Excerpted from a Southface Energy
Institute Commercial Buildings technical bulletin
Water conservation and water
quality have become important issues in Georgia in
recent years. A growing population, especially in
urban areas, is causing stress on existing water
resources and infrastructure, and is forcing all
sectors of society to examine ways to promote efficiency.
The average daily domestic demands in commercial/industrial
settings range
between 20 and 35 gallons per day (gpd) per employee.
Businesses are finding that it makes
good business sense to take advantage of new strategies
that promote water conservation because they benefit
both the bottom line and the environment. Consider
this example: a 25-person office with an existing toilet
size of 3.5 gallons and a 3 flush/person daily average
use— a retrofit to 1.6 gallon toilets that use 54%
less water would save over 37,000 gallons per year.
Reduced water consumption can be achieved
by innovations in plumbing. Water efficiency measures include:
low-flush toilets and urinals (1.6 and 1 gallon per flush
respectively), low-flow showerheads with a maximum of 2.5
gallons per minute (gpm), and kitchen/bathroom faucet aerators
that reduce flow to 2.5 gpm. These are the federal requirements
for new construction as part of the Energy Policy Act of
1992.
Advantages of Water Conservation
Reduced water use means lower
water bills and lower wastewater treatment costs.
Lower energy costs associated with pumping, heating,
and processing water.
Recognition as an environmentally responsible company.
Improved water quality through the reduction of stormwater
runoff.
Determining Water Usage
Create a water budget that includes
the breakdown of water uses, flow rate, temperature,
and quality requirements.
Calculate the present amount of
water used known as a base level. Work to reduce water
consumption below the base level.
Do a self-assessment to identify
target areas for water reduction.
Determine the true cost of water
usage, which includes heating, pumping, pre-treatment,
and labor.
Become a partner in the EPA’s Water
Alliances for Voluntary Efficiency (WAVE) Program that
promotes the efficient use of water in the commercial and
institutional sectors. Visit www.epa.gov/owm/genwave.htm
for more information.
Water conservation checklist
Indoor Methods and Strategies
Test for leaky pipes. Take two
readings from the building’s water meter about two hours
apart during a period when no water is being used. The
reading on the water meter should remain constant, assuming
there are no leaks. Promote employee conservation by
installing water meters for both hot and cold water and
reporting monthly usage rates to employees.
Regulate water pressure to maintain
pressures between 40-50 psi. This will prolong the life
of fixtures. Install pressure-reducing valves on the
intake of the building; but check to see if reducers
are already in place.
Install dual plumbing pipes for
water reuse in all new buildings. This is a forward-looking
decision that permits water recovery from showers, sinks,
and other sources not contaminated with human waste.
Some states and municipalities encourage the use of recovered
water for toilet flushing and landscaping.
Install waterless urinals. The
benefits of installing waterless urinals include the
obvious water savings, reduced maintenance costs, and
improved hygiene. School and office bathrooms are a good
application with savings estimated at 30,000 gallons
per year. The waterless urinal’s installed cost is less
than $500 and is comparable to conventional urinals,
since no supply water plumbing is necessary. Most retrofit
applications have a payback of 3-5 years with typical
water savings from one installation over 13,000 gallons
a year. The Jimmy Carter Presidential Library & Museum
in Atlanta, Georgia has installed 6 waterless urinals.
Increase water pressure in certain
dishwashing and other process applications to reduce
water consumption. Example: Increasing the operating
pressure with a pump caused a minor increase in energy
costs for a dairy bottle washing operation. However,
the water used was reduced from 9 gallons per minute
(gpm) to 1.5 gpm.
Use non-toxic cleaning materials.
These are cost competitive, minimize employee exposure
to toxic chemicals, and benefit water quality.
How a Waterless Urinal Trap Works
The Waterless Company’s patented
Eco-Trap® design allows urine to pass through a
less dense liquid. This liquid provides a trap
keeping odors from the room. This design contains
no valves that could clog or break.
This urinal needs periodic
maintenance which costs less than $100 per year.
Maintenance duties include spraying with cleaner,
replenishing the liquid seal twice a month, and
replacing the recyclable Eco-Trap® 2-4 times a
year.
