Document vBR3RgXeMQy9J9MQMMgwY9q38

206 CHAPTER 15 circulating chilled water through spray type or finned-coil surface dehumidifiere. 4. In some restaurants it ia convenient to use storage systems involving the use of a smaller refrigeration plant in connection with ice accumulating coils submerged in an insulated tank of water. This arrangement is usually only worth considering in connection with restaurants having a high peak of short duration, particularly in a locality where the power demand rate is high. 6. Solid adsorption dehydration equipment, white usually more costly, produces superior results where latent heat loads are especially high This is particularly true of dance Boors, where it is difficult to maintain humidities below 60 percent with con ventional refrigerating equipment alone. Where cheap and abun dant well water of sufficiently low temperature is available for aftereooling, absorption or adsorption denumidifiers may often be economically applied. 6.' The oaor and smoke problem in many restaurant and kin dred applications can be mitigated either by ample ventilation or by odor absorption equipment. The economics of the latter may be quite favorable, since it permits selection of a smaller re- 1962 Guide And Data Book frigerating plant, and achieves a reduction in both summer and winter operating cost. It is also possible to utilise electrostatic smoke abatement to decrease outside make-up air with resultant economy. REFERENCE 1J. F. Schmidt: Atr conditioning system design for churches, theaters, end auditoriums (Air Conditioning, Heeding and Venti lating, VoL 57, January 1960, p. 87). BIBLIOGRAPHY W. O. GOboy: Putting theatre cooling on a practical K**TM {Motion Picture Herald, VoL 198, March 5, 1955, pp. 8-9). Jack F. Schmidt: How to air condition churches (Atr Con ditioning, Heating and Ventilating, VoL 53, March 1956, pp. 83-87.) Vero O. Knudsea: Acoustics in comfort and safety {Journal M Acoustical Society of America, Vo). 21, No. 1, July 1949). CHAPTER 16 SCHOOL AIR CONDITIONING Genera/ Consstferafrans, Criteria for Design, Design Considerations,' Preliminary Design, Mechanical Plant Design, Types of Ventilating Systems, Types of Heating and Coo/mg Systems, Automatic Control, Operation, Maintenance HE purpose of this chapter b to outline the factors af less than those for conventional arrangements and systems. T fecting the selection of heating, ventilating, and air- The need for cooling b discussed in the following section. conditioning systems for schools. The components of these With regard to ventilation, code requirements vary from systems are the same as used for other types of buildings. Their combination in school systems, in some cases, will be acceptance of natural ventilation, such as obtained by opening of windows, to a requirement .of mechanical supply the same as for other buildings, but may differ considerably of a specified quantity of air, which sometimes b as high in others in order to provide optimum conditions for effec tive school work and to comply with local regulations. as 30 cfm of outdoor air per occupant. The variations in quantity of outdoor air specified usually are due to the lack of a uniform understanding of the reason for ventilation. Re GENERAL CONSIDERATIONS search has established that ventilation air is required, not Some of the factors involved in providing proper heating and ventilating plants are often not recognized fully. They include indoor temperature levels required for best learning and instruction, ventilation, arrangements and periods of use of school plants, advantages of automatic control, and proper perspective of costs. Many designers and school administrators approach the problem of providing proper indoor conditions as one of heat ing, whereas analysis may show and experience confirms that cooling rather than heating, is required during periods of occupancy most of the year. Often administrators have re marked "Our problem is not heating. It b to get rid of heat." Temperatures become excessive, particularly in classrooms, because of tire heat gains from occupants, adequate lighting, and sun effects. The optimum environment for learning has not been es tablished by basic research, though such research b cur rently in progress. Numerous surveys have been made in commerce and industry and in government on the increase in efficiency; i.e., in the amount and quality of work ac complished; of office and factory workers when temperatures are held downward to comfortable limits. They show increases in efficiency of roughly 30 percent and reduction of absen teeism of 20 percent. Few surveys have been made on the effect of cooling in classrooms. Conclusions of a recent comprehensive statistical type of survey1 of 150 teachers in the middle and south middle region of the United States included the following: to replace oxygen for breathing, but to dilute body odors, which become intensified in densely occupied spaces. A dis cussion of air requirements will be found in Chapter 8 of the 1961 Guide And Data Book. Elementary schools of recent design are generally tinglestory buildings, often placed at considerable distance from each' other. Windows 7 ft or more in height and extending the full length of one or more classroom walls, often raise great problems in maintenance of an optimum indoor at mospheric environment and in prevention of eye strain. Secondary or high schools are more often two- and three* story structures but present problems only slightly less severe than grade schools. Separatum of school buildings results in increased cost of the mechanical systems. A further characteristic of school buildings b a wide variation in use and occupancy. Classrooms (the largest single group of occupancies), lecture rooms, assembly rooms, auditoriums, and other similar areas have uniformly dense occupancies. Gymnasiums, cafeterias, laboratories, shops, and similar functional spaces have lighter occupancies and also have different and varying ventilation and temperature requirements. Many schools indude multipurpose rooms serving as auditoriums, gymnasiums, and community centers. The normal periods of operation are five days per week for nine months per year, with complete shut down duringweek-ends and vacation periods. Systems for administration areas, gymnasiums, auditoriums, and multipurpose rooms, suitable for community activities, will often be operated at times when the systems for classrooms and other general educational areas may not be in operation. Automatic control of temperature and system equipment 3. Much more willingness to do more research, 38 percei 4.- Much' greater ability to concentrate. 85 percent. 5- Much more effective use of skills already learned percent. 6. Much more effective use of study time, 59 percent. From this and other like surveys, it seems clear and definite that substantial improvement in learning will result from air conditioning the classroom. The effect in providing a better society and an improved economy in years to come follows with equal assurance. This b now generally recognized. As a b a necessity if comfortable conditions are to be obtained. Proper application of controls may return the cost of in vestment by savings in labor and fuel within a year or two. School boards are often criticized by their constituents for spending large sums of money for so-called luxury items, with the result that economy in construction and design becomes a paramount factor. This often tends to limit the mechani cal equipment selected below that required to maintain a proper indoor atmospheric environment. result, cooling or air conditioning was provided in more than 200 new U. S. schools by the close of 1959.1 Costs of schools ^respged for and provided with air conditioning have been CRITERIA FOR DESIGN Comfort, cleanliness, reduction of odore, maintenance of olertnesq, compliance with codes, installation cost, ease and cost of upkeep, cost of operation, and adaptability to con- 207