Basic Documentation

Page 8 of 10 Siemens Industry, Inc.
Document No. 149- 980
Life Cycle Cost Analysis
As previously stated, a life cycle cost analysis may
be necessary to determine the most advantageous
type of laboratory ventilation system in some
situations. However, a particular type of system may
still not be acceptable if the ventilation system's
limitations (indicated in Table 2) are unacceptable. It
sho
uld also be emphasized that although a
particular type of system may seem to provide the
most advantageous life cycle cost, it may not be the
best solution for the intended application based
upon other considerations. These include lack of
system flexibility and expandability.
You should also consider the availability of a facility
support staff that can ensure proper ventilation
system operation and the achievement of the
anticipated energy savings. When determining a
system's life cycle cost, the training of facility
operating personnel is a valid consideration. More
complicated systems (such as VAV) and more
advanced equipment (such as LAF fume hoods) will
incur additional costs to keep facility personnel
trained on the operation, testing and monitoring of
the systems and associated equipment.
Life Cycle Energy Cost
When compiling a system's life cycle cost, a key
factor is the overall energy cost associated with
each type of system over its useful life. To estimate
the energy cost associated with a particular type of
ventilation system, determine the average annual
cfm using the following steps:
1. Determine each fume hood's average
annual cubic feet per minute (cfm). If a
laboratory room's general exhaust is present
also determine the general exhaust average
annual cfm by the procedure listed in Table
3.
2.
Total the fume hood average annual cfm for
all fume hoods that will be served by the
ventilation system. If a general exhaust is
present, also total each room's general
exhaust average annual cfm and add it to
the totalized fume hood average annual
cubic feet per minute. This results in the
total average annual laboratory cubic feet
per minute.
3. Determine the annual energy cost by
multiplying the total average annual
laboratory cfm (from Step 2) by the facility's
annual energy cost per cubic feet per
minute. This typically ranges from $3 to $6
per cfm in the U.S.