain to the cooler object. Animals can dissipate heat by radiation to a cool surrounding. May be influenced by various structural and environmental control means (9). 2.5 Radiant Heat Load on an Animal The greatest source of radiation is the sun. An animal in the sun receives radiant energy from four sources: (a) direct beam solar energy from the sun, (b) diffuse sky radiation that has been scattered, reflected, and diffused out of the original beam, (c) atmospheric radiation emitted by particles or gases in the atmosphere, and (d) emitted and reflected energy from surrounding terrestrial objects (7). The radiant heat load on an animal in the sun as measured by black globe thermometer by Kelly, 22 El. (23) was found to be 244 BTU per hour square feet (of animal surface). The total radiation was subdivided into 121 BTU per hour square feet, for radiation from the sun and sky, 16 BTU per hour square feet for radiation from the horizon and 107 BTU per hour square feet for radiation from the hot ground. A shaded animal does not receive the direct solar beam; but is exposed to indirect solar radiation as diffused sky radiation and reflected and reradiated from the ground, shade and sur- rounding objects (9). 2.6 The use of a shade for environmental control The most economical means of environmental control for animals in tropical countries may be a shade. A simple shade can reduce the incoming radiation and consequently the radiant heat load on the animal. A reduction of from 30 to 50 percent of the total radiant heat load on an animal was found by Bond, 35 El. (7). In other work Bond, gt El. (2) found that the shade reduced the heat load from 244 BTU/hr (sq ft) of animal surface to 167 BTU/hr (sq ft). A Shade reduces the direct radiant heat load from the sun and the sky and substitutes shaded area for part of the hot ground, but it adds a new source of energy; the shade material itself. Kelly, gt a1. (23), measured thermal radiation from various sources surrounding a shaded animal they found in one example that 28 percent of the total radiant heat load came from the sky; 21 percent from the shade material; 18 percent from the sunny ground and 33 percent from shaded ground. 2.7 Orientation of Shade Usually shades in the United States are quite often oriented with the long axis North and South. Thus the moving shadow allows direct sun drying of the ground under the shade sometime during each day. In tropical regions the shades are more often oriented with the long axis East and West (8). Kelly, 32 a1. (23) studied the orientation of shades as an important factor which accounts for the amount of radiant heat load on the animals. They found that a shade with its long axis oriented East to West.will provide a cooler environment than one with a North-South orientation. Ground temperatures will be lower because the ground will be shaded for a greater part of the day. Another advantage of the East-West orientation is that a great portion of the shadow lies to the North of the shade, 10 providing possible exposure to the colder North sky. Kelly, et 31. (24) and Bond (8) have shown that the North area of a clear sky is generally cooler than other areas of the sky. 2.8 Shade Size Kelly, gt El. (23) studied the effect of shade size on the reduction of radiant heat load on animals. As the shade size increases there is more shaded ground as compared to hot ground, therefore the animal receives less radiation from the ground. However at the same time the portion clear sky for radiant cooling is smaller. In sum- mary the radiant heat load on animals is affected little by shade size. A later study by Kelly, gt_al. (26) pertained to the shade area requirement for beef feed lots. An increase in the average daily gain was observed when yearling steers were provided 48 square feet of shade per head as compared with 27 square feet per head. 2.9 Shade Height Shade height was studied by Kelly, §E_al. (23), they found that the radiant heat load on animals under high shades was less than under low ones. R. L. Givens (15) tested three different heights of artificial shades for cattle in the southeast (formerly ll Tifton, Georgia). Three shades 12 by 24 feet were erected at heights of 6, 9 and 12 feet and each covered with gal- vanized metal. He concluded that radiant heat load on animals in the southeast was greater under high shades than under low ones. The 12 foot high shade gave a value of 189.7 BTU/hr (sq ft) for radiant heat load at 12:00 noon and the radiant heat load under the 6 feet high shade was 175.1 BTU/hr (Sq ft) at the same time. There was evidently no thermal comfort for shades over six feet high. Bond, EE.El' (7) studied the influence of shade height on the radiant heat load on the animal. They found that an animal receives more diffuse solar energy reflected from the shade material from a high shade than from a low one. An animal under the center of a low shade receives less total radiant energy from the surroundings than an animal under the center of a high shade, but the influence of shade height is reversed when an animal is at the center of the shadow of the shade. 2.10 Animal Location Under the Shade Shade height has been shown to be related to the location of animals under the shade. Also the height of the animal above ground effects the radiant heat load. Hogs or chicken being closer to the cool shadow and away from the hot underside of the shade material will receive less amount of radiant energy per unit body surface than taller animals like cattle (7). 12 Kelly, et 31. (23) further showed that radiant heat loads on chickens increased with height above the ground. 2.11 Shade Materials Kelly, 33 El: (23) showed that 21 percent of the total radiant heat load on an animal may come from the shade material. This varies with the temperature of the roofing material; thus, the cooler the material the less the heat will be radiated to the animal. Many studies have been conducted to test shade materials. Kelly, gt El. (22) used four different materials and tested effectiveness of reducing solar radiation. The four materials tested were: wood, hay, aluminum and galvanized iron. At 12:00 noon with an air temperature of 99°F, the energy measured under the hay shade was 181 BTU/hr (sq ft), 190 BTU/ hr (sq ft) under the aluminum shade, 193 BTU/hr (sq ft) under the galvanized iron shade and 223 BTU/hr (sq ft) under the wood slat shade. At the same time the in- coming solar radiation was 527 BTU per hour per square foot which means that the hay covered shade cut off 1.7 percent more the incoming solar energy than did the aluminum shade; 2.3 percent more than the galvanized iron and 8 percent more than the wood slat shade. The use of paint for altering the radiation char— acteristics of shade materials was studied by Bond, §E_§l. 13 (2). White paint has a high reflectivity value for short wave-length radiation (low absortivity) and high emissi- vity for long wave-length radiation. Black paint in con- trast has a low reflectivity and high absortivity (30). Several paint combinations of black and white were tested. White t0p surface painted aluminum sheets were up to 15°F cooler than unpainted aluminum sheets. And white painted galvanized iron sheets were as much as 50°F cooler than unpainted ones. They concluded that the b§§2_paint char- acteristics were white on the top and black on the bottom. Kelly, et 31. (25) continued studying different shade materials and tested fifty different materials that might be used for shades. These materials ranged progres- sively