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BEAM P
LUS FOR
E
XISTING
B
UILDINGS
W
ATER
U
SE
(W
U
)
V
ERSION
1.2
W
U
4 W
ATER
R
ECYCLING
Copyright © 2012 BEAM Society Limited. All rights reserved.
Page 99
5
W
ATER
U
SE
5.1
W
ATER
C
ONSERVATION
W
U
4 W
ATER
R
ECYCLING
E
XCLUSIONS
None.
O
BJECTIVE
Encourage harvesting of rainwater and recycling of grey water in order to
reduce consumption of fresh water.
C
REDITS ATTAINABLE
1 + 1 BONUS
P
REREQUISITES
Compliance with the water quality standards appropriate to the use of the
recycled water.
C
REDIT REQUIREMENT
1 credit for harvesting rainwater and/or recycling greywater that leads to
a reduction of 5% or more in the consumption of fresh water.
1 BONUS credit where harvesting and/or recycling leads to a reduction
of 10% or more in the consumption of fresh water.
A
SSESSMENT
Harvested and/or recycled water shall satisfy the water quality
requirements for the intended reuse, e.g., cleaning, irrigation, use in heat
rejection systems, toilet flushing, etc.
The Client shall provide a detailed report on the system or systems
installed for the purpose of harvesting rainwater and/or recycled water,
the details of the expectations in respect of savings in the consumption
of fresh water The Client shall demonstrate that the treated grey water is
of a quality appropriate to the end use. The condensed water shall be
included in the calculation of recycled grey water.
Where it can be demonstrated that the savings in fresh water use is 5%
or more based on baseline building estimation the credit shall be
awarded. Where it can be demonstrated that the savings in fresh water
use is 10% or more the bonus credit shall be awarded.
B
ACKGROUND
Recycling of grey water not only helps to reduce the demand for potable
water supply, but also provides a reliable source in case of supply
interruptions. When properly done it is possible to reuse all wastewater
for various purposes. A grey water recycling system is one which collects
grey water (reclaimed condensate, etc) for treatment and distributes the
treated water to the points of use, such as for irrigation, cleaning, or for
toilet flushing where seawater supply is not available. Another potential
use of the recycled water is for evaporative heat rejection system in air
conditioning, which will provide an energy benefit and improves the cost-
effectiveness of water recycling.
The problem for Hong Kong’s high-rise dense built environments is that
the potential for collecting rainwater is limited. Yang et al [1] provide the
main parameters and their relationship to estimate the amount of
rainwater that may be collected on different roof areas and different sizes
of tanks, based on the amount of rainfall as recorded by the Hong Kong
Observatory.
Well-populated buildings not supplied with seawater for flushing would
be a good candidate from water recycling, otherwise reuse is likely to be
limited, depending on the extent of cleaning, irrigation and the types of
equipment used for cooling.
1
Yang H X, Chow W H, Burnett J. Water and Energy Conservation of Rainwater Collection Systems on Building Roofs.
Advances in Building Technology, Vol. 2. Elsevier. 2002. pp 1281-1288.