Document J3zNmDL6R5z72xwJykLygezLZ

248 CHAPTER 11 1950 Guide H. E. Robinson (U. S. Department of Commerce, National Bureau of Standarde Building Materials and Structures Report BMS 103). Concrete Floors for Basementless Houses (University of Illinois, SmaUHomes Council Circular No F 4.3). Heat Requirement Tables for Intermittently Heated Buildings (Engineering Experiment Station Bulletin, No. 60, A. and M. College of Texas, College Station, Texas) contains a set of tables applicable to either intermittent heating or cooling. Further information may be found in a paper, A Method of Compiling Tables for Intermittent Heating, by Elmer G. Smith (A.S.H.V.E. Journal Section, Heating, Piping and Air Conditioning, June, 1942, p. 386). CHAPTER 12 COOLING LOAD Cooling Load Calculations; Design Conditions; Instantaneous Heat Load; Solar and Sky Radiation, and Heat Transmission Losses; Principles of Periodic Heat Flow; Practical Tables for Calculating Solar Heat Gain Through Walls and Roofs; Glass Areas and Design Tables; Load from Interior Partitions, Ceiling and Floors; Load from Outside Air, Ventilation and Infiltration; Ef fect of Outside Air on Load; Heat Sources Within Conditioned Space; Moisture Heat Load; Miscellaneous Heat Loads; Re quired Air Quantity Through Conditioning Equipment; Minimum Entering Air Temperature; Example Cooling Load Calculation THE variables affecting cooling-load calculations are numerous, often difficult to define precisely, and always intricately inter-related. Most of the components of the cooling load vary in magnitude over a wide range during a 24-hour period, and as the cyclic changes in load compohents are not usually in phase with each other, careful analysis is re quired to establish the resultant maximum cooling load for a building or zone. A zoned system must often handle peak loads in different zones at different hours. Economic considerations must be of particular influence in the selection of equipment for cooling season operation in comfort air conditioning and this fact, coupled with present inadequacies in available data and knowl edge of lie air-conditioning art, places a premium on the experienced judg ment essential to successful design or practice. Variations in the weather, building occupancy and other factors affecting load necessitate carefully coordinated controls to regulate simultaneously the components and the equipment to maintain the desired room conditions. The calculation procedures presented in this chapter deal with the vari ous instantaneous rates of heat gain, both sensible and latent, in a condi tioned space. There may be an appreciable difference between the net instantaneous rate of heat gain and the total cooling load at any instant. This difference is caused by the storage and subsequent release of heat by the structure and its contents. This thermal-storage effect may be quite im if: portant in determining an economical cooling equipment capacity. The lack of any adequate means of treating this storage quantitatively in its entirety for a complete structure, must be recognized in judging the pro cedures and data presented for calculating individual components of the net rate of instantaneous heat gain. Solar healing calculations involve the same principles as cooling load calculations. Many of the data on solar radiation given in this chapter are useful in calculations for solar heating. COOLING LOAD CALCULATIONS Summer cooling load calculations, whether for industrial or comfort applications, require consideration of the following factors: A. Design Conditions: (1) Indoor conditions. (2) Outdoor conditions. (3) Ventilation rate. B. Instantaneous Heat Load, Sensible and Latent: (1) Load from solar radiation, ' 249