from hay through aluminum, galvanized steel, as? bestos cement sheets, plywood, several types of plastic and finally snow fence. As in previous studies hay was found to be one of the b§§E_materials for shade construc- tion, with respect to its thermal qualities. (In troPical conditions this material is not recommended because it is a wonderful shelter for all kinds of insects.) This was attributed mainly to its relatively high insulating value and its convective heat dissipation ability. Aluminum was found to be a good shade material and if painted white on the top and black on the bottom was improved considerably. Galvanized steel was found slightly less effective than aluminum. Painting the t0p white and the bottom black 14 increased its effectiveness markedly. Snow fence was found to be the least effective of all materials tested. Kelly, gt El- (25) and Bond, gt 31. (6) tested the effectiveness of 50 materials and rated the effectiveness value "E" as a ratio of the reduction in radiant heat load to that of standard embossed corrugated aluminum. The standard aluminum was assigned an "E" value of 1:00. A material with an "E" value greater than 1 was more effect— ive than aluminum in reducing the radiant heat load. A material with a lower value was less effective. 2.12 Types of Shade Different roof types were tested by Neubauer, 35 El. (28). Temperatures measurements were.made on sev- eral kinds of black and white roofs and panels exposed to the sun at various slopes and orientation. The effective cool sky exposure was to the North during the middle of the day but faced toward West or East in the morning and afternoon, reSpectively. The type of roof was not found to be as important as location and time of the day. A good shade should be well ventilated, sloped up and toward the North, be well insulated and colored white on t0p. Hahn, gt 21. (18) studied the surface temperature differences that exist between metal roofs exposed to solar radiation and wind. They found an uneven distribu- tion of temperatures over the surface of each plate and 15 differences in surface temperatures were caused primarily by wind. The results of this study point out the import— ance of identifying the location of temperatures of metal roofs or metal sheets exposed to solar radiation and wind, in order for such temperatures to be meaningful. 2.13 Effect of Surrounding Objects on an Animal's Radiant Heat Load Surrounding buildings and objects greatly effect the animal's environment. Radiant heat load on the animal can be reduced by a grass surround instead of bare ground, concrete or black-tOp (9). Ittner, 2E.§l. (21) made some measurements at Davis and found when air temperature was 31.8°C (89.2°F) the surface temperature of clover and the ground under it was near that of the air; while for bare ground the surface temperature was 60°C (140°F), for gravel 50.2°C (122.3°F), concrete 48.3°C (118.9°F) and black-top 49°C (120.2°F). Radiation from nearby buildings can add to the animal's radiant heat load, particularly if it is a reflective surface exposed to the sun. Bond, EE.E£° (4) found a radiation value of 844 Kcal/hr(m2) [311.43 BTU/hr(ft2)] from white painted gal- vanized steel building in the sun, and 499 Kcal/hr(m2) [184.13 BTU/hr(ft2)] from the shaded side of the building. Radiation from an unpainted galvanized steel building was 16 627 Kcal/hr(m2) [231.36 BTU/hr(ft2)] from the sunny side and 467 Kcal/hr(m2) [172.12 BTU/hr(ft2)] from the shaded side. The radiant heat load on the animals can be reduced to make a better environment and improve productivity. Buildings, as part of the animal's environment have an important role in livestock enterprises. In tropical countries animal shelters, particularly those for cattle, are built essentially as shades consisting of a roof and possibly two side walls. More elaborate buildings are necessary in some cases. In temperate climates insulating materials are used to minimize heat losses to the outside during cold weather. Insulation has not been used in tropical countries to minimize heat gain through the roof from the outside. Some insulating materials have however been tested and recommended for summer conditions (16). If the total amount of heat flow through the roof which may represent 21 percent of the total radiant heat load (23), can be reduced, a better environment for the farm animals will be provided for trOpical conditions. 3. FACILITIES AND EQUIPMENT 3.1 The Building The data were collected at the Beef Cattle Research Center at Michigan State University. The building is a single story, clear span barn, consisting of two sections; the East and the West. The data were collected in the East section which has its long axis oriented exactly East to West. The building is Open to the South and closed on the North by a mobil-type win- dow. The North side of the building was kept completely open as it normally is in hot weather. The building has a gable roof of aluminum. Figure 1 shows the South side of the East section of the building and Figure 2 shows the type of roof. The East section of the building where the study was conducted is 111 feet long and 30 feet wide. A floor plan of the cattle pen with location of Black globe thermometers is shown in Figure 3. 3.2 Eguipment Roof surface temperatures were measured with COpper-Constantan Thermocouples installed at the center of the roof. Location of thermocouples are shown in Figure 4 and Table l. 17 Figure 1. View from the south side of the east section building. Figure 2. Lateral view of the building, showing the roof type. l9 .omumooa mums mumumEoEHmsu whoam xomam muons mcmm mapumo mo swam Hoon mafia moon in— .m musmwm ucoum .cmmo ARV sues .nn m mpwmuso K ---‘_—-_———“——_—-- —- com mauumo so? .nm S was s .m n6 «sense 0 mcowumooH mnoam xqmam HOOHM 0&0HUGOO concrete feed bunks mmaam pooh i mawcmm_ msH_ [cmmo_ fies. in: apnea. Jp— —-—-—————— SuHOZ I||¢ 20 .cowumooa mumumfiofinmnu macaw MomHm cam mmamsoooenmsu nuHB cowuomm ummm mo soapomm mmouo .v musmflm mono com ...¢..q....\.d .. mmaam boom mpflm ammo BOUCHB 0H N moon ESCHESH¢ spHOZ III.+ 21 Table l. Thermocouple locations in test building. Thermocouple Location 1 Black-globe thermometer 6 feet high 2 Inside air temperature 3 Black-globe thermometer 10 feet high 4 Inside air temperature 5 Roof surface underside (south slope) 6 Roof surface underside (north slepe) 7 Roof surface top side (north slope) 8 Roof surface t0p side (south slope) 9 Black-globe thermometer outside 6 feet high 10 Outside air temperature 11 Black-globe thermometer 3 feet high 12 Inside air temperature 22 Black globe thermometers were used to measure the radiant heat load. In the test conducted during the sum- mer of 1970 two thermocouples were placed inside the building; at 6 feet and 10 feet high; one was placed out- side the building under the sun at 6 feet high. In the second test conducted in the summer of 1971 another Black globe thermometer 3 feet high was placed inside the building. Thermocouples were located two inches away from the Black globe to measure air temperature (3). Black globe thermometers were built from ping pong balls accord- ing to Pereira specifications (29). Figures 5 and 6 show Black globe thermometers and their location. Air velocity was measured with a hot wire anemom- eter in feet per minute. Radiation values were obtained from the Michigan State University Meteorlogical Station at South Farm, East Lansing, approximately one mile away from the building. A 12 point Brown-Honeywell recording potentiometer was used to record thermocouple output for the test period. Tests were conducted during September 1, 2, 4, 5, 9, 1970 and June 27, 28 and 30, 1971. Temperatures were measured during each day from 10:00 a.m. to 4:00 p.m. Data for 3 days of 1970 and 2 for 1971 were analyzed; the days chosen were the most repre- sentative of all; clear days with higher radiation measurements. 