Document OoreqmL295jDGjMXoy4RRwjX

HEATING VENTILATINC AIR CONDITIONING GUIDE 1944 effective temperature for sedentary persons, as determined at the A.S.H.V.E. Research Laboratory, is 66 deg. As explained in Chapter 2 for so-called still air conditions, a relative humidity of approximately 50 per cent is required to produce an effective temperature of 66 deg when the dry-bulb temperature is 70 F. However, even where provision is made for artificial humidification, the relative humidity is seldom maintained higher than 40 per cent during the ex tremely cold weather, and where no provision is made for humidification, the relative humidity may be 20 per cent or less. Consequently, in using the figures listed in Table 1, consideration should be given to whether Table 1. Winter Inside Dry-Bulb Temperatures Usually Specified3 Type of Building Deg F Type of Building Deg F Schools-- Class rooms Assembly rooms____ __________ Gymnasiums.. Toilets and baths.____________ Wardrobe and locker rooms.-- Kitchens....... Dining and lunch rooms____ _ Plavrooms Natatoriums........ .............. 70-72 68-72 55-65 70 65-68 66 65-70 60-65 75 Hospitals-- . Private rooms Private rooms (surgical) ODerating rooms Wards. _ Kitchens and laundries Toilets . .. Bathrooms.___________ 70-72 70-80 70-95 68 66 68 70-80 Theaters-- Lounge rooms.......... -- 68-72 68-72 68 Hotels-- Dining rooms... Kitchens and laundries Toilets and service rooms 70 ' 70 66 65-68 68 Howes Stores......... 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 i `J,,hH ?Sre ChapterTM dl?"buIb temperature to be maintained depends on the relative humidity and hreC f ra conslder1 together constitute what is termed the effective temperate. provision is to be made for humidification, and if so, the actual relative humidity to be maintained. 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 1 so that the air temperature at the proper level will be used. By air temperature at tke 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 this fact should be made in calculating ceiling heat losses, particularly in the 128 CHAPTER 6. HEATING LOAD case of high ceilings. However, the exact allowance to be made may be somewhat difficult to determine as it depends on many factors, including (1) the type of heating system, (2) ceiling height and (3) the insideoutside temperature differential. The type of heating system is par ticularly important as the temperature gradient from floor to breathinglevel to ceiling may depend to a large extent on whether direct radiation, unit heaters or warm air is used, and in the latter case, whether the circu lation is by gravity, auxiliary fantor forced air. Although with properly adjusted air flow the temperature differential with unit heaters can be Table 2. Approximate Temperature Differentials Between Breathing Level and Ceiling, Applicable to Certain Types of Heating Systems Ceiling Height (Ft) 10 11 12 IS 14 15 16 17 18 10 20 25 30 35 40 45 50 60 3.0 3.6 4.2 4.8 5.4 6.0 6.1 6.2 6.3 6.4 .6.5 7.0 7.5 8.0 8J> 9.0 9.5 Breathing Level Temperature (5 ft Above Floor) 65 70 3.3 3.9 4.6 5.2 5.9 6.5 3.5 4.2 4.9 5.6 6.3 7.0 6.6 7.1' 6.7 7.2 6.8 7.3 6.9 . 7.4 7.0 7.5 7.5 8.0 8.5 9.0 9.5 10.0 8.0 8.5 9.0 9.5 10.0 10.5 72 3.6 4.3 5.0 5.8 6.5 7.2 7.3 7.4 7.5 7.6 7.7 8.2 8.7 9.2 9.7 10.2 10.7 74 3.7 4.4 5.2 5.9 6.7 7.4 7.5 7.6 7.7 7.8 7.9 8.4 8.9 9.4 9.9 10.4 10.9 76 3.8 4.6 5.3 6.1 6.8 7.6 7.7 7.8 7.9 8.0 8.1 8.6 9.1 9.6 10.1 10.6 11.1 78 80 3.9 4.0 4.7 4.8 5.5 5.6 6.2 6.4 7.0 7.2 7.8 8.0 7.9 8.1 8.0 8.2 8.1 8.3 8.2 8.4 8.3 . 8.5 8.8 9.3 9.8 10.3 10.8 11.3 9.0 9.5 10.0 10.5 11.0 11.5 85 90 4.3 4.5 5.1 5.4 6.0 6.3 6.8 ' 7.2 7.7 8.1 8.5 9.0 8.6 9.1 8.7 9.2 8.8 9.3 8.9 9.4 9.0 9.5 9.5 10.0 10.5 11.0 11.5 12.0 10.0 10.5 11.0 11.5 12.0 12.5 The figures in this table are based on an increase of 1 per cent per foot of height above the breathing level (5 ft) up to 15 ft and 1/10 of one degree for each foot above 15 ft. This table is generally applicable to forced air types of heating systems. For direct radiation or gravity warm air. increase values 50 per cent to 100 per cent. reduced to a minimum, it is also possible with improper adjustment that the temperature differential will be increased over that which would normally result without mechanical circulation of the air. Tests in the University of Illinois Research Residence1 indicated that the breathing level-ceiling temperature differential varied from about 1 to 3}4 deg for three types of warm air heating systems, namely, forced air, auxiliary fan and gravity. These tests were based on an outdoor air tem perature of approximately 20 F. Tests in the University of Wisconsin Field House2 having a ceiling height of.97 ft showed a temperature gradient of about % deg per foot for the first 15 ft of elevation and 1University of Illinois Engineering Experiment Station Bulletin No. 318--Investigation of Oil-Fired . Forced Air Furnace Systems in the Research Residence, by A. P. Kratz and S. Konzo. A-.S.H1V.E. Research Report No. 958--Temperature Gradient Observations in a Large Heated Space, by G.L. Larson, D. W. Nelson, and O. C. Cromer (A.S.H.V.E. Transactions, Vol. 39, 1933, p. 243). .j 129