ACEC Colorado 1995 Engineering Excellence Merit Award
A CRISIS IN COMFORT
Colorado Springs, Colorado
Take a hospital’s campus chilled water system . . .
The Penrose Hospital campus in Colorado Springs, Colorado, was 836,000 square
feet and growing. As the premier health care provider in the Pikes Peak region
of the Rocky Mountains, patient expectations for quality health care were
The core of the facility’s comfort control system, the central
chilled water system, was not getting the cooling job done. Patients
were uncomfortable, bed counts were dropping, and the engineering
department was continually attempting to address the problem:
a costly chiller addition was being considered.
. . . and make it work!
THE ENGINEERING CHALLENGE CROSSED TECHNICAL, COMMERCIAL, ENVIRONMENTAL,
AND SOCIAL BOUNDARIES:
- System problems were identified. New solutions had to be developed at the
most innovative level. The traditional remedy of adding more pumps only
made matters worse. Adding another large central chiller looked like the
- The complexity of finding and solving the system distribution problems
was amplified by the requirement to simultaneously upgrade the central
chiller plant refrigerant detection system.
- The solutions had to be affordable and implemented with minimal disruption
in patient care.
- In addition to increasing the patients’ comfort level, the general
public should benefit from the environmentally safe solutions.
- State-of-the-art technology was to be superseded by “Future-of-the-art”
technology at every opportunity.
GOOD, OLD-FASHIONED HARD WORK was required to map the entire
chilled water system, which serves nine major buildings. Partnering with the
mechanical contractors and facility team leaders was paramount to identify system
problems, which others had failed to observe.
OPEN BYPASS PIPING WAS DISCOVERED IN THE BASEMENT OF THE 14-STORY PATIENT TOWER:
Differential pressure was not available to deliver chilled water up through
the tower. The original solution, implemented years earlier to boost the flow
up the tower, was failing.
RETURN SIDE PRESSURES, WHEN BOOSTED BY COIL PUMPS, BECAME HIGHER THAN DOWNSTREAM
SUPPLY SIDE PRESSURES: Downstream cooling coils were experiencing reverse water
flow and an unacceptable rise in discharge air temperature.
COOLING COILS WERE PIPED BACKWARDS: A 20% loss in cooling effectiveness was
INNOVATIVE SOLUTIONS for the chilled water distribution problems were implemented:
the anticipated approach of installing another chiller was not going to solve
the problems. Calculations had shown the existing central plant, at 2,200 tons
of cooling capacity, was large enough to handle the campus load of 1,875 tons.
The solutions were simple.
VALVES WERE INSTALLED IN THE SYSTEM BYPASSES and closed, which caused differential
pressures to improve dramatically (from zero to 25 psi minimum): flow was achieved
to the tower.
BOOSTER PUMPS WERE REMOVED: Reverse flows were eliminated.
COIL PIPING WAS CORRECTED: Discharge air temperatures dropped from 80°F
WHILE THE BEAUTY OF THE SOLUTIONS
. . . lay in their SIMPLICITY, implementing them was extremely COMPLEX. Piping
problems were found in all of the buildings. However, the major bypasses that
had to be closed were located in the basement of the 14-story patient tower,
where the chilled water for all floors was piped.
Disruptions in patient care on all floors had to be kept to a minimum.
An eight-phase plan was developed and implemented to sequence
the piping changes as quickly as possible with minimal hospital
RIGID TIME AND BUDGET CONSTRAINTS
. . . were imposed on the project and were met. Upfront savings were realized
on the expected cost: $750,000 had been budgeted for the anticipated new chiller
and pumps (the traditional remedy), while only $250,000 was spent. Anticipated
annual energy savings were calculated to be $75,500. This exceeded the owner’s
requirements for a successful project.
THE GENERAL PUBLIC BENEFITS, as well as the patients, from these
solutions: the chilled water distribution system uses less energy
to deliver more cooling in a manner that is environmentally safer.
Chilled water can now be distributed as needed. Patient complaints have reduced
dramatically. Excess series booster pumping was eliminated. Correctly directed
flow to cooling coils through the use of primary-secondary piping has reduced
energy costs. A Direct Digital Control System controls both the chiller plant
and a new refrigerant detection system. The future chilled water needs of the
facility can now be readily incorporated into this highly efficient system.
THE HOSPITAL IS THE EMBODIMENT OF SOLUTIONS FOR THE FUTURE: use
a thorough investigation to diagnose the problems . . . THEN TREAT THE
DISEASE, NOT THE SYMPTOMS.
A “FUTURE-OF-THE-ART” dual refrigerant monitoring and detection
system was installed in the central chiller plant. An environmentally safer
refrigerant, R123, replaced F11 (an ozone depleting refrigerant) to upgrade
one of the central electric chillers. By meeting the requirements of anticipated
extensive FUTURE mechanical codes TODAY, the system leads the NATION in the
design of refrigeration machinery rooms.
“With the cooperative team effort of engineers, mechanical contractors
and facilities team leaders, the project exceeded all expectations. Even
though the very complex nature of this job required numerous phased shutdowns
for system drain downs, it was completed within a few months’ time.”
“The project was on time, under budget, and will result in significant