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Heating Ventilating Air Conditioning Guide 1938 AIR MOVEMENT AND DISTRIBUTION Stagnant warm air, no matter how pure, is not stimulating and it detracts to some extent from'the quality of air. Experience, and recent field studies by the A.S.H.V.E. Research Laboratory45 place the desirable air movement between 15 and 25 fpm under ordinary room temperatures during the heating season. Objectionable drafts are likely to occur when the velocity of the air current is 40 fpm and the temperature of the air current 2 F or more below the customary winter room temperature. Higher velocities are not objectionable in the surnmer time when the air of Enclosure, and Dry-Bulb Temperature of Incoming Air temperature exceeds 80 F. Variations in air movement and temperature in different parts of occupied rooms are often indicative of relative air distribution. The work of the A.S.H.V.E. Research Laboratory indicates that an air movement between 15 and 25 fpm with a temperature variation of 3 F or less in different parts of a room, 36 in. above floor, insure satis factory distribution. Considerable evidence was obtained in these tests to show that measurements of carbon dioxide are not essential for the study of air distribution, or for indirect measurements of outdoor air ^Classroom Drafts in Relation to Entering Air Stream Temperature, by F. C. Houghten. H. H. Trimble, Carl Gutberlet and M. F. Lichtenfels (A.S.H.V.E. Transactions, Vol. 41, 1935, p. 268). 72 Chapter 3- Physical & Physiological Principles of Air Conditioning Table 4. Relation Between Metabolic Rate and Activity3 Hourlt Meta bolic Rate for Avo. Person or Total Heat Dissipated, Btu per Hour Hourly Sensible Heat Dissipated, Btu per Hour Hourly Latent Heat Dissipated, Btu per Hour Averts Person Sented 2t Rest Average Person Standing at Rest1 384 431 Tailor*............... ............. --------- Office Worker Moderately Active 482 490 Clerk, Moderately Active, Standing at Counter.--........ 600 Book Binder*.-------- ----- 626 Shoe Maker*; Clerk, Very Active Standing at Counter.--.......... 661 Pool Player............ ------................ 680 Walking 2 mph*. 4; Light Dancing.................................... Metal Worker*.............. ................ 761 862 Painter of Furniture*--------------- 876 Restaurant Serving; Very Busy.. 1000 Walking 3 mph*......................... . 1050 Walking 4 mph*. 4; Active Dancing, Roller Skating......... 1390 Stone Mason*:............................... 1490 Bowling.......................................... 1500 Man Sawing Wood*----------------- 1800 Slow Run4...................---------------- 2290 Walking 5 mph*.....--..............-- 2330 Very Severe Exercise5.................. 2560 Maximum Exertion Different People4........................................ 3000 to 4800 225 225 225 225 225 225 225 230 250 277 280 325 346 452 490 490 590 159 206 257 265 375 401 436 450 511 585 596 675 704 938 1000 1010 1210 Moisture Dissipated, per Hour Grains 1070 1390. 1740 1790 2530 2710 2940 3040 3450 3950 4020 4560 4750 6330 6750 6820 8170 Lb 0.153 0.199 0.248 0.256 0.362 0.387 0.420 0.434 0.493 0.564 0.575 0.651 0.679 0.904 0.964 0.974 1.167 ^Metabolism rates noted based on tests actually determined from the following authoritative sources: `A.S.H.V.E. Research Laboratory;1Becker and Hamalainen; *Douglas, Haldane. Henderson and Schneider; ^Henderson and Haggard; and `Benedict and Carpenter. Metabolic rates for other activities estimated. Total heat-dissipation integrated into latent and sensible rates by actual tests for metabolic rates up to .1250 Btu per hour, and extrapolated above this rate. Values for total heat dissipation apply for all atmos pheric conditions in a temperature range from approximately 60 to 90 F dry-bulb. Division of total heat dissipation rates into sensible and latent heat holds only for conditions having a dry-bulb temperature of 79 F. For lower temperatures, sensible heat dissipation increases and latent heat decreases, while for higher temperatures the reverse is true. Table 5. Degrees of Perspiration for Persons Seated at Rest Under Various Atmospheric Conditions Degree of Perspiration* Atmospheric Condition 95 Per Cent Relative Humidity 20 Per Cent Relative Humidity E.T. Forehead clammy Body clammy................ ................... .......................... Body damD ......... Beads on forehead Body wet Perspiration on forehead runs and drips. Perspiration runs down hody 73.0 73.0 79.0 80.0 84.5 88.0 88.5 D. B. 73.6 73.6 79.7 80.8 85.4 89.0 89.5 W.B. 72.4 72.4 78.4 79.4 84.0 87.6 88.1 E.T. 75.0 75.0 81.0 87.0 86.5 94.0 90.0 D. B. 87.0 87.0 97.5 109.4 108.5 125.2 116.0 W. B. 60.7 60.7 67.5 75.2 74.6 85.4 79.5 "Forty per cent of subjects registered degree of perspiration equal to or greater than indicated. 73