23 Location of black globe thermometers. Figure 5. 24 Figure 6. Black globe thermometers made from ping pong balls. 4. THEORETICAL ANALYSIS Heat flow through the roof was computed using two methods: one was the sol-air temperature approach and the second was based upon measured roof surface temperatures. 4.1 Sol-Air Temperature The sol-air temperature "te" is an equivalent outdoor air temperature which in the absence of all radia- tion exchanges gives the same rate of roof heat transfer that exists with the actual combination of incident solar radiation, radiant energy exchange with the sky and the outdoor surroundings and convective heat exchange with the outdoor air (1). The sol-air temperature as develOped by Mackey and Wright (27) is: I t6 = t0 + (a .E;; ) (4.1) where: te = sol-air temperature °F to = outside air temperature °F a = solar absortivity of the outside surface I = the intensity of solar radiation incident upon the outdoor surface in BTU per hour per square foot of surface 25 26 fco = convective film coefficient on the outside surface. It is the time rate of heat ex- change by radiation, conduction and convec- tion of a unit area of a surface with the surroundings, including air and other fluids BTU/hr (sq ft) (°F) (1) 4.2 Intensity of Solar Radiation "I" The intensity "I" of solar radiation incident upon the outdoor surface is (l): I = Idn x K (4.2) where: ;_ Idn = total incident radiation on a plane normal to the sun's ray or direct normal radiation [BTU/hr (sq ft)] K = cosine of the angle of incidence 0 4.3 Angle of Incidence 0 Angle of incidence 0 is the angle between the rays of the sun and a line perpendicular to the surface being considered (14)- When the roof surface is horizontal the angle of incidence is: (D II 90 - B where: solar altitude a) ll 27 When the roof is sloped, the value of the angle of incidence 0 is a function of the roof slope. For gable type roofs the angle of incidence will have two values; one for each slope and as affected by the orientation of the buildings (Figure 7). In this study, the building has its long axis oriented East and West thus the angle of incidence 0 is: For the South facing slope: e = 90° - r° - B (4-3) m‘ For the North facing slope: 0 = 90 + r - B (4.3a) where: r = angle of roof's slope (see Figure 8) B = solar altitude 4.4 Solar Altitude B The altitude angle 8 is the angle in a vertical plane between the sun's rays and the projection of the sun's rays on the horizontal plane (30). Solar altitude B can be computed for any location in the northern hemisphere from the equation (30): sin 8 = cos L x cos 6 x cos H + sin L x sin 6 28 Figure 7. Sun angles on the roof planes of a gable-type building oriented East-West (Esmay, 1969). if Tan r = 0.333, r = 18° 26' Figure 8. Angle of the roof "r" with the horizontal. where: The seasonal location and is a function of time of the year (season) (30). The 29 North latitude of location (degrees) seasonal declination of sun (degrees) hour angle (equal 15° times number of hours from solar noon; positive from 12 noon to 12 midnight) (degrees) declination of sun "5" is independent of we: 4.5 Direct Normal Radiation "Ian" direct normal radiation is the total incident radiation on a plane normal to the sun's ray [BTU/hr (sq ft)] and is: Idn where: Ih = B = Once rate of heat the equation Q: = . (4.5) incident solar radiation on a horizontal surface [BTU/hr (sq ft)] solar altitude (degrees) 4.6 Heat Flow Through the Roof Q the sol-air temperature has been computed the flow through the roof can be computed from (14): U (te - ti) 30 where: Q = heat flow through the roof [BTU/hr (sq ft)] U = overall coefficient of heat transmission or thermal transmittance [BTU/hr (sq ft) (°F)] t = sol-air temperature °F t. = inside air temperature °F 1F1 4.7 Rate of Heat Flow to the Inside "qi" If inside surface's roof temperature is known the rate of heat transfer qi to the inside is: qi = fci (tsi ‘ ti) where: qi = rate of heat flow to the inside building from the roof [BTU/hr (sq ft)] fCi = inside film or surface conductance. It is the time rate of heat exchange by radiation, conduction and convection of a unit area of a surface with the surroundings, including air and other fluids BTU/hr (sq ft)(°F) tSi = temperature of the inside surface t. = inside air temperature 4.8 Mean Radiant Temperature The mean radiant temperature MRT of an environment is the temperature of a uniform black enclosure with which an object would exchange the same amount of energy as in the actual environment (3). 31 In the case of a mean radiant temperature determi- nation with the globe thermometer, the globe is the object and the MRT so determined will be true only for the globe (3). 4.9 Radiant Heat Load: "RHL" The radiant heat load "RHL" (3) is the total radiation received by an object from all of the surrounding space. It is the spherical, or whole-space, irradiation of the object; it includes only the incoming radiation at the object. The black globe thermometer has been made from copper spheres and used successfully to indicate the ther- mal radiant heat load at a point represented by the globe (3). Black-globe thermometers made from a ping pong ball can also be used (Pereira, gt_gl., 1967) (29). The radiant heat load calculation for the ping pong ball globe can be determined from equations: RHL = 0.232 /5 (t9 - ta) + 5 T94 English units RHL = 1.85 x 10-4 /5 (t9 - ta) + 6 T4 Metric units where: RHL = BTU/hr (sq ft) or watts/ sq cm t9 = temperature of globe, °F or °C ta = temperature of air, °F or °C ii- 32 air velocity, fpm or cm per second Stefan-Boltzman constant 0.173 x 10’8 12 BTU/hr (sq ft) (°R) or 5.67 x 10- watts/sq. cm. (°K) t + 460 degrees R or t + 273 degrees K 5. RESULTS Numerous variables must be quantified in order to compute sol-air temperature. The variables are: "8" solar altitude, "Idn" direct normal radiation and "I," the incident solar radiation upon the surface. 5.1 Solar Altitude "B" Computation Solar altitude was computed from the equation: sin 8 = cox L x cos 6 x cos H + sin L x sin 6 (4.4) where: B = solar altitude (see Appendix) L = 42° 47' (latitude North) 6 = seasonal declination of sun (see Appendix) H = hour angle (see Appendix) 5.2 Computations of Direct Normal Radiation Direct normal radiation was computed from the equation: I I = J- (4.5) dn sinB 33 34 where: Ih incident solar radiation on a horizontal surface for September 1, 4 and 5 and for June 27 and 28 (Tables 2, 3, 4, 5 and 6) "8" - solar altitude is shown in the Appendix Computed values of "Idn" are shown in Table 7. 5.3 Computations of the angle of incidence 0 The angle of incidence was computed from the equa- tions: 8 = 90 - R - 8 (south side slope) (4.3) 0 = 90 + R - 8 (north side slope) (4.3a) where: B = solar altitude R = angle of roof slope = 18° 26' The value of R was computed by the equation: TanR=IiL—1 L and h value are indicated in Figure 8; values of the angle of incidence 0 for the south facing slope and K (cosine 0) are shown in Table 35 in the appendix. Values of the angle of incidence O for the north facing slope and K (cosine O) are shown in the Appendix. 