Use the cleanest, coolest air source
A vital element in the successful breeze
conditioning system is a supply of clean, cooler, fresh air. While
such an ideal air supply may not be available, common sense dictates
that air being supplied into the building should be from the best
available source. Avoid recirculating air that has just been exhausted
from the building or another nearby structure.
The
noise factor in the ventilation system
The noise level in most commercial and industrial
buildings has become a highly critical matter. Although the ventilating
equipment is only one item in the overall total, its effect should
be carefully considered. If the normal noise level in the building
is low, the noise level of the ventilating equipment should be low;
if the background noise level is high, the amount of noise added
by the ventilation system may be insignificant. For more detailed
sound information, refer to American Coolair Form No. l20-l5.
Economies
from good planning
The greatest economy that can result from good planning
is a breeze conditioning system that achieves its basic purpose.
If it does not do the job for which it was designed, then no economy
has been achieved. Here are a number of other ways in which good
planning can result in substantial savings.
A
unified ventilation system
Frequently, exhaust fans are obtained and installed
to serve a specific need. In many cases, no consideration is given
to a method of coordinating this equipment. Process fans may be
competing with general exhaust fans; loading doors or windows may
be 1cft open needlessly and "short circuit" an otherwise integrated
system.
Use of "make-up
air" fans
A common problem in the average plant is "air starvation".
Exhaust systems throughout the structure may have been well designed
for their intended purpose. However, no consideration may have been
given to the replacement of exhaust air. As a result, the building
may be under severe negative pressure. This situation reduces the
efficiency of the exhaust fans and produces unhealthy and uncomfortable
working conditions. Substantial economy and efficiency can be obtained
by correcting this situation through the use of supply fans or "make-up
air" units.
Controlled
air circulation
Many buildings have adequate exhaust and supply
fans to provide a comfortable environment for the occupants. Unfortunately,
there may be little control over the distribution of the air to
produce the desired results. Good planning will recognize the necessity
for proper air distribution and circulation through the occupied
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areas of the building. Suitable deflectors and baffles can be incorporated
where needed. "Booster fans" or air circulators can be positioned
to take care of trouble spots and augment the direction and velocity
of the air flow. Diffusers may be required lo assist in air distribution.
Drafts and dead spots can thus be eliminated. All of these are inexpensive
aids that can ensure that a well planned system will achieve its important
objectives.
Typical
applications
The following
layout of breeze conditioning systems will illustrate the basic
principles outlined in this handbook. One or a combination of these
plans may be adapted to the specific job under consideration. The
advantages and limitations for each of these layouts are explained
in the accompanying notes.
Rate
of air change method
Rate of air change method
TYPICAL RECOMMENDED
RATES OF AIR CHANGE |
|
Type of Facility |
Cooling |
Ventilation |
| Bakeries, Restaurants, Laundries
& other hot spots |
½ minute |
3 minutes |
| Factories, Shops, Warehouses
& Garages |
¾ minute |
4 minutes |
| Residences. Schools, Offices
& Churches |
1 minute |
5 minutes |
- An adequate
method for small buildings or a single room (50,000 cu.ft. or
less).
- The rate
selected is somewhat arbitrary, usually based on experience with
similar facility or space.
- Velocity
and direction are frequently uncontrolled;
some degree of control is available by regulation of window or
other intake openings.
- Not recommended
where complicated air distribution problems exist.
Rate of air
velocity method
- Illustrations
show 3 variations of some basic system of air distribution. Rate
and direction of air flow is identical in each case. Intake and
exhaust arrangements are adjusted to meet conditions peculiar
to each location.
- This basic
system is recommended for its economy and efficiency for both
large and small buildings.
- Use of wall
fans and PRVs for exhaust requirements is illustrated.
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