Document JNBLkQQ2vvbD3NbDRGq1qZ5R6

324 CHAPTER 29 1962.Guide And Data Book economical to air condition poultry houses by any means other than spray mists or evaporative coolers. Summer protective measures for swine are primarily shades with wallows or a water sprinkler. Enclosed swine buildings generally utilixe ventilation or evaporative coolers. However, the rapid development of moderately priced refrigerating equipment, better knowledge of the benefits of producing swine at lower than normal summer building temperatures, and the increasing number and sixes of year-round production enterprises have intensified the use of an interest in me chanical air conditioning. The most commonly used system for cooling feeder pigs and breeding stock is high ventilation rate (50 to 100 cfm per animal) with thermostatically controlled water sprinkling systems** set to supply up to % gph per animal when building temperatures exceed 80-85 F. Evaporative coolers are quite common and effective in areas where the average summerwetbulb temperature is 70 F and below. Mechanical air condi tioning is used mostly in farrowing and nursery houses be cause sprinkling systems wet floors, an undesirable condition for newborn pigB. Odor control in swine buildings requires that some fresh air be admitted continuously, the ventilation rate being in fluenced by the frequency of waste removal. Table 3 gives ventilation rates for odor control based on observations of buildings which are cleaned once each day. Space conditioning with mechanical refrigeration equip ment is generally considered by most producers to be more expensive than the benefits warrant. Estimates of cooling loads indicate a range of 0.5 to 0.75 tons per sow and litter and 0.1 to 0.2 tons for each feeder pig. Room air conditioners have been used in farrowing stalls to prevent heat exhaustion when temperatures rise above 90 F. However, large quantities of feed dust and other foreign material commonly found made swine buildings rapidly clog air passages, and the ammonia, in the air may lead to corrosion of heat exchangers. Zone cooling systems which reduce refrigerating equipment size through oliminat-ing the need to cool the entire shelter have met with more widespread acceptance, particularly for farrowing houses. Two types of zone systems are in use. One type*9 uses insulated ductwork to pipe a hmII volume of chilled air at low velocity (100-300 fpm) to the snout of the sow. The primary objective is the reduction of the in spired air temperature and moisture content to improve respiratory heat dissipation. System capacities are on the order of 0.1 ton of refrigeration and 10 to 35 cfm of air per sow. The other type of zone cooling system uses a small, direc tional, high velocity, low volume blower fitted with a flexible tube for each sow, the blowers pulling cooled air from a common insulated duct. Although the sow is free to inhalt* tiie cooled air, the major cooling is accomplished by convec- tion from the skin of the animal No special effort is made to reduce the dewpoint temperature of the cooled air. Capacities ' per sow for this system are 0.1 ton of refrigeration and 70 to 80 cfm of air discharging from the nozzle at 2500 to 3000 fpm. Both zone systems are suitable for year around ventilation as heating equipment can be easily added to warm the cold ' intake air. Summer cooling of dairy bams, other than with fa-na, is not considered economical for most farms at the present time, Table 3 .... Recommended Summer Ventilation Rates for Odor Control in Swine Buildings Cleaned Oaily Size of Pig, (b VentMotion rate. cfm/onlaat 12-40 50-100 100-200 L&ct&ting Sow with litter g 12 15 40 less the economic situation justifies supplemental heat, the calculated ventilation rate will need be compromised accord ing to the heat available for warming the incoming air. The total moisture load (animal feces, urine, and equipment) should be considered. Figs. 5 through 13 show moisture loads that might be expected with various types of livestock and with various systems of management. Total heat refers to the sum of all sensible and latent heat released within a structure. Generally, the heat and moisture from equipment (lights, motors, and waterers--except for spillage) is of relatively Tittle consequence.. Summer Load calculations will need to consider not only the heat from livestock, litter fermentation, and equipment, but also the beat gain of the structure. However, air conditioning may not be needed during the entire day. Tests indicate that no production losses will be experienced with most farm live stock if thermal comfort conditions are exceeded for only part or a day and temperatures during the remainder of the day are sufficiently low to permit recovery. Insulation Insulation of livestock buildings aids in maintaining warmth and permits a greatercirculation of fresh air than pos sible in non-insulated animal shelters. With adequate in sulation and density of livestock within a shelter, animal heat generally will warm cold make-up air sufficiently to maintain conditions conducive to good production, without DESIGN FACTORS Load Calculations Load calculations for winter air conditioning systems should be based on the moisture that needs be removed. Un- Fig. 5 .... Stable Heat and Moisture Dissipation Rates with Stanchioned Dairy Cattle* Air Conditioning for Animals SHORTHORN CALVES JERSEY CALVES 325 AGE OF CALVES- WEEKS * Pens deooed daily. ACE OF CALVES - WEEKS Fig. 6____ Stable Heat and Moisture loads for Beef and Dairy Calves in Pens*'*14* adding supplemental heating. Although a portion of animal's feed intake is used for increased metabolism at cold tem peratures, the feed saving obtained by supplemental heating rarely pays for the expense of the system in animal shelters. The heat saved by use of insulation permits the removal of the animal's moisture output with ventilation. In addition, condensation on walls and ceilings is reduced in an insulated structure, thus increasing the life of the structure, contribut ing to cleaner barns (condensation quickly collects the dusts of bams), and reduces the possibility of feed deterioration. - The determination of the economic amount of insulation to be used in animal shelters is complicated by variability in response of animals to temperature, feed costs, weather condi tions, and the difficulty of isolating ambient air conditions as an independent parameter of production. To meet these de mands, engineering estimates must be based somewhat on judgment, and are, therefore, subject to adjustment accord ing to the experience of the design engineer. For further in formation on insulation, see Chapter 22 of the 1961 Guide Akd Data Book. Internal moisture load for animal shelters exceeds that en countered for human occupancy. In addition to vapor from body surfaces, vapor from body wastes add to the moisture problem. Thus, insulation miist have a higher degree of vapor barrier protection than used in offices or dwellings. A good vapor barrier and ventilation above the insulation are essential factors in making roof insulation effective. A treatise** on insulation of poultry laying houses led to the suggested resistivities shown in Table .4. (See fig. 14 for identification of zones.) Insulation values for miUctng rooms are shown in Table 5. The function and economy of insulation in reducing the peak afternoon hot weather temperatures has not been thoroughly investigated. For regions with high summer heat gain, the side walls are traditionally opened to permit free movement of breezes through the house. Some studies have shown that a well-insulated (U = 0.06 for the walls and ceiling) windowless houses with pad and fan evaporative cool ing can be controlled enough to give good poultry produc tion in the summer in some parts of the United States. The use of overhead insulation creates a lag in temperature peak between the inside and the outside, reduces roof temperature and consequent radiation to the animal, and reduces the con- * Pea* daorwd mqr Wednesday. Dafa vote 4 nontia oU beef eaivet. 7 .... Effect of Accumulated Litter on Stable Heat and Moisture Loads*41 SHEEP WEIGHT -- POUCS Fig. 8 .... Metabolic Heat Production of Sheep at Approximately 70 F**