Use automatic controls to turn off circulation pumps
when not needed. Consider installing an on-demand
circulation system at the hot water fixture furthest
from the water heater. An on-demand system moves
lukewarm water from the hot line back to the water
heater rather than wasting it down the drain. Less
time is needed to supply warm water at the fixture
for hand washing. This can save more than 10,000
gallons per year for a small office.
Outdoor Methods and Strategies
Follow xeriscaping practices. Use
drought-tolerate plant species—often native varieties,
mulch ground cover, and landscape design to reduce irrigation
needs. The seven principles of xeriscaping are: Planning & Design;
Soil Analysis; Appropriate Plant Selection; Practical
Turf Areas; Efficient Irrigation; Use of Mulches; and
Appropriate Maintenance.
Minimize the amount of grass on-site.
Plant ground covers such as clover, wild strawberry,
thyme, or yarrow. Choose centipede, fescue, or buffalo
grass, which are suitable for the southeastern climate.
Consult a landscape architect or a local cooperative
extension service for specific recommendations.
Water heating
Reduce the amount of hot water
needed with low-flow plumbing fixtures.
Install and properly maintain a
high efficiency water heater. Consider a cost-effective
solar water heating supplement.
Reduce the temperature of the water
to 120°F, which provides plenty of hot water. Many systems
are set at 140°F, resulting in wasted energy. Measure
the temperature at major hot water use points if there
is still concern, and adjust if needed.
Install an insulating jacket on
existing water heaters.
Insulate water pipes, especially
the first four feet of all pipes connected to a water
heater. Insulating hot water pipes allows water in the
pipes to stay warmer, reducing waiting time for hot water.
Heat traps located at the top of
water heaters can also save energy. Heat traps can be
either check valve or looped configuration type and help
reduce water siphoning from the tank during standby conditions.
Capture heat from water that would
normally be wasted down the drain and reuse it for other
purposes. Dishwasher wastewater can be used to pre-heat
water entering the water heater. This can be accomplished
with a water-water heat exchanger. These systems require
more initial investment, but can have a quick payback
period.
Heated Swimming Pools
A plastic cover, which is required
by the Georgia Commercial Energy Code (ASHRAE 90.1) for
all heated pools, could save 50% on water heating costs.
A cover can reduce nighttime evaporation and heat loss
from 45° F to 1-2° F. Backflushing with a traditional
filter uses from 180 to 250 gallons of water. Investigate
installing water-conserving filters that decrease the amount
of backflushing. Since pool water temperature is only 70-80° F,
solar water heating is often economically attractive.
Cooling Towers
Cooling towers use water to remove
waste heat from heat generating equipment in commercial
and industrial applications. Cooling towers reject heat
to the outside air from the water loop through evaporative
cooling, reducing the temperature of the circulating water.
This water is then returned to the heat-producing equipment
to repeat the cycle. While water loss through evaporation
is a necessary part of cooling tower operation, excessive
water loss can occur if the cooling tower is not properly
maintained.
Two common opportunities for water
conservation in cooling towers are to reduce drift and
blowdown losses. Drift refers to water that does not evaporate,
but is lost from a cooling tower in droplets carried away
in the air flow. Baffles or drift eliminators can be installed
to reduce excessive drift. Blowdown refers to the intentional
draining of a portion of the cooling tower water to reduce
buildup of dissolved solids or other contaminants. Proper
water treatment can minimize the need for blowdown. Cost
savings can sometimes be achieved by installing a separate
meter on the cooling tower make-up water line to reduce
sewer charges (water that evaporates from a cooling tower
does not flow directly into the sewer system). Check with
your water company to see if a sewer credit for cooling
tower make-up water is offered.
Laundry
Hotels, hospitals, and other facilities
that deal with laundry can save water with modern systems.
Both horizontal and newer top loading clothes washers use
two-thirds less water than conventional washing machines.
Reducing the amount of water needed also means decreasing
the energy required to heat laundry water. Modern laundry
detergents work effectively in cold water, eliminating
the need for large amounts of heated water.
Ozone Laundry System
Injecting ozone into a washing
machine’s source water is a new technique that
saves water and energy. Ozonated water is a natural
bleach and an effective oxidizer that can break
down dirt and oils. Using ozone reduces the detergent
required and can eliminate the need for peroxide
or chlorine bleach. Ozone washers typically operate
better at temperatures in the range of 60-100° F
rather than at typical temperatures of 160-175° F.
