Knowledge Articles

UVC Lights Keep Hospital Cool, Efficient

Rio Grande Regional Hospital Projects Annual Energy Savings of $500,000

The rapidly rising cost of air conditioning energy is a problem for hospitals everywhere, and McAllen, Texas, is no exception. In a town where over 90˚F days are common yearround,
and the mercury can top the 100˚ mark even in winter, the seasons might be described as “hot and hotter.” But at McAllen’s
Rio Grande Regional Hospital, administrators are staying cool
with the knowledge that — even in the face of a 33 percent utility
rate hike — their electric bill has declined over the past two years.
What accounts for this phenomenon? You might be surprised.
“We attribute it to the incorporation of UVC lights into the
air handling systems,” answered Oscar Molano, director of
plant operations for the hospital. “We were looking for a way
to save on a/c energy costs without compromising air quality
or patient comfort.”
Th ey found the light (UVC), so to speak.

THE WONDERS OF UVC

Working with Rio Filter Supply Co. of Harlingen, Texas, Molano fi rst learned that high-output ultraviolet-C band
(UVC) devices have become a popular addition to new and
existing HVAC systems because of their multiple performance
benefi ts. Th e energy emitted by the UVC devices is considered
the most germicidal in the ultraviolet spectrum.
Properly installed in air handlers, high-output UVC lights are
designed to penetrate even the tiniest microbes to destroy their
DNA and RNA, killing or deactivating them. In this manner, the
lights eff ectively degrade mold and other organisms that sometimes
grow deep inside HVAC systems, as well as airborne microbes that
circulate through these systems to the occupied space.
Decades-old studies have shown that even a microscopic
layer of organic buildup on a/c coil fi ns can create a noticeable
drop in system effi ciency. By eliminating this buildup and preventing
its recurrence, UVC devices are designed to keep coils
continuously clean. Th is, in turn, lowers HVAC energy costs by
improving heat transfer and increasing net cooling capacity.

This graph shows the energy savings achieved at Rio Grande Hospital in
2007, as compared to energy consumed in 2006. (Information provided
by Steril-Aire.)

IAQ MAINTENANCE BENEFITS

UVC energy is designed to destroy airborne microbes,
including all types of viruses and bacteria. It can help to
maintain cleaner indoor air and reduce the risk of crossinfection
in health care facilities. Th ough Rio Grande has
not yet studied this aspect of UVC performance, some hospitals
have reported reductions in nosocomial infection rates since
adopting the technology.
UVC also is designed to help control indoor humidity and
comfort levels. It can accomplish this end by keeping air conditioning
components running cleanly and effi ciently and improving
airfl ow through the coils. At Rio Grande, all 26 AHUs are
now running in “as new” condition, said Molano.
“Our nursing staff , patients, and others seem very happy with
the air quality in the facility,” he added.

In his estimation, HVAC maintenance has also been enhanced.
Th ough the hospital still does occasional pressurewashing
of a/c coils with water, they have eliminated the use of
acid for cleaning. In addition, drain pans stay clean and free of
organic debris, so no further cleaning of these components has
been needed, said Molano.
Rio Filter Supply performs all services on UVC Emitters, including
periodic checks and measurements of performance.
“Of course, we are pleased about the enhancement to our already
good IAQ, and with the ability to reduce or eliminate certain maintenance
tasks,” said Molano. “But right now, the energy savings we
are achieving with UVC are fi rst and foremost. Th is technology has
tremendous potential for all types of buildings and homes.”
It should be noted here that the 320-bed hospital has received
the Distinguished Hospital Award for Clinical Excellence for
fi ve years in a row (2003 – 2007) from HealthGradesT, considered
one of the nation’s leading sources for health care quality
information. Th is places the hospital among the top 5 percent of
all hospitals in the nation.

CUTTING BACK THE CHILLERS

At Rio Grande Regional, 17 air-handling units (AHUs) are nine years old and range from 20 tons to 80 tons. Nine AHUs are four years old and are 70 tons to 80 tons. Aft er reviewing the potential benefi ts, Molano approached the hospital’s CEO and received approval to retrofi t the 26 AHUs with UVC on a phased basis. “We started early in 2005 and converted one or two AHUs every month thereaft er,” said Molano. Th e devices used at the hospital are Steril-Aire DE (double-ended) Series UVC Emitters™, which are designed for installation in large commercial HVAC systems. “As our UVC retrofi t program has progressed, we have seen a continuing and dramatic improvement in energy performance,” said Molano. Here is what Molano and the hospital discovered: • Before any UVC devices were installed, the four 465-ton chillers serving the hospital were running at 99 percent capacity. According to Molano, chilled water “in” measured at 43°, while chilled water “out” measured at 64°. • About 18 months later, aft er most of the AHUs had been equipped with UVC, the same chillers were running at only 62 percent capacity. According to Molano, chilled water “in” remained at 43°, but chilled water “out” temperature had decreased to 53°, an 11 degree drop. • During that period, electrical usage (in kilowatt hours) declined 20.64 percent, said Molano. Th is essentially canceled out an equivalent rise in utility rates from $.06 per kWh to $.08 per kWh. As a result, with the addition of UVC throughout the hospital in 2005 and 2006, the electrical energy costs from 2005 to 2006 remained at a constant average of $166,900 per month. By fall of last year, as Rio Grande was wrapping up the conversion to UVC, hospital authorities determined the hospital was now too cold, even with the chillers running at reduced capacity. In late October, the hospital shut down two chillers completely, along with the accompanying chilled-water pumps, condenser water pumps, and cooling towers. According to Molano, the two operating chillers are now running at 80 percent capacity, with chilled water “in” at 43° and chilled water “out” temperature at 60°. Kilowatt hours continue to decline, he said, pointing out that from January through May of this year, energy expense was down $240,885 compared to the same time period in 2006. Based on this trend, annual energy savings are projected to be in the $500,000-plus range. “Needless to say, the recent cutback to two chillers will bring even more signifi cant reductions in our energy cost,” said Mola-no. “UVC technology has made a remarkable diff erence here. We used to need four chillers even when the temperature outside was 70°, and now two chillers do the job at 90°.”

This chart shows the breakdown of utility cost savings achieved at Rio Grande Hospital after it installed UVC lights in the hospital’s air-handling units.
(Information provided by Steril-Aire.)

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