35 Table 2. Incident solar radiation on a horizontal surface "Ih" for September 1, 1970. Hour Grcal/cmzhr. Kcal/mzhr. BTU/ftzhr. 10:00 61.8 618 228.04 11:00 70.5 705 260.14 12:00 79.3 793 292.61 1:00 80.5 805 297.04 2:00 74.9 749 276.38 3:00 62.9 629 232.10 4:00 47.1 471 173.79 Table 3. Incident solar radiation on a horizontal surface "Ih" for September 4, 1970. Hour Grcal/cmzhr. Kcal/mzhr. BTU/ftzhr. 10:00 54.7 547 201.84 11:00 71.4 714 263.46 12:00 73.0 730 - 269.37 1:00 73.6 736 271.58 2:00 65.9 659 243.17 3:00 49.6 496 183.02 4:00 30.4 304 112.17 36 Table 4. Incident solar radiation on a horizontal surface “Ih" for September 5, 1970. Hour Grcal/cmzhr. Kcal/mzhr. BTU/ftzhr. 10:00 56.2 562 207.37 11:00 71.9 719 265.31 12:00 71.4 714 263.46 1:00 77.9 779 287.45 2:00 66.6 666 245.75 3:00 52.7 527 194.46 4:00 34.0 340 125.46 Table 5. Incident solar radiation on a horizontal surface "Ih" for June 27, 1971. Hour Grcal/cmzhr. Kcal/mzhr. BTU/ftzhr. 10:00 66.7 667 246.12 11:00 75.3 753 277.85 12:00 78.7 787 290.40 1:00 78.0 780 287.82 2:00 79.5 795 293.35 3:00 71.5 715 263.83 4:00 58.3 583 215.12 37 Table 6. Incident solar radiation on a horizontal surface "Ih" for June 28, 1971. Hour Grcal/cmzhr. Kcal/mzhr. BTU/ftzhr. 10:00 65.9 659 243.17 11:00 73.6 736 271.58 12:00 79.8 798 294.46 '3'“ 1:00 ’81.0 810 298.89 2:00 78.2 782 288.55 3:00 71.3 713 263.09 4:00 58.0 580 214.02 Table 7. Direct solar radiation on a plane normal to the sun's ray (BTU/ftzhr.) Idn’ 1970 Hour Sept. 1 Sept. 4 Sept. 5 June 27 June 28 10:00 316.1 284.42 293.82 289.58 286.33 11:00 327.61 336.68 340.72 302.85 296.21 12:00 357.36 333.66 327.88 308.77 313.29 1:00 373.62 347.06 369.15 313.72 326.00 2:00 383.12 342.66 348.20 345.15 339.77 3:00 383.12 308.22 329.68 355.33 354.69 4:00 381.78 253.32 285.96 357.05 355.73 38 5.4 Computation of the Intensity of Solar Radiation I The intensity of solar radiation incident upon the outdoor surface "I" was computed from the equation: I = I x K (4.2) dn where: Idn direct normal radiation [BTU/hr (sq ft)] (values are shown in Table 7) K cosine 0 (degrees) (see Appendix) There are two values of the intensity of solar radiation "I," one for the south facing roof shown in Table 8 and another for the north facing roof shown in Table 9. 5.5 Computation of the Sol-Air W Temperature ta The sol-air temperature was computed from the equation: te = to + (EL) (4.1) co where: te = sol-air temperature to = outside air temperature °F (measured values are shown in Table 10) a = 0.32 (value for aluminum (14). I = values for South and North side roof are shown in Tables 8 and 9 f = 4 BTU/hr (sq ft)(°F) 39 Table 8. Intensity of solar radiation "I" incident upon the outdoor surface (direct, diffuse and reflected) BTU/hr-ft2 south slope. 1970 Hour Sept. 1 Sept. Sept. June 27 June 28 10:00 285.54 164.15 262.52 281.73 278.49 11:00 309.76 316.24 319.38 301.71 295.03 12:00 342.46 317.80 311.65 308.67 313.17 1:00 353.26 325.98 346.03 312.54 324.70 2:00 337.50 306.92 311.11 335.79 330.47 3:00 316.55 252.01 268.67 325.57 324.81 4:00 272.30 178.23 200.31 294.19 292.87 Table 9. Intensity of solar radiation "I" incident upon the outdoor surface (direct, diffuse and reflected) BTU/hr ft2 north slope. 1970 Hour Sept. 1 Sept. Sept. June 27 June 28 10:00 147.10 128.09 130.87 185.23 182.89 11:00 183.82 183.69 184.07 225.65 220.24 12:00 212.73 193.28 188.21 242.31 245.52 1:00 209.64 189.35 199.42 233.74 242.39 2:00 178.28 154.32 155.09 220.77 217.03 3:00 123.78 95.15 100.32 175.06 174.38 4:00 57.30 34.59 37.82 113.98 113.16 40 Table 10. Outside air temperature "to" (degrees F). 1970 1971 Hour Sept. 1 Sept. 7 Sept. 7 June 27 June 28 10:00 74 78 78 89 91 11:00 79 85 87 93 95 12:00 84 93 88 94 96 1:00 80 91 88 95 96 2:00 80 93 87 95 97 3:00 78 93 88 97 96 4:00 75 93 90 96 98 Sol-air temperature values were computed for the following days: September 1, 4 and 5; and for June 27 and 28 for every hour from 10:00 a.m. to 4:00 p.m. Values are shown in Tables 11 and 12 for South and North slopes, 5.6 Computation of the Heat Flow Through the Roof "Q" The rate of heat flow through the roof was computed for both sides of the roof from the equation: Q = U (te - ti) (4.6) 41 Table 11. Sol-air temperature "t " degrees F, for the south slope. e 1970 1971 Hour Sept. 1 Sept. 4 Sept. 5 June 27 June 28 10:00 96.84 91.13 99.00 111.53 113.27 11:00 103.78 110.29 112.55 117.13 118.60 12:00 111.39 118.42 112.93 118.69 121.05 1:00 108.26 117.07 115.68 120.00 121.97 2:00 107.00 117.55 111.88 121.86 123.43 3:00 “103.32 113.16 109.49 123.04 121.98 4:00 96.87 107.25 106.02 119.53 121.90 Table 12. Sol-air temperature "te" degrees F, for the north slope. 1970 1971 Hour Sept. 1 Sept. 4 Sept. 5 June 27 June 28 10:00 85.76 88.24 88.46 103.81 105.63 11:00 93.70 99.69 101.72 111.05 112.61 12:00 101.01 108.46 103.05 112.38 115.64 1:00 96.77 106.14 103.95 113.69 115.39 2:00 94.26 105.34 99.46 112.66 114.36 3:00 89.90 100.61 96.02 111.00 109.95 4:00 79.58 95.76 93.02 105.11 107.05 42 where: Q = heat flow through the roof [BTU/hr (sq ft)] U = 0.923 BTU/hr (sq ft)(°F) te = sol-air temperature (°F) values are shown in Tables 11 and 12 t. = inside air temperature (°F) (measured values are shown in Table 13) Values for "Q" the rate of heat flow through the roof was computed for both sides, south and north and for the fol- lowing days of September: 1, 4 and 5 and June 27 and 28 for every hour from 10:00 a.m. to 4:00 p.m. Values are shown in Tables 14 and 15. Table 13. Inside air temperature "ti" (degrees F). 1970 1971 Hour Sept. 1 Sept. 4 Sept. 5 June 27 June 28 10:00 69 74 76 87 89 11:00 74 85 82 91 92 12:00 79 89 83 91 93 1:00 77 90 83 93 94 2:00 78 90 84 93 95 3:00 77 90 85 95 96 4:00 74 89 88 95 96 43 Table 14. Rate of heat flow through the south roof "Q" (BTU/hr ft2) 1970 1971 Hour Sept. 1 Sept. 4 Sept. 5 June 27 June 28 10:00 25.69 15.81 22.22 22.64 22.40 11:00 27.48 23.34 28.19 24.11 24.55 12:00 29.89 27.15 27.62 25.55 25.89 1:00 28.85 24.98 30.16 24.92 25.81 2:00 26.76 25.42 25.73 26.63 26.24 3:00 24.29 21.37 22.60 25.88 23.97 4:00 21.08 16.84 16.63 22.64 23.90 Table Rate of heat flow through the north side roof "Q" (BTU/hr ft?) 1970 Hour Sept. Sept. Sept. June 27 June 28 10:00 15.46 13.60 15.51 16.63 11:00 18.18 13.65 18.20 18.50 19.02 12:00 22.01 17.96 18.50 19.73 20.89 1:00 18.24 14.89 19.33 19.09 19.74 2:00 15.00 14.15 14.25 18.14 17.86 3:00 11.90 9.79 10.17 14.76 12.87 4:00 5.15 6.23 4.63 9.33 10.19 44 5.7 Rate of Heat Flow to the Inside qi The rate of heat flow to the inside through the roof can also be computed by the equation: q1 = fci (t . - t.) (4.7) SJ. »1 if the surface temperature of the underside of the roof is known. where: qi = ci = t . = 51 t. = 1 Values for "qi roofs and for rate of heat flow [BTU/hr (Sq ft)] -1.2 BTU/hr (sq ft)(°F) temperature of the inside roof's surface °F (measured values are shown in Tables 16 and 17) inside air temperature °F (values are shown in Table 13) " were computed for south and north facing the following days of September: 1, 4 and 5 and June 27 and 28; for every hour from 10:00 a.m. to 4:00 p.m. Values are shown in Tables 18 and 19. 5.8 Computation of the Radiant Heat Load iiRHL" The radiant heat load was computed from black- blobe thermometers readings,-under the sun and inside the building from the equation: RHL = 0.232 /5 (t - t ) + T 4'0 (4.9) 9 a 9 —s‘ . mm 1.4::- 45 Table 16. Temperature of the inside roof's surface °F (south). 1970 1971 Hour Sept. 1 Sept. 4 Sept. 5 June 27 June 28 10:00 90 87 94 106 108 11:00 96 104 105 111 115 12:00 104 112 106 112 116 1:00 101 111 108 114 116 2:00 100 110 106 115 120 3:00 97 108 104 116 118 4:00 92 103 101 112 114 Table 17. Temperature of the inside roof's surface °F (north). 