June 99
areas and/or corridors (which are directly
connected with the toilets and janitor closets)
can be drawn in by door undercuts 4 m3/min.
(150 CFM) maximum and/or louvers.
b.
Pressurization: The vestibules and main
entrances shall be pressurized by supplying
ducted conditioned air, a portion (15%) of
which shall be retained in the space to
maintain a positive pressure with respect to
outdoors and minimize infiltration of raw
outdoor air into the conditioned space.
4.
15% of the total supply air volume.
B.
VEHICLE MAINTENANCE/STORAGE: Ventilate the
maintenance section by providing a supply air
ventilation unit and exhaust air system of 8 air changes
per hour (minimum) capacity. The equipment storage
area does not require any mechanical ventilation.
2.5
ENGINEERING CALCULATIONS:
A.
LOAD CALCULATIONS: Calculate the cooling/heating
loads in accordance with the method outlined in
ASHRAE Handbook of Fundamentals.
B.
SAFETY MARGIN: A safety margin of 10% shall be
added to the calculated internal heat gain and loss to
allow for any future increase in internal heat gain or
other load demand. The calculated air quantities for
the occupied spaces shall be based on the addition of
the safety margin.
C. AIR LEAKAGE: An allowance of 4% shall be made for
the leakage of air through the ductwork before it
reaches the occupied spaces. The leakage allowance
shall be applied to the sum of all individual peak air
quantities without any diversity. Do not compute the
supply air fan volume on the basis of block or
zone loads wherein the load (and air volume)
diversities are inherently built in the calculations.
D. STATIC PRESSURE: Add a safety margin of 10% to
the fan total static pressure of the system. The static
pressure calculations shall be based on:
VA Design Guide -- National Cemetery Administration
Page 5 -57
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