MIL-HDBK-1011/2
APPENDIX C (continued)
Wi = ))) ft2 = ))) ft2
(15)
Calculate the inlet window area
for the proposed design, Wi.
RFi = ))))))) = )))))))
(16)
for partially open, windows, window
type, screens, etc., from Table C-5 and Figure C-6.
Calculate the effective open inlet are, Ai. Ai = ))) ft2 = ))) ft2
(17)
Ai = Wi x RFi
Ao = ))) ft2 = ))) ft2
(18)
Calculate required open outlet area, Ao.
Ao = A x Ai / [(Ai2 - A2)]
Wo = ))) ft2 = ))) ft2
(19)
Calculate the outlet window area
for the proposed design, Wo.
RFo = ))))))) = )))))))
(20)
for the outlet openings from Table C-5.
(21)
Calculate the effective outlet opening,
Ae = ))) ft2 = ))) ft2
Ae.
Ae = Wo x RFo.
(22)
Compare the required outlet opening with the
effective outlet opening:
Worst Month: )))))))))))))))
2nd worst month: ))))))))))
Ao = )))))))))))))))))))))
Ao = ))))))))))))))))))))
Ae = )))))))))))))))))))))
Ae = ))))))))))))))))))))
If Ao < Ae, then the required air speed will be obtained and comfort can
be expected. If Ao > Ae, then the required air speed will not be
obtained.
If required air speed is not obtained, possible methods to obtain the
required air speed are to:
a)
Increase the size of the openings.
b)
Increase the effectiveness of the openings by changing window
type, removing screens, or removing interior partitions.
c)
apart, rotating the building, relocating windows, elevating the building, or
adding wingwalls.
1.2
ASHRAE Wind and Thermal Buoyancy (Stack Effect) Formulae. The two
driving forces producing natural ventilation in a building are wind pressure
and thermal buoyancy (the stack effect). The following is a summary of
formulae for calculating interior airflow.
1.2.1 Flow Due to Wind--Single Opening. Factors affecting ventilation
variation in velocity and direction, and local obstructions such as nearby
buildings, hills, trees, and shrubbery. For a space with only a single
opening, use Equation 8.
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