1970 1971 Hour Sept. 1 Sept. 4 Sept. 5 June 27 June 28 10:00 82 85 86 102 102 11:00 89 96 97 107 108 12:00 96 104 98 108 112 1:00 92 103 99 110 111 2:00 91 102 96 109 110 3:00 87 98 93 108 108 4:00 78 94 91 105 105 46 Table 18. Rate of heat flow to the inside "q." BTU/hr ft2 (south). 1 1970 1971 Hour Sept. 1 Sept. 4 Sept. 5 June 27 June 28 10:00 25.2 15.6 21.6 22.80 22.80 11:00 26.4 22.8 27.6 24.00 27.60 ' 12:00 30.0 27.6 27.8 25.20 27.60 1:00 28.8 25.2 30.0 25.20 26.40 2:00 26.4 24.0 26.4 26.40 30.00 3:00 24.0 21.6 22.8 25.20 26.40 E 4:00 21.6 16.8 15.6 20.40 21.60 Table 19. Rate of heat flow to the inside "qi" BTU/hr ft2 (north). 1970 1971 Hour Sept. 1 Sept. 4 Sept. 5 June 27 June 28 10:00 15.6 13.2 12.0 18.00 15.60 11:00 18.0 13.4 18.0 19.20 19.20 12:00 20.4 18.0 18.2 20.40 22.80 1:00 18.0 15.6 19.2 20.40 20.40 2:00 15.6 14.4 14.4 19.20 18.00 3:00 12.0 9.6 9.6 15.60 14.40 4:00 4.8 6.0 3.6 12.00 10.80 47 where: RHL = radiant heat load [BTU/hr (sq ft)] t = temperature of globe °F (values are shown in g Tables 20 and 21) ta = air temperature °F (inside and outside air temperatures are shown in Tables 10 and 13) v = air velocity (ftpm) (see Appendix) G = 0.173 x 10’8 [BTU/hr (sq ft)](°R) T = inside or outside black globe temperature in 9 degrees R; (tg + 460°) (see Appendix) Radiant heat load was computed for the following days in September: 1, 4 and 5 and June 27 and 28; for 12:00 noon and for outside and inside the building. The computed values for June 27 and 28 of 1971 includes RHL for a black-globe thermometer at 3 feet high. Computed values are shown in Table 22. h. 48 Table 20. Outside black globe temperature measurement °F. 1970 1971 Hour Sept. 1 Sept. 4 Sept. 5 June 27 June 28 10:00 81 82 85 97 103 11:00 85 92 94 98 105 12:00 98 98 99 102 106 1:00 89 97 96 105 103 2:00 90 101 96 101 105 3:00 86 102 97 107 104 4:00 82 104 97 102 104 Table 21. Inside black globe temperature measurement °F. 1970 1971 Sept. 1 Sept. 4 Sept. 5 June 27 June 28 Hour 6 ft. 6 ft. 6 ft. 3 ft. 6 ft. 3 ft. 6 ft. 10:00 70 74 77 88 87 93 90 11:00 75 81 83 92 92 97 93 12:00 81 91 85 93 92 98 95 1:00 80 91 84 96 95 97 95 2:00 79 91 84 95 95 99 98 3:00 78 92 86 97 96 99 97 4:00 75 92 88 96 95 98 96 Table 22. 49 Radiant heat load at 12:00 noon BTU/hr (sq ft) —... . Inside Outside Day 3 feet high 6 feet high feet high Sept. 1 - 155.01 228.44 Sept. 4 - 166.42 185.11 Sept. 5 - 159.95 209.26 June 27 168.34 164.28 201.92 June 28 179.31 170.70 210.34 Note: Values for the black-globe thermometer at 10 feet high are the same as the values for 6 feet high. 6. USE OF INSULATION The term insulation refers to materials which have a high resistance to heat flow (10). Some building mater- ials, such as wood, have good insulating properties, while others like concrete are poor insulators. Insulation materials as well as other building materials are rated according to their ability either to conduct or to resist the flow of heat (10). This rating can be used to compare the effectiveness of the materials and determine the amount of insulation needed. The property that expresses the ability of a ma- terial to conduct heat is termed the thermal conductivity, "k" (30). This "k" value gives the amount of heat (BTU/hr) that will pass through a piece of material one inch thick and one square foot in area, when the temperature difference between the two surfaces is one degree Fahrenheit (30). The second method of rating materials is based on their ability to resist the flow of heat. Therefore, the thermal resistivity "R" of a material is a measure of that material's ability to resist the flow of heat (14). Nu- merically this is the reciprocal of the heat transmission value. 50 _£_T~__.r ‘ 51 Both the thermal conductivity and the thermal resistivity of a given material are related properties; and if one is known the other can be found by using the follow- ing equation: Insulating materials are therefore used to prevent loss of heat in farm buildings during the cold season. In this study the idea of using insulation to prevent the heat flow from the outside to the inside during hot weather is considered. For the computation of the decrease in heat flow through the roof, the following "R" values were chosen: R = 2, 4, 6, 8, 10 [inch/BTU/hr(sq.ft.)(°F)] 6.1 Computation of Decrease in the Rate of Heat Trangfer Through the Roofiby Using Insulating_Materials Decrease in the rate of heat transfer was computed by the general heat transfer equation: Qt = U x At (6.1) where: Qt = overall heat flow U = overall coefficient of heat transmission At = temperature difference 52 The overall coefficient of heat transmission U is: _ 1 U'R where: R = the overall resistance to heat transmission or insulation. The following values for R were used in the compu- tations: R = 2, 4, 6, 8 and 10. If we substitute in equation (6.1) U by %- equation (6.1) is: _ At (6.1a) Values of the rate of heat transfer were computed by using equation (6.1a) and for values of R = 2, 4, 6, 8 and 10. To compare the decrease in the rate of heat flow, the highest values already computed were taken from Table 14, one value for every day (the highest) from September 1, 4 and 5 and June 27 and 28. Decrease in the rate of heat flow is expressed in percentage. Table 23 shows values of Q already computed and values for Qt for the same days and for different values of R. 53 mH.mm em.m m¢.mm mm.m mm.am mh.v ma.mh oa.h mm.mv HN.¢H em.mm mm mesh ma.mm mm.m m¢.mm om.m mm.am om.v mm.mh H~.h ww.mv N¢.¢H mo.m~ hm mean ma.mm mm.m b¢.mm mo.v No.mm mv.m «a.mh ha.m mm.mv em.ma ma.om m .umom mH.mm vm.m mw.mm hm.m mo.mm mm.¢ mm.~b mm.> mm.mv Hh.vH ma.hm v .pmmm om.mm mm.m mv.mm do.w vo.mm hm.m «a.mh mo.m em.mv ma.mH mm.mm H .ummm w a oaum m a mum s a mum w a sum w a «um «um us when \osm mmflpHMb. sm: HON : 0: mmmncmoumm GA 30am pom: mo mmmmuomp can mum Hc\Dam =90: .mmmucmouwm ca 30Hm pawn mo mmmmnomc can mmsHm> sms usmnmmmeu now «ya ns\oem suos «mum ns\osm “so: 30am new: no mumm .mm manna 7. DISCUSSION OF THE RESULTS AND CONCLUSIONS 7.1 Heat Flow Thromgh the Roof "Q" and Rate of Heat Flow to the Inside "qiil ”in The rate of heat flow through the-roof "Q" was computed by using the sol-air temperature approach. The rate of heat flow to the inside was computed by using the surface temperature measurements for the purpose of check- ing the sol-air method. Both results have shown similar values (see Figures 9, 10, 11, 12 and 13). It means that the sol-air temperature approach can be used for analytical purposes of computing the rate of heat flow through the roof for Open livestock buildings, under summer conditions. The highest computed value for the rate of heat flow was 30.16 BTU/hr (sq ft) obtained at 1:00 p.m. on September 5 when air temperature was 83°F and through the south facing slope. The lowest computed value for the rate of heat flow was 4.63 BTU/hr (sq ft) obtained at 4:00 p.m. on September 5 and through the north facing slope. 