Process Water Efficiency
HEALTHCARE - TOP 5 GREEN BUILDING STRATEGIES
EPA Publication 909-F-07-001
What? Water is an increasingly visible and expensive resource. Process water - used to
operate building systems including boilers/chillers, cooling towers, and sterilizers
- comprises about 75% of hospital water use. Reducing water use can lower
operational costs and should be part of an integrative design process for
construction.
Why?
7 Enhanced Community Reputation:
• Water efficiency reduces environmental impact
• Demonstrates environmental stewardship
Environmental/Staff/Patient Benefit:
• Lower environmental
impact on drinking water
sources and waterways
receiving wastewater
Cost Competitive:
• Improves facility's overall
operational efficiency
• Process water technologies
are readily available and
well tested with documented savings
How?
Case
Studies
Reuse cooling tower water and boiler blowdown
Recover and reuse condensate
Increase efficiency or replace water-cooled equipment
Emory University
Green Guide for Health Care (GGHC) Criteria: Construction: Water Efficiency and Operations: Water
Conservation www, gghc. ora
This is one of 5 Building Healthy Hospitals case studies developed by EPA's Pacific Southwest Regional Office,
with Resource Conservation Challenge and Pollution Prevention funds.
www.epa.qov/reqion09/waste/p2/pro1ects/hospart.html
Indoor Air • Sustainable Flooring • Process Water Efficiency • Lighting Efficiency • Energy Efficiency
Building Healthy Hospitals 1
This fact sheet was produced by EPA's Pacific Southwest Regional Office. Mention of trade names, products, or services does not
convey, and should not be interpreted as conveying official EPA approval, endorsement, or recommendation.
Printed on 100% recycled paper, 50% post-consumer content - process chlorine-free
2007
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Process Water Efficiency
HEALTHCARE - TOP 5 GREEN BUILDING STRATEGIES
CASE STUDY: CONDENSATE WATER RECOVERY
Applicability:
Environmental
Impact:
Other Benefits:
New construction or major renovation projects;
condensate water recovery can be done at any
healthcare facility not connected to a central cooling
plant
Reduced use of cooling tower make-up water saved
900,000 gallons of water per year.
Long term operating efficiency.
Background
Normal operation of air handling units produces condensate water from
cooling coils that typically drains to municipal sewer systems.
Condensate is characteristically clean water that can be captured and
reused for other non-potable water applications.
Performance
The total water use at Emory's Winship Cancer Institute is estimated to be 80 percent less
than a comparable facility through the use low flow fixtures and process water efficiency
improvements. This water use efficiency is in large part the result of Emory's conservation
efforts in high water use areas, including process water associated with HVAC systems. The
Winship Cancer Institute recovers condensate water from the air handling units of its
cooling system, for use as make-up water in the cooling towers. This reduces water needed
for the cooling towers by approximately 900,000 gallons per year. Features of the system
include:
• Condensate recovery works by gravity flow; A drain line runs from each air
handling unit to a central connection point in the penthouse, and from there a
single line runs to the cooling towers.
• Collected condensate water enters the cooling towers at temperatures between
50 and 60 °F.
• A 3-way valve in the line feeding make-up water to the cooling towers allows the
system to draw from reclaimed condensate or domestic water. The cooling
towers have a level control to determine the amount of condensate needed in the
towers, controlling the 3-way valve accordingly.
Building Healthy Hospitals
An EPA P2 Project
2007
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Process Water Efficiency
HEALTHCARE - TOP 5 GREEN BUILDING STRATEGIES
Normally, the cooling towers need more make-up water than can be recovered
from the condensate, in which case the system uses supplemental domestic
water.
When occasionally there is some excess condensate, it drains to the municipal
sewer; without the recovery system, all condensate would be sent to the sewer.
Each air handling unit has a two way valve in the condensate line to allow for the
system maintenance.
All condensate pans in air handling units throughout Emory's campus are treated
to control algae growth to keep drain lines from clogging and pans from
overflowing. The condensate pans at the Winship Cancer Institute are treated
the same way as every other air handling unit and no extra maintenance costs
are incurred.
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Building Healthy Hospitals
An EPA P2 Project
2007
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Process Water Efficiency
HEALTHCARE - TOP 5 GREEN BUILDING STRATEGIES
Cost
Installing a condensate recovery system requires additional engineering design and added
plumbing costs to pipe condensate from the point of recovery to the cooling towers.
Because of the gravity fed design and relatively close proximity between the air handling
units and the cooling towers, Emory realized a payback on this project of about 5 years (see
cost/benefit analysis). This payback period depends on the cost of raw water (from a
municipal source) and the cost of piping (largely dependent on the distance) required to
collect and return condensate to the system.
COST/BENEFIT ANALYSIS - WINSHIP CANCER CONDENSATE RECOVERY
Initial Cost
Water Savings
Cost Savings
Simple Payback
Condensate Recovery
System
$45,000
900,000 gallons
$4,860
Approx. 5 years
Comments
Costs include piping system from air handling
units to cooling towers and associated hardware.
Nearly all condensate recovered is reused in
make-up water; in rare instances, excess
condensate is discharged to the municipal sewer
system.
