Energy
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This
retrofit project started out with the aim of reducing the energy consumption at this
417,463 square foot office tower located in Beverly Hills, CA. The original design of the HVAC system utilized
discharge static pressures as high as 6.0 inches W.C., and had 1,250 kW worth of electric
heat installed, as well as 1,000 HP of constant speed, backward inclined supply fans.
There had
been a previously failed attempt to convert the floor by floor fan systems to operate with
a full airside economizer, and a previous “energy retrofit” project that had
downsized one of the chillers by 15%, and cut the cooling tower capacity by 33%.
During the
summer, the constant speed fan systems essentially ran at full power, the chillers ran on
their current limiters, and the cooling tower system was providing 93°F to 95°F
condenser water back to the chillers, with leaving condenser water off the chillers
between 104°F and 106°F on humid days.
As a part of
our Energy Retrofit Project, both chillers were replaced with units 27% larger at the same
power draw, and the chilled water, condenser water and supply fans were converted to
variable flow, premium efficiency. The supply
fan motors were reduced in size by 25%, and the fans were fitted with inverter grade
motors. 50% more cooling tower capacity was
added, and the cooling towers were converted to variable speed operation. A new floor by floor economizer section was added
to allow the system to use outside air when possible.
The existing Siemens DDC system was upgraded with our proprietary sequences of
operation to keep everything under control, and to provide data for energy tracking.
As a result,
the energy consumption has dropped by 26%, and now the entire chiller plant operates at an
average of approximately 0.59 kW per ton. This
efficiency would have been higher, but the building was equipped with a blow-through,
forced-draft counterflow cooling tower
system, using approximately twice the energy of draw-through cross flow or counter flow
cooling towers, and there was only enough budget available to augment the cooling tower
capacity, not replace it outright.
These savings occurred over a very warm year, and
with an increase in occupancy of 13%. |
