Minimum Efficiencies for Water-Cooled Chillers
Full Load
IPLV
Capacity
COP (EER)
COP (kW/ton)
greater than 702 kw (200 tons)
or less than or equal to
1757 kw (500 tons) =
5.7
(19.4)
6.1
(0.58)
greater than 1757 kw (500 tons) =
5.9
(20.0)
6.3
(0.56)
Because of typical manufacturing practices,
air-cooled and small water-cooled chillers
(typically less than 527 kW (150 tons)) are not
available in multiple efficiencies for each
available capacity. Only one model, and therefore,
only one efficiency is available from a manufacturer
for a given capacity. The minimum efficiencies
stated above for air-cooled and small water-cooled
chillers are low enough to allow all of the major
chiller manufacturers to competitively bid.
Specifying a higher efficiency for air-cooled and
small water-cooled chillers will limit competition
and may require a sole source justification.
Larger water-cooled chillers (greater than 527 kW
(150 tons)) are available in multiple efficiencies
for each available capacity. The minimum
efficiencies stated above are only guidelines in
specifying efficiencies. The designer will be
responsible for developing a life cycle cost
comparison between available efficiencies to
determine the optimum alternative. The decision to
specify a more efficiency liquid chiller than the
minimums defined above will typically be driven by
the kW-hour costs, the electrical demand costs, and
the chiller's annual energy usage. A designer
should develop a sole source justification (if
applicable) to procure the most life cycle cost
effective chiller applicable. Coordinate chiller
efficiencies with chiller manufacturers prior
finalizing the specification.
The driving force in the procurement of higher
efficient equipment is Executive Order 12902.
Executive Order 12902 specifies that energy
consuming products be selected which are in the top
25 percent of their class for energy efficiency or,
at a minimum, at least 10 percent better than
current federal minimum standards, to the extent
practical and cost effective.
Full and part load efficiencies for gas-engine
driven liquid chillers will have a COP of between
1.0 and 2.0 based upon operating conditions (i.e.,
with heat recovery, without heat recovery, etc.). A
SECTION 15620A
Page 14
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