2005: $5.40 per 1,000 gallons of water
2006 and beyond: Significantly higher - water
costs may rise 40 percent or more
annually for several years.
Payback is estimated at 9.25 years based on
2005 water costs and is longer than Emory would
normally require for capital projects, but water
costs are expected to rise sharply in the greater
Atlanta area. As a result, Emory expects cost
savings from water conservation to exceed the
costs of the condensate recovery system in
approximately 5 years.
Case Study Vitals
The following summarize success criteria for implementing this project at other healthcare
facilities:
• Consider the condensate recovery potential as well as the amount of make-up water
needed when evaluating the effectiveness of a condensate recovery system. Ideally,
75 percent or more of the recovered condensate should be used.
• Though Emory installed a condensate recovery system at a building with an
independent cooling system, the same strategy could be implemented at a central
cooling plant. For example, Emory has implemented a similar system at one of the
three central cooling plants serving the campus. Condensate water from one of the
buildings served by the plant is collected and pumped back to the plant using the
Building Healthy Hospitals 200?
An EPA P2 Project 4
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Process Water Efficiency
HEALTHCARE - TOP 5 GREEN BUILDING STRATEGIES
same route followed by the chilled water lines. The need for a pump and the longer
distance to the plant increase the equipment cost; however, this system collects and
reuses approximately 3,000,000 gallons of water per year, resulting in a similar
payback to the system at Winship Cancer Institute.
CASE STUDY: INTEGRATED WALK-IN REFRIGERATION SYSTEM
Applicability:
Environmental
Impact:
Other Benefits:
New construction or major renovation projects; can be
applied to cool walk-in refrigeration coolers or freezers
in kitchens or laboratories.
Reduced use of domestic water needed to cool walk-in
refrigerator compressors by 11,826,000 gallons per
year.
Long term operating efficiency.
Background
Healthcare facilities often have large, walk-in refrigerated areas for laboratory use or food
storage. These areas can be chilled using a variety of technologies, but are often served by
an independent compressor that cools the area using chilled air or water. Compressors
chilled by water typically draw from domestic water sources and discharge to municipal
sewer systems.
Each of the three laboratories at the Winship Cancer Institute is
equipped with three 70 to 100 square foot walk-in refrigerators used to
store reagents and research materials, chilled to 39° F.
Performance
Emory has integrated the cooling system used to cool the walk-in
refrigerators with the chilled water loop that also serves the air handling
units. Rather than using domestic water to cool the compressors used to chill these rooms,
Emory has routed already chilled water from the building's air handling units through the
compressors, then returning the water to the chillers. This innovation was made easier
because the compressors used to chill the walk-in refrigerators were located in the
penthouse in close proximity to the air handling units. The water lines connecting the air
handling units and compressors are equipped with a temperature sensor; if the temperature
in these lines should increase above 60° Fahrenheit, domestic water is used to cool the
compressors until the supply water from the chillers drops back below 60° F.
Because it relies on already chilled water generated from air conditioning systems, the
efficiency of this strategy is directly linked to the frequency of operation of the building's air
conditioning system. Georgia's warm, humid climate requires significant use of air
Building Healthy Hospitals 200?
An EPA P2 Project 5
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Process Water Efficiency
HEALTHCARE - TOP 5 GREEN BUILDING STRATEGIES
conditioning systems; therefore, the chillers are used for most of the year. However, the air
conditioning system is typically unused seasonally between December and February during
which time the walk-in refrigerators are cooled using domestic water.
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Cost
Integrating the compressors used to cool the walk-in refrigerators with the air handling unit
chilled water loop requires additional engineering design and added plumbing costs to
connect the two typically separate systems. Depending on the amount of piping required to
make this modification the payback period can range from 1 to 7 years.
Building Healthy Hospitals
An EPA P2 Project
2007
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Process Water Efficiency
HEALTHCARE - TOP 5 GREEN BUILDING STRATEGIES
WALK-IN REFRIGERATION SYSTEM COST/BENEFIT ANALYSIS
Initial Cost
Water Savings
Cost Savings ($)
Payback
Integrated Walk-In
Refrigeration System
$40,000
11,826,000 gallons
$63,840
0.63 years
(7.5 months)
Comments
Total costs to modify all 9 units.
Avoided domestic water use.
Emory pays $5.40 per 1,000 gallons of water.
Cost savings from water conservation exceeded the
costs of the integrated walk-in refrigeration system
in the first year.
Notes: The viability and favorable payback of this project relies heavily on two factors that may or may not
exist at other facilities; namely:
1. Relatively low initial cost because of the close proximity of the compressors used to chill the
refrigerators and the air handling units for the HVAC system.
2. The high use of the HVAC system necessitated in humid and hot southeastern U.S. climates.
-W-4- ' Case Study Vitals
The following summarize success criteria for implementing this project at other healthcare
facilities:
• The proximity of the walk-in refrigerator compressors and air handling units helped
minimize the cost of integrating these systems.
• This type of system can be applied to cool any walk-in refrigerators, not just those in
laboratories.
The system used at Winship Cancer Institute is appropriate for other facilities in warm
weather climates. Alternatively, cooler climate facilities could consider implementing a
similar strategy using a heat exchanger.
Building Healthy Hospitals
An EPA P2 Project
2007
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