Basic Documentation

Siemens Industry, Inc. Page 5 of 10
Document No. 149-980
1. Small Testing and Analysis Facility
These laboratories are often small commercial
operations with only one or two laboratory rooms.
Technicians or workers conduct routine and
repetitive testing that can involve daylong use of the
fume hoods. Generally, the fume hoods are limited
in size (5- or 6-feet wide units) and the testing
requires only small amounts of non-toxic chemicals.
Such facilities are usually best served by a CAV 1-
Position system and the fume hood exhaust can
sometimes include a shut down provision. (See note
4 in Table 1.) If the facility is larger, having several
laboratory ro
oms, a CAV 2-Position system may be
appropriate.
VAV systems, which provide maximum benefit when
fume hood sashes are closed, would probably not
achieve the lowest life cycle cost since the fume
hoods in these facilities may be in use for long
periods of time and perhaps all day long. Also, since
the facilities are small, they probably do not have
any high-level support personnel who are needed to
maximize a VAV system's potential or to ensure that
an LAF system is properly functioning.
2. Small College
Undergraduate chemistry teaching laboratories
typically operate for only a limited amount of hours
throughout the year. For this reason, a CAV 2-
Position type of system is ideally suited for this
application. A VAV or LAF system would probably
not achieve sufficient additional energy savings to
justify their higher cost. Also, because of their
modest size, small colleges generally do not have
high-level facility personnel who can maximize the
potential of a sophisticated VAV system or ensure
an LAF system is functioning properly. As an
alternative, a simple CAV 1-Position system might
be appropriate if the fume hood exhaust can be
equipped with a shutdown provision. (See note 4 in
Table 1.)
3. Large College or University
Since larger academic teaching laboratories typically
operate during a specific time during the day, they
are excellent applications for a CAV 2-Position type
of system. Also, if the lab will not be utilized for
extended periods (such as a summer semester),
additional savings might be attained if the fume hood
exhaust can be shut down. (See note 4 in Table 1.)
A simple CA
V 1-Position system will likely waste too
much energy during the unoccupied periods. A VAV
type of system will usually not provide enough
additional energy savings to justify its increased
cost. However, a VAV system may be beneficial in
very large teaching laboratories because it can lower
the overall room sound level when the fume hood
sashes are not fully open. LAF type systems may
not result in the lowest life cycle cost due to their
significantly higher initial cost and the extra care that
the fume hood users must exercise.
4. University Research Laboratories
Large universities often have many smaller
laboratories where research is conducted under
contracts to private firms or under government
grants. These laboratories do not operate according
to a fixed schedule and the fume hoods are utilized
at unpredictable times and for varying lengths of
time. A simple CAV 1-Position system will waste far
too much energy when the fume hoods are not
being used. A CAV 2-Position system is also not a
good fit since there is no predictable occupancy
schedule. A VAV type of system is usually the best
type of system for these applications. An LAF 1-
Position system is a possible alternative, but will
probably not return as much energy savings as a
VAV system.
5. Government Agencies
Government agency laboratories are found at the
federal, state, provincial and local level. This
includes crime labs and regulatory agencies that test
for compliance with stack emissions, wastewater
discharge and other environmental related factors.
These types of facilities mainly employ lab
technicians who conduct repetitive testing during a
fixed daily occupancy schedule. Fume hoods are
usually modest in size (6-feet wide units) and the
technicians may be at their fume wood for most of
the day.
A simple CAV 1-Position system will waste too much
energy during unoccupied periods and may cause
too much ventilation related sound in large
laboratories. Therefore, these applications generally
favor the CAV 2-Position system even though a VAV
or LAF 2-Position system may also be a good fit.
These types of laboratory applications are likely to
require a thorough life cycle analysis to determine
the most applicable type of system.