look for
Putting WaterSense® to Work
Laboratory Eliminates
Single-Pass Cooling
Sector: Laboratories; Focus: Mechanical Systems
Project Summary
The U.S. Environmental Protection Agency's (EPA's) Mid-Continent
Ecology Division Laboratory (MED) is located in Duluth, Minnesota.
MED consists of 10 buildings with 88,577 gross square feet of
conditioned space. The laboratory houses both biology and chemistry
laboratories and a large aquatic culture unit. Significant features
include 50 laboratory rooms, seven constant temperature rooms,
administrative offices, and a library. MED has used water from Lake
Superior to support its ecotoxicology research since the laboratory
opened in 1970.
Since 1993, MED has been implementing a comprehensive program to
reduce potable water use. in the late 1980s and early 1990s, MED was
using up to 10 million gallons of potable water per year, mostly for
single-pass cooling of the building or research equipment. Taking
advantage of its proximity to Lake Superior, MED made a concentrated
effort to eliminate all uses of potable water for non-contact, single-pass
cooling and replace it with lake water. As a result, MED was able to
reduce its total potable water consumption by 90 percent. Instead of
sending the lake water to the sanitary sewer, however, once the water
is used, it is sent directly back to Lake Superior. Since the cooling
water doesn't come in contact with any sources of contamination, it
can be returned in the same quantity and quality as before without any
needed treatment.
In addition, from a 2009 water assessment at MED (see the discussion
in Section A.2: Federal Agency Implements Comprehensive Water
Management Strategy), EPA noted that a significant amount of potabie
water was still used to supply single-pass cooling of an ice machine. At
a flow rate of 0.54 gallons per minute (gpm), MED was discharging
approximately 283,000 gallons of water per year to the sewer just to
cool the ice machine. As a result of the assessment, MED recalibrated
the cooling water control valve to only allow water to flow when needed
for cooling. Ultimately, MED decided to eliminate this single-pass
cooling water use by replacing the ice machine with an ENERGY
STAR® qualified, air-cooled model. This replacement allowed MED to
completely eliminate the use of potabie water for single-pass cooling at
the facility, and even further reduce its overall potable water
consumption.
Case Study
Highlights
•	Facility name: EPA's Mid-
Continent Ecology Division
Laboratory
•	Location: Duluth, Minnesota
•	Number of occupants: 175
•	Building size: 88,577 gross
square feet
•	Water savings: Reduced
potable water use by 90 percent,
or approximately 7.5 million
gallons per year, in addition to
saving 283,000 gallons of water
per year from replacement of
water-cooled ice machines
•	Cost savings: Approximately
$75,000 per year in water and
sewer costs from replacing
single-pass cooling, and $2,800
in water and sewer costs per
year from replacing the ice
machine
PHONE (866) WTR-SENS (987-7367) WEBSITE www.epa.gov/watersense EMAlLwatersense@epa.gov
A rn* EPA-832-F 14-002-J
WtlVA July 2014

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Savings Summary
By shifting to using lake water for non-contact, single-pass cooling, MED was able to reduce its potable water use
by 90 percent between 1993 and 2003, which resulted in a water savings of approximately 7.5 million gallons per
year or 55.4 million gallons in total, as illustrated in Figure 1.
Figure 1. MED Potable Water Use, 1987 to 2003
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Reducing potable water use saved MED both water supply and sewer costs, since the lake water used for non-
contact, single-pass cooling was sent back to Lake Superior instead of the sanitary sewer. This results in savings
of approximately $75,000 in water and sewer costs per year.
In 2009, MED spent approximately $3,500 to replace the water-cooled ice machine with the ENERGY STAR
qualified, air-cooled model. In addition to saving an estimated 283,000 gallons of water per year, MED saved
$2,800 per year in water and sewer bills and realized a payback period of less than two years from this
installation.
Overall, MED has reduced its potable water use from approximately 9 million gallons per year in the early 1990s
to only 884,000 gallons in 2010. In 2011, MED initiated plans to install WaterSense® labeled flushing urinals and
dual-flush toilets to further reduce its potable water use. The facility's commitment to water savings has helped
EPA to meet its Agencywide water reduction goals.
Acknowledgements
EPA's WaterSense program acknowledges EPA Water Management Coordinator Dexter Johnson, EPA
Sustainable Facilities Practices Branch Chief Bucky Green, and EPA MED Facilities Manager Rod Booth for
providing information for this case study.
Learn More
To learn more about water efficiency in commercial and institutional buildings, visit the WaterSense website at
www.epa.gov/watersense/commercial to access WaterSense at Work best management practices, tools, case
studies, and more.

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