Document 823XoYLvJ7dqNQrXg2mJ76wLB

/240 CHAPTER 11 1952 Guide effective temperature for sedentary persons, as determined at the A.S.H.V.E. Research Laboratory, is 67-68 ET. As explained in Chapter 6 for so-called still air conditions, a relative humidity of approximately 50 percent is required to produce an effective temperature of 68 ET when the dry-bulb temperatime is 72.5 F. However, .even where provision is made for artificial humidification, the relative humidity is seldom maintained higher than 40 percent during the ex- HeatingLoad 241 tremely cold weather, and. where no provision is made for humidification, the relative humidity may. be 20 percent or less. Consequently, in using the figures fisted in Table .2,- consideration should be given to the actual relative humidity to be maintained, if provision is to be made for humidifi cation. If no humidification is to.be provided, the higher temperatures may not even produce comfort on cold days; if humidity is to be main tained at 50 percent, the. lower, temperatures will apply. In rooms having large: glass areas, when, sun is not shining, or in rooms with walls having a high transmission coefficient, the lowered surface term perature will cause a feeling of, coolness even though the air temperature in the room is at or above the temperatures indicated in the table. Ini rooms of this^character, it is desirable to design for even higher temperatures than those listed, unless a compensating higher temperature surface is installed. to offset the low temperature surfaces. Table 2.; Winter.Inside Dry-Bulb Temperatures Usually Specified* Type op Building. Deo F. Type op Building Deg.F Schools-- Assembly rooms............................................. Toilets and baths___..................... ............. Wardrobe and locker rooms........ 70-72 68-72 55-65 ` 70 65-68 1 65-70 Playrooms................... . .................;........... 60-65 . `75 ` Hospitals-- Theaters--' Hotels-- - Bedrooms and baths. ................................. ' Toilets' and service rooms................. ;.... Private rooms (surgical).............. .......... - ?0-80 Stores.......................................... ;.................. Operating rooms........ .......................... Public buildings...'...................... ........... . 70 66 68 70-73 65-68 68-72 66 ' 70-80 Steam baths.!;.!.................... ........................ - no Factories and machine shops........ ...... 60-65 Paint Shops. .. ............................. ............. - 80 * The most comfortable dry-bulb temperature to be maintained depends on the relative humidity and air motion. These three factors considered together constitute what is termed the effective temperature. (See Chapter 6.) - When relative humidity is not controlled separately, optimum'dry-bulb temperature for conifort <will be slightly higher than shown in Table 2. The inside temperatures specified in Table 2 may be used for panel heated spaces as well as for spaces heated by warm air, radiators or con vectors. It is true that warm panel surfaces tend to produce a comfortable environment at a lower room air temperature than when warm panels are not present, but field experience.in the United States.has.indicated that actual reductions in air temperature are slight in operation. Temperature at Proper Levei. In making the actual heat loss compu tations, however, for the various rooms in a building it is often necessary to modify the temperatures given in Table 2 so that the air temperature at the proper level will .be used. By air temperature at the proper level is meant, in the case of walls, the air temperature at the mean height be tween floor and ceiling; in the case of glass, the air temperature at-the mean height of the glass; in the case of roof or ceiling, the air temperature at the mean height of the roof or ceiling above the floor of the heated room; and in the case of floors, the air temperature at the floor level. Temperature at Ceiling. The air temperature at the ceiling is generally higher than at the breathing level due to. stratification of air resulting from the tendency of the.-warnier or:.less-dense air-to rise. Amallowance.for this fact should be made in calculating ceiling heat losses, particularly in the