Document O1ZyrwYeOgM5GQpaerRj9M4bL
'278
CHAPTER 13
1956 Guide
The Technical Advisory Committee on Weather Design Conditions has suggested that wet-bulb design temperature be taken as that wet-bulb temperature which has been equalled or exceeded in 5 percent of the hours during months of the period of record. While not available for the 1956 edition of The Guide, due to the tremendous task of compiling these data/ it is hoped that they will be available for some stations for future editions.
The wind velocity to be used in design should be that wind velocity which accompanies the design temperatures in each instance, but since these data are not available, the average summer wind velocities for the period of record were taken from U. S. Weather Bureau records revised to 1948. It is pointed out that this is not necessarily the velocity which coincides with the design temperatures, but it may serve as a guide to the designer.
Other weather data, such as daily range of temperature, are useful particu larly when making cooling load calculations for an early morning peak on an east exposure. Daily range of temperature is the difference between the average of the daily maximum dry-bulb temperatures and the average of the daily minimum temperatures. This range is highest in semi-arid or desert regions and at high elevations, and lowest near the oceans or very large lakes. The daily range of temperature (Fahrenheit degrees) in July for the principal areas of the United States can be approximated from the following tabulation:
East Sea Shore............ 12 to 18 Gulf Sea Shore............ 12 to 18 Great Lakes Shore___ 18 to 21 West Sea Shore.......... 15 to 20
East of Mississippi River..............
19 to 24
Mississippi River to Rocky Mountains--24 to 33
Rocky Mountain Area..................................... 33 to42
West Coastal States................................... .20 to 36
Ventilation Rate
The introduction of outside air is necessary for the ventilation of condi tioned spaces. Chapter 6 suggests minimum outdoor-air requirements for representative applications; but it is to be emphasized that minimum re quirements are not necessarily adequate requirements for all psychological attitudes and physiological responses. Where maximum economy in space and load are essential, as in submarines or other restricted spaces, as little as 1 cfm of outside air per person has been found to be sufficient provided that satisfactory ventilation is simultaneously obtained by an adequate decontamination of recirculated air.2
Local codes and ordinances frequently specify ventilation requirements for public places and for industrial installations.. For operating rooms, minimum requirements for safe practice are given in a National Board of Fire Underwriters' pamphlet.* This pamphlet does not require 100 percent outside air in operating rooms, although 100 percent outside air is normally . used and recommended.
Recommended and minimum ventilation .rates for the most common applications are summarized in Table 3. For further general applications, a basis of estimating the cfm per person may be taken as:
1. People not smoking. 2. People smoking......
Recommended
5 Minimum
40 Recommended 25 Minimum ,
The cooling load due to the introduction of outside air for ventilation is : determined once the indoor and outdoor design conditions are fixed. Cal-T'
dilations will be discussed subsequently.
::-r v
Cooling Load
A* m. .......
Anninston . ... CO
Birmingham... CO
Birmingham___ AP
Mobile___
pn
Mobile................. ap
Montgomery..' .CO
Mflaognstgtaofmf e. ryy:; ACOP
733 711
615
143 219
293 226
1893-1947 1893-1945
1939-1947 1872-1947
1940-1947 1872-1947 1938-1944*3
Bangman............. AP
................ CO rhoemx................ AP I?03}*..................AP
6957
3473 1122 1112 2561
1899-1947 1935-1939 1895-1947 1933-1947 1935-1939
**....iFn^ih.;:::"g8*inslow.
AP
4853 4899
Up to 1946 1937-1947
146 1876-1946
Fort Smith........ AP Little Rock........CO
C'knLiiff--/I BakersRfieolcdk.._.._.._..AAPP
545 463 451 282
1882-1945 1945-1947 1879-1942*3 1942-1947
Burbank.-.----- AP Daggett...AP
Lureka..................CO
resno...... ...co
freano............ _ AP Lc* Angeles.....CO
499 740 1925 132 387 281
1937-1946 1931-1947*3
1935-1939 1886-1947 1887-1939 1939-1947
Colo
Oakland... AP Bed Bluff___,. .CO
Red Bluff
AP '
Redding.....;; AP
Sacramento........ CO Sacramento........AP
San Diego........... CO |an Diego........... AP
&an Francisco...CO
an Jose.
no
| ''AP
534 21
305c
346 579 116 22 90 34 164
100 124
1877-1947 1929-1947 1877-1934 1944-1947 1935-1939 1877-1947 1938-1947 1871-1940 1939-1947 ,1875-1947 Up to 1946
1935-1939
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116 105 104
279
Col. 7 Design
- -uibiuht-Bdu
fed
Basis' 1
F
Col. 8 1 Col. 9
Desiga
Wet-Bul3 I Average
Temp. u i 1 Summeb
CoMMor
Wind
Use*
Velocity*
F Mph
95 94 - 95
92 95
95
78 78 5.4
80 8.6
78
99 90 ~65
107
102 105 100
76 6.0
72 70
110 "78 95 76
78 6.2 *70
90 105 103
*90
85 100
65
74
70 65 j
70
7.9 8.8
72 7.9
68
85 91
*65 10.7 70
64 6.9 95 65 95 65 95 65
7.4
5.9 95 95
8.4
95 98 95 95 95
95 95 98 95 96
`78 78 `65
65 65 *78 75 ,76
to to
7.4. 7.9 8.6
sis
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