MIL-HDBK-1011/2
APPENDIX A (continued)
1.4
The Bioclimatic Chart. If the plotted point falls within the
comfort zone, conditions are comfortable in the shade and in still air (air
movement less than 5.0 fpm or 0.026 m/sec). If the point falls outside the
comfort zone, corrective measures are necessary to bring conditions into the
comfort zone. If the point is to the left of the comfort zone, additional
solar or surface radiation is needed. If the point is the right of the
comfort zone, additional air movement is needed. If the point is below the
comfort zone, additional moisture is needed and if above, dehumidification is
needed. For the following examples, see Figure A-1.
a)
Comfort Zone: Point A--78deg.F (25deg.C) and 50 percent
relative
humidity.
No corrective measures needed; comfort in shade and still air.
b)
Air Movement: Point B--90deg.F (32deg.C) and 35 percent
relative
humidity. Corrective measure: air movement of 197 fpm (1.0 m/sec) is
required for human thermal comfort.
c) Moisture: Point C--86deg.F (30deg.C) and 20 percent relative
humidity. Corrective measure: lower the temperature by evaporating water
with the attendant effect of increasing the humidity. Note that comfort could
also be attained by providing air movement of 98 fpm (0.5 m/sec).
1.5
Variations in Clothing and Activity Level. The comfort zone
temperatures of Figure A-1 shall be decreased when the average steady state
activity level of the occupants is higher than near sedentary (1.2 met). The
acceptable temperature depends both on the time average activity level and on
clothing (clo) insulation (refer to Table A-2). The acceptable temperature
for activity levels between 1.2 and 3.0 mets can be calculated as follows.
EQUATION:
Total Clo = 0.82 (sum of individual items)
(4)
t+active, = t+sedentary, - 5.4 (1 + clo)(met - 1.2)deg.F
(5)
EQUATION:
or:
t+active, = t+sedentary, - 3 (1 + clo)(met - 1.2)deg.C
EQUATION:
(6)
where:
t
=
the operative temperature,
clo =
clothing insulation level (clo units), and
1 clo = 0.155 m.2- deg.C/watt
met =
metabolic activity rate (met units).
For example, in a machine shop where the average activity from Table A-1 is 2
mets and the clothing is 1 clo, the upper and lower temperature boundaries of
the comfort zone should be moved to the left as in Equation 7 or 8.
EQUATION:
5.4 (1 + 1 clo)(2.0 - 1.2) = 5.4 (2)(0.8) = 8.6deg.F
(7)
EQUATION:
3 (1 + 1 clo)(2.0 - 1.2) = 3 (2)(0.8) = 4.8deg.C
(8)
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