Green Building and LEED Core Concepts Guide First Edition

Efficiency strategies, combined with monitoring that tracks water consumption and identifies problems,
can dramatically improve water conservation compared with comparable conventional buildings.
Many LEED-rated buildings reduce potable water usc by more than 50%, with direct benefits
for the bottom line and the environment.
Assessments and Measurements
• Design versus Baseline. The amount of water the design case conserves versus the baseline
case. AU LEED Water Efficiency credits use a baseline case against which the facility's design
case is compared. The baseline case represents the Energy Policy Act of 1992 (EPAct 1992)
flow and flush rates.
• Gallons per flush (gpf). The amount of water consumed by flush fixtures (water closets, or
toilets, and urinals). The baseline flush rate for water closets is 1.6 gpf. and for urinals, 1.0
gpf (EPAct 1992).
• Ga llons per minute (gpm). The amount of water consumed by flow fixtures (lavatory faucets,
showerheads, aerators, sprinkler heads).
• Irrigation efficiency. The percentage of water delivered by irrigation equipment that is actually
used for irrigation and does not evaporate, blow away, or fall on hardscape. For example.
overhead spray sprinklers have lower irrigation efficiencies (65%) than drip systems (90%).
INDOOR WATER
Indoor water use refers to the water that occupied buildings typically need
to operate on a day-to-day basiS-water for water closets, urinals, lavatories, showers,
and kitchen or break-room sinks. Indoor water usc reduction can be achieved by installing wateref~cicnt
fixtures, using nonpotable water for flush functions, and installing submeters to track and
log water use trends.
Low-flow fixtures use less water than specified in the EPAct
1992 requirements. Low-flow models are now available for
all indoor plumbing fIXtures. Projects can further reduce
their potable water consumption by deSigning and installing
plumbing systems that can use captured rainwater or
graywater In flush fixtures.
Submetering gives commercial building projects a way to monitor water use, track fixture performance,
and identify problems. With submeters, teams can better understand how much water is being
used for plumbing fixtures, as well as be alerted to any leaks or othcr problems that waste water.
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Green Building and LEED Core Concepts Guide