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On Target: A Complicated and Successful Energy Retrofit Program
Abstract
The Lone Star Gas Corporate headquarters, in Dallas, Texas,
consists of a five building, 355,000 square foot office
complex with buildings ranging in age from 14 - 60 years
old between 20,000 - 100,000 square feet (SF), and with
multiple HVAC systems served by two central plants. The
company was facing the inevitable increase in electric utility
costs knowing that two reactors at a new construction nuclear
power plant would be coming on line over during the next
five years. By taking a proactive stance, a six month
detailed energy audit commenced after a thorough internal
energy analysis was conducted. The result of the audit was
a multi-year $1.7 million retrofit project encompassing
nearly 20 major items would be implemented over three
years. Total energy and cost avoidance savings were
calculated to yield a simple pay back of 1.5 years and a cash
pay out of 3.5 years. Total energy reductions of 32% were
achieved and the predicted economics realized.
The various projects involved the application of nearly
18,000 square feet of window tinting, a total facility
relamping and efficiency improvement project, installation
of more efficient filtration systems, installation of control
valves on the chillwater system, installation of a building
automation system, installation of a plate heat exchanger for
hydronic free-cooling, isolation of after-hours and 24-hour
cooling loads on a separate loop, isolation and conversion of
24-hour steam requirements to reduce excess boiler capacity
and run time, improvement of return air systems, the
replacement and increase of cooling tower capacity,
implement a preventive maintenance program, and improved
operating procedures that focused on demand side
management without thermal storage. The combined results
of these single projects enabled the facility to remove and not
replace 25% of the physical plant cooling equipment (one
single-effect steam absorber) upon reaching the end of its
expected life.
Project costs and avoided savings were tracked monthly
throughout the three year period. Additional energy and
cost avoidance tracking for two more years was completed.
In five years, a positive cash flow of more than $550,00 is
only 9% less than the original projection. Improved
employee comfort and enhanced space conditions have
returned significant benefits to the work force of nearly one
thousand people occupying this facility.
Citation
Kimball, M. A. (1996). On Target: A Complicated and Successful Energy Retrofit Program. Energy Systems Laboratory (http://esl.tamu.edu); Texas A&M University (http://www.tamu.edu). Available electronically from https : / /hdl .handle .net /1969 .1 /6697.