7.2 Black-Globe Thermometer Readingg The globe-thermometer measurements were not sig- nificantly different for one at 6 feet high and the other 54 55 .onme .H nmnsdnddm now any who nsxsem ed nuance ms» on scan uses no mums can so. noon ms» smsonsn scan use: no mess .m mnemen amp mo Hsom oouv ooum ooum ooua .ooumH oouHH oouoa o d P U D. ea sw In. M mmoam T ed all. sued: m om s 0 oils m H / U. mmoam 1 90m . \I an .1111, cm .m T: G ow 56 .onme .e nmnsmndmm now and en. ns\sem ed defines may on 30H“ #60: mo much can :0: moon on» nmsouna 30am puma mo mumm man no Hsom cone ooum ooum ooua oouma oouHH oouoa o mmoam av ell. sumo: 0 Ollo mmoam 11[ cDSOm ow .oa mudmflm (a; bs) Jq/nmg sanIeA “Tb“ pus “On 57 .onda .m nonsdndmm non Ann dnc nsxsem ed deemed ms» on 36am news no mean can .0. noon ms» sedans» scan and: no mend .HH mnsmen man no snow cone doum ooum eons ooumfl cones dosed . o T (:1; bs) III/0:118 sanIPA II . bll pt're II on ow 58 .thfl .nm mean now And who ns\oam ed defines man on 30am 060: no menu can so: moon ms» canons» 30am ends mo mnnm .NH mnemem use no Hsom oouv comm ooum oouH ocuNH oouaa oouoa o .6 e u b. ca n th macaw u Samoa v A P T. a! L % cm s .n 8 .v I . V \ mm w. 0 ollo mmOHm x £50m om m, .b J H o¢ 59 .thH .mm mess now Ann 661 ns\sam ed defines mnu ou 30Hm pawn mo wumn can :0: Moon map cmsounu 30H“ Damn mo mumm .ma musmflm map mo nsom oouv ooum ooum ooua oouNH oouaa oonoa o 4M P u p. . 0H n macaw Lb sumo: u A P TI- m on 8 ad I mmoam H susom m 0.0II6 .I[ w” 1 om Mw .b .3 mm ov 60 at 10 feet high. The black-globe thermometer at 3 feet high showed higher temperature readings than the globes at 6 and 10 feet high. Differences in temperature read- ings were of one to five degrees. There were differences between the black-globe thermometer readings under the sun and inside as it was expected. Also the black-globe thermometers inside the building at 6 and 10 feet high did show temperature differences from one to three degrees in some cases from that of the air. The black-globe at 3 feet high showed temperature differences up to five degrees from that of the air. It means that the cooling effect of the wind influence more the black-globe at 6 and 10 feet than the black-globe at 3 feet high. 7.3 Radiant Heat Load The radiant heat load computed from black-globe thermometer readings at 12:00 noon outside and inside the building are shown in Figure 14. The highest value computed for radiant heat load was 228.44 BTU/hr (Sq ft) for September 1 under the sun when wind velocity was 350 feet per minute. The low- est RHL value under the sun was 185.11~BTU/hr (sq ft) for September 4 when wind velocity was 225 feet per minute. Direct normal radiation value at 12:00 noon for both days was: 357.36 BTU/hr (sq ft) for September 1 and 333.66 BTU/hr (sq ft) for September 4. 61 .smes 900m m was m um msfiwawsnnmnu mnamcw can can map Moons mumumaofinwsp mnonIxomHn How soon oouma um ADM vmv H£\Dam Umoa “no: ucmwomm .wa musmflm mm mssn nu mass m .nmmm sass a; m dsense I sons .nm e 039:.” D v .ummm H .ummm (4; b3) Iq/nia peer neeq nuerpsd can map Howss SEE; 62 The highest computed radiant heat load value for globes inside the building was 179.31 BTU/hr (sq ft) for the black-globe at 3 feet high and for June 28. The computed RHL value for the globe at 6 feet high was 170.70 BTU/hr (sq ft) for the same day at the same hour, 12:00 noon. It gives a difference of 8.61 BTU/hr (sq ft) between the two black-globes. This difference shows that the_RHL value in a point at 3 feet high (represented by the black-globe thermometer) is higher than one at 6 or 10 feet high. It was explained early that the globe- thermometer at 3 feet high is getting less cooling effect from the wind. The wind velocity for June 28 was 200 feet per minute at 6 feet high and 100 feet per minute at 3 feet high (both values were obtained near the globe). Also radiation from the shaded floor could account for the higher RHL value at 3 feet as compared at 6 feet high. Kelly, 32 31. (23) showed that 33 percent of the RHL on an animal came from the shaded ground. A reduction from 30 to 50 percent of the total radiant heat load on the animal is possible with a well designed shade (7). In the case of this study reductions of 10 percent to 32 percent in the RHL were found inside the building as compared under the sun. 63 7.4 Use of Insulation By using insulating materials with resistivity values from 2 to 10 (2, 4, 6, 8 and 10), decreases the rate of heat flow through the roof up to 89 percent. A decrease of 45 percent was found if an insulating material with a resistivity value of two is used. The higher the resistivity value of the material the lower the rate of heat flow through the roof. For example, if wood-fiber one inch thick is used (which has a resistivity value of R = 4 or U = 0.25 BTU/hr (sq ft)(°F) ) the reduction in the heat flow is 72 percent. In theory it would seem that insulating materials can be a solution for reduction of radiant energy through the roof for farm buildings. However more research in- this field is needed before recommends its use. 7.5 Roof Surface Temperature Roof surface temperature for the buildings were measured and the highest value was 120°F at 2:00 p.m. on June 28. Figure 15 shows measured surface temperature for June 28 as compared with air temperature. The highest surface temperature value was obtained on the South facing roof. 64 .snmesosz CH mm mesh How Am mmwummcv musumummsmu Ham can conunsm mvwmsH man no snow oouv ooum ooum ooua oouma oouaa oouoa . om and» \* [mummEmu \\\}\ om HHM k1111*\ Il' IIIII-IIIIII*\III 1T 1*: illllllum. mus» ooa [mummsmu cosmHSm macaw «00H cuuoc mcflmsfl . \\¥ ollllo OHH macaw nu50m ONH .ma sudden eanexedmem Jo 65 7.5 Conclusions The following conclusions may be made based upon this research: 1. The sol-air temperature approach can provide re- liable data on the additional heat load caused by solar radiation on exposed building roofs and Fe sidewalls. The similarity of results of the sol-air method and the calculation of heat transfer with measured roof surface temperature are highly dependent on the estimation of the surface film coefficient which varies considerably with air velocity. Both methods of solar radiation heat load calcula- tion accounted for the effect of the angle of the roof surface as related to the direct sun's rays. This varies with roof slope and orientation and the sun angle as effected by season, hour of day and location on the earth. A reduction in the radiant heat load up to 32 per- cent was found inside of the Open cattle barn as compared to outside in the direct sun. This was under Michigan conditions. A greater reduction would be expected under more intense radiation heat loads. 66 5. A practical amount of roof insulation showed a calculated reduction of heat transfer by 89 per- cent. The economic justification of this must be evaluated in specific locations based upon the actual reduction of heat stress on animals. IO. 8. COMPUTATION OF SOL-AIR TEMPERATURE AND HEAT FLOW THROUGH METAL ROOFS FOR OPEN FARM BUILDINGS IN TROPICAL CONDITIONS (VENEZUELA) Venezuela lies on the northern coast of South America, between the Tropic of Cancer and the Equator. It is bounded by latitudes 0° 45' and 12° 12' North, and longitudes 59° 45' and 73° 09' (32). Air temperature and solar radiation data were measured in Maracay, Aragua State, during the year of 1962. Maracay is located in a central region of the country at 9° latitude North. 8.1 Solar Altitude Computation Solar altitude was computed for 9° latitude North at 12:00 noon for one day each month corresponding with the seasonal declination days of Table 24 (14) Solar altitude was computed from the equation: B = 90° — (L - 6) (7-1) where: 'm II solar altitude (Table 24) 67 68 Table 24. Seasonal declination of sun "6" and solar altitude "8" degrees for 12:00 noon and 9° latitude North. Month Day "6" Degrees "8" Degrees January 21 -20.2 60.8 February 20 -11.2 69.8 March 21 0.0 81.0 April , 20 +11.2 92.2 May 21 +20.2 101.2 June 22 +23.45 104.4 July 23 +20.2 101.2 August 24 +11.2 92.2 September 23 0.0 81.0 October 23 —11.2 69.8 November 23 -20.2 60.8 December 22 +23.45 104.4 69 L = 9° latitude North 07 II seasonal declination of sun (Table 24) 8.2 Computation of the Angle of Incidence 0 The angle of incidence 0 for a 1/6 pitch gable- type roof with its long axis oriented east to west was computed from equations 4.3 and 4.3a. Values for the angle of incidence 0 and its cosine are shown in Table 25. 