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240 CHAPTER 11 1951 Guide 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 listed 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. F ig . 1. sotherms of Win t e r Outdoor D esig n T em peratureI Heating Load 241 In rooms having large glass areas, when sun is not shining, or in rooms with walls having a high transmission coefficient, the lowered surface tem perature will cause a feeling of coolness even though the air temperature in Sie room is at or above the temperatures indicated in the table. In rooms of this character, it is desirable to design for even higher temperatures than those listed, unless a compensating high temperature surface is installed to offset the low temperature surfaces. r'-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 such reductions in air, temperature are slight in operation. Table 2. Winter Inside Dry-Bulb Temperatures Usually Specified* Type of Building Deg F Type of Building Deg F Schools-- Assembly rooms-------------------Gymnasiums.-----------------------Toilets and baths..--..-----------Wardrobe and locker rooms.... Kitchens............... -................... Playrooms.................................. 70-72 68-72 55-65 70 65-68 66 65-70 60-65 75 Hospitals-- Private rooms.---------------------Private rooms (surgical)-------Operating rooms.--;----...... Kitchens and laundries___ __ Toilets............ ................. ........... Bathrooms.--............................. 70-72 70-80 70-95 68 66 68 70-80 Theaters-- Lounge rooms....... .. ................ Toilets........ --..................... ...... 68-72 68-72 68 Hotels-- Bedrooms and baths....... .......... Kitchens and laundries............ Toilets and service rooms........ 70 70 66 65-68 68 Homes.______________ ______ ____ Stores____ Public buildings. Warm air baths._____ ______ Steam baths...... -......................... Factories and machine shops.. Foundries and boiler shops.... Paint shops.___________________ 70-72 65-68 68-72 120 110 60-65 50-60 80 * The most comfortable dry-bulb temperature to be maintained depend* on the relative humidity and air motion. Theee three factors oonsidcffod together constitute what ie termed the elfeftM temperature. (See Chapter 6.)' When relative humidity ia not controlled aeparately, optimum dry-bulb temperature for comfort will be slightly higher than shown in Table 3. Temperature at Proper Level. 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 warmer or less dense air to rise. An allowance for thisJ fact should be made in calculating ceiling heat losses, particularly in the case of high ceilings. However, the exact allowance to be made may be somewhat difficult to determine as it depends on many factors, including