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A Benchmark for Zero Water Use in Commercial Building:
Melbourne's
60L
by Doug Pushard
 As
the trend toward environmental awareness continues in both the
private and public sector, more and more zero and low-impact buildings
are being designed and built. Most of these projects are focused
primarily on electrical energy usage, with water use as an afterthought.
This is especially so for commercial buildings - with one noteable
exception: the 60L office building in Melbourne, Australia,
which was designed with water efficiency as an integral part of
the design.
"World-class
low-water usage was the goal", said Alistair Mailer, Project
Manager for the Green Building Partnership. The building
was completed in 2002 and houses 15 tenants and over 200 occupants.
"We try very hard to educate our tenants about the 'green' aspects
of the building and its environmental credentials. It is surprising
how many people, once they enter the building, immediately appreciate
many of its 'green' aspects.  Our
water tanks and water treatment are highly visible on the ground
floor of the building - a conscious effort was made to ensure
that water was truly an icon issue for the building."
But
this is not a typical office building. The building relies
almost exclusively on rainwater; including for drinking water.
 The
rain is collected from the roof, stored in two tanks on
the ground floor, filtered, and then sterilized prior to use by
tenants in taps and showers. Rainfall from the roof is harvested,
then transferred into the holding tanks via a 'Syfonic' system,
which uses gravity to create a syphon effect, which means water
transfer is faster and pipe diameter can be greatly reduced.
More
than 132,000 gallons (500 kiloliters) of rainwater can be collected
in an average year. Consequently, the building is almost totally
self-sufficient. The only major system not planned to use the
rainwater was the fire sprinkler system, which is mandated to
be connected to the municipal water system.
Melbourne,
Australia is blessed with a good supply of rain - about 25.8 inches
(657 mm) annually, and gets 8-10 days of rain most months. The
water storage tanks, usually one of the most expensive components
of the system, did not have to be super-sized to store water for
extended dry periods, which Melbourne sometimes experiences, because
water efficiency was planned into the building.
| Key
System Components
›
10,000 square foot (1,000
square.meter) roof area
› 2 - 2,600 gallon (10,000 liter)
tanks
› 6 - .8 gallon (3 liter) toilets
› 6 - waterless urinals
› 4 - low-flow shower heads
› 4 - Grundfos vertical multistage
pumps, one for drinking water
and one for reclaimed water and
a backup for each system
› 1 - 4-stage treatment system
including UV lamp for drinking
water
› 1 - 3-stage filtration system
including UV lamp for
reclaimed water
› 1450 square foot (135 sq. meter)
roof garden
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The
60L building includes waterless urinals and low-flow shower heads
and toilets, greatly reducing the overall water requirements.
The storage tanks are connected to a 4-stage treatment system
consisting of 3 filters and a UV sterilization lamp and supply
potable water to the showers, sinks, and the kitchen (see the
sidebar and related topics for more information on the exact system
components).
Used
water from the above components is then fed into a combined grey
and blackwater biological sewage treatment system. The treated
'reclaim' water is further filtered and UV sterilised for use
in toilets, the roof garden, and the water feature. Any excess
'reclaim' water overflows into the city sewer system.
"The
objective of the building was to provide an example of a commercially
viable, significantly more environmentally sustainable commercial
office development, to help bring about a change in the commercial
building sector", explains Alistair. "Water was considered
an 'icon' issue for the building". Compared to a commercial
building of equivalent size, the 60L building consumes about 50%
less water due to low-flow toilets, waterless urinals, and low-flow
shower heads. These low-use water fixtures also greatly reduce
the required tank size, providing a cheaper overall water catchment
system and, as importantly, a space savings.
Over
the last year, the building achieved an 80% water savings without
the reclaimed sewage treatment system working. It is expected
that with harvesting rainwater and with the reclaimed water system
fully functioning, this integrated system should continually supply
upto 95% of the buildings needs depending on rainfall patterns.
With larger tanks, an even higher percentage would have been possible,
since during prolonged rains, the existing storage tanks occasionally
overflow.
Most
importantly, this building proves that today, it is almost
possible to build zero water-use commercial buildings. It
simply requires advanced planning and the desire to build green!
Water
rates have been slowly increasing in Melbourne, as the Victoria
State Government pursues a dual policy of encouraging conservation
and increasing the water prices. As rates continue to increase
and builders become more aware of buildings like the 60L, more
sustainable office buildings are sure to follow. Learn
more about 60L >>
Related:
Article:
Australia
Using Less Water
Schematic of the 60L potable
water system (PDF)
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