8.3 Com utation of the Intensity of Solar Radiation "I" The intensity of solar radiation "I" incident upon_ the outdoor surface was computed from equation 4.2 and is: I = Idn x K where: I = intensity of solar radiation BTU/hr (sq ft) Idn = direct normal radiation (values are shown in Table 26) BTU/hr (sq ft) K = cosine 0, cosine of the angle of incidence (values are shown in Table 25) Computed values of "I" are for 12:00 noon and for one day every month, are shown in Table 27 (31). 70 Table 25. Angle of incidence of sun-0 for the South and North slope and (cosine 0) "K" values at 12:00 noon. North Month 0 K 0 K January 10.77 0.98240 47.63 0.67387 February 1.77 0.99952 38.63 0.78116 March -9.43 0.98648 27.43 0.88755 April -20.63 0.93585 16.23 0.96021 May -29.63 0.86921 7.23 0.99208 June -32.88 0.83978 3.98 0.99758 July -29.63 0.86921 7.23 0.99208 August -20.63 0.93585 16.23 0.96021 September -9.43 0.98648 27.43 0.88755 October 1.77 0.99952 38.63 0.78116 November 10.77 0.98240 47.63 0.67387 December -32.88 0.83978 3.93 0.99758 71 Table 26. Direct solar radiation Idn at 12:00 noon. Month Kcal/mzhr Grcal/cmzhr BTU/ftEHF- January 1.280 128 472.3 February 1.390 139 513.0 March 1.380 138 510.6 April 1.450 145 536.5 May 1.180 118 436.6 June 1.200 120 444.0 July 1.240 124 458.8 August 1.340 134 495.8 September 1.450 145 536.5 October 1.300 130 481.0 November 1.220 122 451.4 December 1.290 129 477.3 72 Table 27. Intensity of solar radiation "I" incident upon the outdoor surface at 12:00 noon in BTU/hr (sq ft) Month "I" South SlOpe "I" North Slope January 463.79 318.33 February 512.48 401.16 March 503.96 452.90 April 501.62 515.04 May 379.4 433.10 June 372.96 442.66 July 398.69 455.12 August 464.06 475.96 September 529.52 475.87 October 480.51 376.14 November 443.27 304.24 December 400.93 475.86 73 8.4 Computation of the Sol-Air Temperature ft? The sol-air temperature was computed from equation 4.1 for aluminum roof, at 12:00 noon and for one day of every month, for both North and South slopes. Values are shown in Table 28 (Trujillo, 1970). 8.5 Computation of the Heat Flow Through the Roof [Q1 The heat flow through the roof "Q" was computed from equation 4.6, using the following values. U = 0.923 [BTU/hr (sq ft)(°F)] te = sol-air temperature-(Table 28) t1 = inside air temperature (Table 29) (monthly average) Values of the rate of heat flow through the roof "Q" are shown in Table 30, for 12:00 noon and for both South and North slopes. 8.6 Computation of the Inside Roof Surface Temperature Knowing the rate of heat flow and comparing equa- tions (4.6) and (4.7) assuming Q = q1 equations (4.6) and (4.7) can be equal, then giving: 74 Table 28. Sol-air temperature "te" at 12:00 noon °F. Month "te" South SlOpe "te" North Slope January 121 109 February 124 115 March 125 121 April 125 126 May 113 118 June 111 117 July 114 118 August 118 119 September 125 121 October 121 113 November 119 108 December 115 121 75 Table 29. Inside air temperature "ti" °F and °C at 12:00 noon . Month "ti" °F "ti" °C January 84 29 February 83 28 March 85 29 April 85 29 May 83 28 ‘ June 82' 28 July 82 28 August 82 27 September 83 28 October 83 28 November 84 29 December 83 28 Note: temperatures are average monthly during the day. 76 Table 30. Heat flow through the roof "Q" BTU/hr (sq ft) at 12:00 noon. Month "Q" South Slope "Q" North Slope January 34.59 23.74 February 38.22 29.92 March 37.58 33.78 April 37.41 38.41 May 28.29 32.30 June 27.81 33.01~ July 29.73 33.94 August 34.61 35.50 September 39.49 35.49 October 35.83 28.05 November 33.06 22.69 December 29.90 35.49 77 U(te-t.)=f. (t.-t.) 1 c1 31 1 then _ Ux te + ti (fCi - U) ci if the following values are known: U 0.923 f 1.2 ci equation (8.6) converts to: 0.923 t + t. 0.27 e 3. tsi = 1.2 (8'65” then if the sol-air temperature and the inside temperature are known, the inside surface temperature could be known. Computed values of the inside surface temperature are shown in Table 31. 8.7 Discussion of the Results The heat flow through metal roofs for Venezuela was higher than for Michigan as the radiation intensity was greater. Rate of heat flow values of 39.49 BTU/hr (sq ft) were computed for September on the South slope and 38.41 BTU/hr (sq ft) for April on the North slope. Heat transfer through both slopes had not big differences as the values obtained for Michigan. It can be explained; first of all because of the location of both 78 Table 31. Inside surface temperature "tsi" °F at 12:00 noon. Month "tsi" South Slope "tsi" North SlOpe January 112 103 February 115 108 March 116 113 April 116 117 May 107 110 June 105 109 July 107 110 August 110 111 September 116 113 October 113 106 November 111 102 December 108 113 79 tests; one at 9° latitude North and the other at 42° 47' latitude North. At lower latitude sun's rays are more perpendicular than-at higher latitudes. Seasonal decli- nation is another factor that influences in the sun ray's incidence. The highest projected roof surface temperature value was 116°F at 12:00 for April. This value is 4 ffi degrees lower than that for roof surface temperature in E Michigan (120° in one case). It is understandable because computation for Venezuela were made based upon average E radiation values and average air temperature values. A; Figure 16 shows roof surface temperature for a year in Venezuela as compared with air temperature. 80 .Amadsnmcm>v mGOHuHUcoo HMOHQOH» cw space m no man momsm>m as How soon oouma um mnsumummfimu Ham mcwmcfi can Moon 05“ mo mnsumummswu command mowmcH, .mH mnsmflm >02 poo. ummm mad Mann cash was flawed H82 :0 fl,,s..-\s--.r.ta..---r s sir n-7,... om Tm m d 3 m OOH m. 1 8 \ 1 n‘ o: ‘ . . ‘ - - omH macaw cunoc I . musumnmmfimu Ham madman." [III I macaw susom olno mnsumummsmu mOMMHSm moon moans.“ 9 . RECOMMENDAT IONS Some recommendations for the roof construction of livestock open sided buildings in Venezuela can be sug- gested: Use roofing material with high reflectivity and low absortivity value. One of the most suitable materials for livestock buildings in Venezuela is aluminum. Air velocity has shown to be of a great importance I in the amount of radiant heat load on the animal; there- fore, building should be constructed in unobstructed wind path or on a hill. General recommendations based upon experimental findings of many authors can be suggested: Use of showers to wet the animals (22) Lower temperature of surroundings by using trees, grass, etc. (9) Paint the roof white on top and black on bottom (6) and buildings white (4) Shades should be high (7) and its long axis oriented east to west (23). 81 REFERENCES REFERENCES American-Society of Heating, Refrigerating and Air Conditioning Engineers. ASHRAE Guide and Data Book. New York: ASHRAE, 1965. Bond, T. E.; Kelly, C. F. and Ittner, N. R. "Radia- r tion Studies of Painted Shade Materials." A ri- ' cultural Engineering, Vol. 35, No. 6 (June, 95 ), 389-92. Bond, T. E. and Kelly, C. F. "The Globe Thermometer 5 in Agricultural Research." A ricultural En ineer- ; ing, Vol. 36, No. 4 (April, 1355), 251-55, 360. 