These systems are appropriate for the health care
industry, hospitality industry, and other industrial
laundry services. An ozone laundry system can easily
be combined with a water recovery system and can
recycle at least 60% of the wastewater on its own
by incorporating a filtration system.
Example: Magnolia Manor Nursing
Home. This system, installed in 1996 in Americus,
Georgia, is comprised of two 250-lb. washers directly
injected with ozone that operate 5½ hours per day.
It uses a 3-stage filtration system for water recovery.
A month-long study in 1999 revealed average daily
water savings of 67% or 2,345 gallons.
Reduce Outdoor Potable Water Use
If the metro Atlanta region reused
10% of its presently treated wastewater, the region could
serve an additional 400,000 people without increasing wastewater
discharge.
This reduction can be accomplished
during design by using water efficient landscaping, native
plants, mulch, and other relevant xeriscaping techniques.
Capturing rainwater for irrigation
conserves water and reduces stormwater runoff. Rainwater
catchment systems require adding leaf screens to the existing
gutters and directing the water to storage barrels or a
cistern. The water is fed by gravity or pumped, in turn,
keeping the landscape healthy. If the harvested rainwater
is not used for irrigation, it must be purified and filtered.
Proper drainage should be provided in case the temperature
falls below freezing. Installation costs for a rainwater
collection system can range from $250 to $2000, depending
on a system’s size and complexity.
If allowable by the local building
code, graywater can be utilized. Graywater is commonly
defined as water drained from use in washing machines and
showers. The concept behind graywater irrigation is to
allow the soil to act as a filter. Graywater may require
some filtering and/or disinfecting with ultraviolet (UV)
light. After such treatment, graywater can be used for
below-ground irrigation just under a plant’s roots. Care
must be taken to ensure that graywater not be stored for
longer than 24 hours to prevent bacteria growth. To this
end, it is important to match the amount of graywater generated
to the amount necessary for landscaping needs.
Treat Wastewater On-site
Treating wastes close to their point
of origin is accomplished by constructed wetlands, sand
filters, or ecological wastewater treatments. Constructed
wetlands mimic the water purification capabilities of natural
wetland systems by minimizing water pollution prior to
its entry into streams and other waters. Presently, there
are 19 constructed wetlands in Georgia. Two are being created
in Clayton County with a total daily capacity of 34.5 million
gallons per day. It takes 3 days for water to move through
the wetland cells. Due to the cellular design, the systems
are not limited in scale and currently process 4,000 to
1,000,000 gallons per day. Costs are variable since this
technology is still in the demonstration phase.
Constructed wetlands cell system
used in Clayton County
The Living Machines®, a trademark
of Living Machines, Inc., is a form of ecological wastewater
treatment that mimics the efficient designs of nature.
Green (or garden) roof systems and
pervious pavement also provide accessible low-technology
solutions to reduce and treat stormwater run-off. These
approaches reduce impervious surfaces with benefits of
lessening heat island effects and charging the local water
table.
Reduce Indoor Potable Water Use
Following the strategies highlighted
in this water conservation checklist, such as regulating
water pressure and incorporating new technologies can reduce
water consumption. In addition, the use of low-flow fixtures
and leak monitoring devices combined with a focus on human
behavior can help promote water conservation and improve
water quality.
Water Conservation Points and Commercial Green
Building Rating Systems
The U.S. Green Building Council’s
Leadership in Energy and Environmental Design (LEED™) program
is used to score and quantify the sustainability of a commercial
construction project. The LEED™ program evaluates site,
energy, materials, and indoor environmental quality, as
well as water efficiency. LEED™ provides three credit areas
addressing water conservation: water efficient landscaping,
innovative wastewater treatment technologies, and water
use reduction. More information on the LEED™ program can
be found at their website: www.usgbc.org.
Water conservation strategies that
are a part of the LEED™ program have universal application
to many commercial situations. These strategies can be
used regardless of LEED™ participation.
Resources & Links:
“Facility Manager’s Guide to Water
Management”, and “Water Efficiency Manual for Commercial,
Industrial, and Institutional Facilities” are available
from the Rocky Mountain Institute: www.rmi.org/sitepages/pid276.asp
