Research shows that dual-flush toilets in non-residential settings are not using the partial-flush as anticipated.
Measures to improve water efficiency, including
limitations on full-flush volume for toilets and use of municipal reclaimed water
for irrigation, are being proposed for a green building standard.
189.1-2011,Standard for the Design of High-Performance, Green
Buildings Except Low-Rise Residential Buildings, provides a design
standard for those who strive for high performance buildings. It covers key
topical areas of site sustainability, water-use efficiency, energy efficiency,
indoor environmental quality and the building’s impact on the atmosphere,
materials and resources.
The changes regarding water are
proposed via addendum v, which is open for public review until Jan. 14, 2013.
To comment on the proposed changes or for more information, visit
The addendum would limit the
full-flush volume for all toilets to 1.28 gal per flush and limit kitchen
faucet capacity to 1.8 gpm. Research shows that dual-flush toilets in
non-residential settings are not used in the 2:1 full-flush to partial-flush
ratio as anticipated. Instead, the full-flush option is almost always employed.
“There is no evidence that the
dual-flush toilets use significantly less water than the full-flush in
commercial settings,”Thomas Pape, a member of the Standard
189.1 committee, said. “We have found that 90 percent of the flushes from dual
flush toilets are full flushes. Since many models of dual-flush toilets would
meet a maximum of 1.28 gal for the full flush, the maximum volume for
dual-flush toilets has been decreased to match the maximum volume for
The kitchen faucet maximum capacity
is being changed to reflect the current water efficiency standard of 1.8 gpm
established by various green codes.
Proposed addendum v also would set
limits on the use of municipal reclaimed water for irrigation. Municipal
reclaimed water is highly treated, usually to drinking water standards, and
often in short supply. Furthermore, the growing use of municipal reclaimed
water for groundwater recharge of potable water supplies increases its value.
“It is unreasonable to allow the
unfettered use of reclaimed water, considered a precious resource, as a means
to save energy when there are more viable alternatives,” Pape said. “Therefore,
the use of municipal reclaimed water would be prohibited for roof-cooling
applications and for permanent irrigation of vegetated roofs using either
in-ground or above-ground irrigation systems. There are many other alternative
water sources that can be used for this puprpose, including graywater,
condensate recovery, rainwater and cooling tower discharge.”
Its temporary use in above-ground
irrigation systems is allowed, however, during the vegetation establishment
period required for vegetated roofs.
For more information on the other
addendums for public review, visit
ASHRAE proposes green building standard to improve water efficiency
December 6, 2012