3 Bond, T. E.; Kelly, C. F. and Ittner, N. R. "White Paint for Farm Buildings." California Agriculture, 11, pp. 13-14, 1957. Bond, T. E. and Kelly, C. F. "Environment of Animals." The 1960 Yearbook of Agriculture, U.S. Government Printing Office, 1960. Bond, T. E.; Kelly, C. F.; Garrett, W. N. and Hahn, LeRoy.* "Evaluation of Materials for Livestock Shades, Applicable to Other Open Type Structures." California Agriculture, July, 1961, pp. 7-8. Bond, T. E.; Kelly, C. F.; Morrison, S. R. and Pereira, N. "Solar Atmospheric and Terrestrial Radiation Received by Shaded and Unshaded Animals." Paper presented at the 59th Annual meeting of the American Society of Agricultural Engineers, Amherst, Massachusetts, June 26-29, 1966. Bond, T. E. "Environmental Control in Tr0pica1 Countries." Paper presented at a Symposium on Environmental Control in Poultry Production, Edgmond, NeWport England, September 21, 1966. Bond, T. E.; Morrison, S. R. and Givens, R. L. "The Influence of Surroundings on the Radiant Heat Load of Animals." Paper presented at the 6lst meeting of the American Society of Agricultural Engineers, Logan, Utah, June 19-21, 1968. 82 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 83 Boyd, James. "Agricultural Structures." Class notes for the course A.E. 416, mimeograph, April, 1970. Burgos, Juan J. "Elementos del Balance Hidrologico y los Tipos de clima de Venezuela," gronomia Trop- Burgos, Juan J. "Regiones Bioclimaticas Para 1a Ganaderia en Venezuela." Agronomia Tropical, Vol. Dale, C. A. and Giese, H. "Effect of Roofing Mater- ials on Temperatures in Farm Buildings Under Summer Conditions." Agricultural Engineering, Vol. 34, No. 3 (March, 1953), 168-77. Esmay, Merle. Principles of Animal Environment. Westport: The AVI Publishing Co., 1969. Givens, R. L. "Height of Artificial Shades for Cattle in the Southeast." Paper presented at the Summer meeting of the American Society of Agricul- tural Engineers, Fort Collins, Colorado, June 22- 24, 1964. Griffin, J. G. "Field Studies of the Use of Insula- tion in Broiler Houses in Central Mississippi." U.S.D.A. ARS Bulletin No. 42-113, September, 1965. Hahn, LeRoy; Bond, T. E. and Kelly, C. F. "Use of Models in Thermal Studies of Livestock Housing." Transactions of ASAE, Vol. 4,-No. 1 (1961), 45-47. Hahn, LeRoy; Bond, T. E.; McKillop, A. A. and Kelly, C. F. "Relation of Air Temperature, Air Velocity, Solar Radiation and Roof Size to Metal Roof Temp- eratures." Transactions of the ASAE, Vol. 7, No. 3 (1964), 243—45. Hahn, LeRoy; Johnson, H. D.; Shanklin, M. and Kibler, H. H. "Inspired-Air Cooling for Lactating Dairy Cows in a Hot Environment." Paper presented at the Summer meeting of the American Society of Agricultural Engineers, Fort Collins, Colorado, June 22-24, 1964. Heitman, Hubert; Bond, T. E.; Kelly, C. F. and Hahn, LeRoy. "Effects of Modified Summer Environment on» Swine Performance." Journal of Animal Science, Vol. 18, No. 4 (November, 1959), 1367-72. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 84 Ittner, N. R.; Bond, T. E. and Kelly, C. F. "Methods of Increasing Beef Production in Hot Climates." California Agricultural Experiment Station, Bul- letin-761, 1958. Kelly, C. F. and Ittner, N. R. "Artificial Shades for Livestock in Hot Climates." A ricultural Engineering, Vol. 29, No. 6 (June, I948), 239—42. Kelly, C. F.; Bond, T. E. and Ittner, N. R. "Thermal Design of Livestock Shades." A ricultural En i- neering, Vol. 31, No. 12 (December, I959), 65I-6. m Kelly, C. F.; Bond, T. E. and Ittner, N. R. "Cold , Spots in the Sky May Help Cool Livestock." A ri- cultural Engineering,‘Vol. 38 (October, 1957 , Kelly, C. F. and Bond, T. E. "Effectiveness of Arti- ficial Shade Materials." A ricultural En ineerin , Vol. 29, No. 12 (December, I958), 758-59, 764. ‘ Kelly, C. F.; Bond, T. E. and Garrett, W. N. "Shade Area Requirements for Beef Feed Lots in the Imper- ial Valley." California Agriculture (September, Mackey, C. O. and Wright, L. T. "Periodic Heat Flow through Homogeneous Walls or Roofs." Transactions of ASH&VE, Vol. 50 (1944), 293-312. Neubauer, L. W. and Cramer, R. D. "Shading Devices to Limit Solar Heat Gain but Increase Cold Sky Radiation." Paper presented at the Winter meeting of the American Society of Agricultural Engineers, New Orleans, Louisiana, December 8-11, 1964. Pereira, Napoleon; Bond,T. E. and Morrison, S. R. "Ping Pong Ball into Black Globe Thermometer." Agricultural Engineering (June, 1967), 341-345. Threlkeld, J. L. Thermal Environmentgl Engineering. Englewood Cliffs: Prentice Hall, Inc., 1962} Trujillo, I. "Heat Transmission Through Three Dif- ferent Roofing Materials." Term Report presented at the A.E. 354 course (Spring, 1970). 85 32. "Venezuela at a Glance." Venezuela Up to Date, Vol. XIII (Spring, 1970), Washington. 33. Wilson, W. 0.; Hart, S. A. and Wooard, A. E. "Mist Cooling Hens in Cages by Fogging." Poultry Science, 34:606-613. APPEND IX 86 Table 32. Seasonal declination of sun "6" (degrees). Month Day Declination Degree September 1 7° 45' _ September 4 6° 37' September 5 6° 15' June 27 22° 55' June 28 22° 49' Table 33. Hour angle "H" degrees. Hour Angle Degrees 10:00 150° 11:00 165° 12:00 0° 1:00 15° 2:00 30° 3:00 45° 4:00 60° 87 Table 34. Solar altitude "8" (degrees) for 42° 47' latitude North. 1970 1971 Hour Sept. 1 Sept. 4 Sept. 5 June 27 June 28 10:00 46° 10' 45° 12' 44° 53' 58° 12' 58° 08' 11:00 52° 34' 51° 30' 51° 08' 66° 36' 66° 28' 12:00 54° 58' 53° 50' 53° 28' 70° 08' 70° 02' 1:00 52° 34' 51° 30' 51° 08' 66° 36' 66° 28' 2:00 46° 10' 45° 12' 44° 53' 58° 12' 58° 12' 3:00 37° 17' 36° 25' 36° 09' 47° 57' 47° 53' 4:00 27° 04' 26° 17' 26° 02' 37° 03' 36° 59' 88 om>v>.o .hm omv msooh.o .mm and omnon.o .ha omv maoah.o .m¢ osv mmmab.o .om ave cons mmmom.o .mm 6mm mmvam.o .mm 6mm mmbam.o .mo 6mm ommmw.o .mm osm mmwmm.o .ha ovm ooum mmmmm.o .mm ohm ommmm.o .Hv 6mm Hummm.o .vm 6mm mmoom.o .md 6mm vmmom.o .wm 6mm ooum mommm.o .Nm cam mmhmm.o .mm com mmmmm.o .vo com Nvmwm.o .NN oma mmmdm.o .oo omH oona momvm.o .mm oma «momm.o .mo omH mwmmm.o .vw and mmmmm.o .mm owH Nmmmm.o .mm ova oouma mommm.o .Nm cam mmbmm.o .mm com mmmmm.o .vo com mvmvm.o .NN oma mmmvm.o .oo oma oouaa mmmwm.o .mm cum ommmm.o .Hw 6mm Hummm.o .sm com mmoom.o .mv 6mm vmmom.o .wm 6mm oouoa M Q M ® M G M G M G H503 m nonempmmm m Hmnamummm v Hwnfimummm N Honsmummm a nonempmmm .mmoam mcfiomM nudom map How a has m.sdm mo mocmcfiosfl mo mamsc .mm magma 89 Hmvoa.o .am 6mm mumma.o .vm 6mm mmmmH.o .mo omm ommda.o .hm cam HHomH.o .NN cam ooud mm¢m~.o .nm 6mm amwom.o .na 6N5 vumom.o .Ho one mamam.o .hm can mommm.o .mo can oonm mmmmv.o .om owe msmvs.o .mm 6mm mmomv.o .va 6mm mwomv.o .mm cam mmmmv.o .ma 6mm ooum momam.o .sv 6mm wmowm.o .ma ohm Homvm.o .mm 6mm Hmmmm.o .va 6mm «Hamm.o .mm 6mm oouH mvmmm.o .mm owm mownm.o .mm ovm mmmhm.o .mm ovm ommmm.o .Hm 6mm mmmmm.o .mm 6mm oouNH momam.o .vv 6mm smovm.o .ma ohm Hmmsm.o .mm com Hmmmm.o .sH com madmm.o .mm 6mm oouaa mmmmv.o .om new mvmv¢.o .mm omw mmomv.o .sa 6mm mvomw.o .mm 6mm mmmww.o .ma 6mm oouoa M a M G M G M G M e H503 m Hmnfimummm m HwnEmummm d HmnEmummm N Hmnfimummm H Hmnamummm .mmon mcflomw sunoz ms» Hem o.mmu n.25m mo mocmpflosfl mo mamas .mm magma 90 Table 37. Air velocity feet per minute at 12:00 noon. Inside Outside Day 3 ft. high 6 ft. high 10 ft. high 6 ft. high Sept. 1 - 350 350 350 Sept. 4 - 225 225 225 Sept. 5 - 250 250 250 June 27 200 250 250 250 June 28 100 200 200 200 Table 38. Black globe temperature measurements at 12:00 noon degrees R. Inside Outside Day 3 ft. high 6 ft. high 6 ft. high Sept. 1 - 541 558 Sept. 4 - 551 558 Sept. 5 - 545 559 June 27 553 552 562 June 28 558 555 566 “5 m0 “7 “o m1 “7 ”0 m3 IllllHllllllHI