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BEAM P
LUS FOR
E
XISTING
B
UILDINGS
A
PPENDICES
V
ERSION
1.2
8.5 A
SSUMPTIONS AND
B
ASELINES FOR
W
ATER
C
ONSUMPTION
Copyright © 2012 BEAM Society Limited. All rights reserved.
A - 14
8.5
A
SSUMPTIONS AND
B
ASELINES FOR
W
ATER
C
ONSUMPTION
The following details the default assumptions for the calculation of the
reduction in water use of the project building when compared with an
equivalent base line space.
N
UMBER OF
W
ORKING
OR
O
PERATIONAL
D
AYS
The number of operational days per annum (Nop) should be obtained
from the design brief or Owner’s Project Requirement (OPR) document.
The number of non-operational days is equal to 365-Nop.
The same values of operational and non-operational days will be used
for both the project space and the base line space.
O
CCUPANCY
C
ONSIDERATIONS
The number of occupants shall be taken from the design brief, or owner’s
project requirements (OPR). If this data is not obtainable then, in the
absence of any other data, the occupant space allowance should be
taken as 9 m
2
/person. [1]
The
male:femaleratio should be determined from the design brief or
OPR If the data is not available then the default assumptions are as
follows:
In offices, the male to female occupancy ratio is 1:1 [2]
In public places, the male to female occupancy ratio is 1:1.25 [2]
The same occupancy load shall apply to the project space and the
baseline space.
WC W
ATER
U
SE
The base line building will have a single flush WC (i.e. no low flush
option) with a flushing volume of 7.5 litres per flush. [3] The water closet,
cistern and flushing fitting shall be of compatible types.
For non-residential,
Males use the WC once per day. If a dual flush system is installed in the
project space, it is assumed that the WC will be flushed using the high
flush volume.
Females use the WC five (5) times per day. If a dual flush system is
installed in the project space, it is assumed that the average flush
volume is equal to the average of one full flush and four low volume
flushes for both males and females.
For residential,
Residents use the WC five (5) times per day. If a dual flush system is
installed in the project space, it is assumed that the average flush
volume is equal to the average of one full flush and four low volume
flushes for both males and females.
The flow rate of the water appliance should be read as an absolute figure
irrespective of the working pressure in predicting the water consumption.
1
Hong Kong Buildings Department (1996), Code of Practice for the Provision of Means of Escape in Case of Fire, Building
Authority, Hong Kong.
2
Buildings Department. Practice Note for Authorized Persons, Registered Structural Engineers and Registered
Geotechnical Engineers. PNAP No. ADV-28 Provision of Sanitary Fitments in Offices, Shopping Arcades and Department
Store, Places of Public Entertainment and Cinemas.
http://www.bd.gov.hk/english/documents/pnap/ADV/ADV028.pdf3
Buildings Department. Practice Note for Authorized Persons, Registered Structural Engineers and Registered
Geotechnical Engineers. PNAP No. APP-99 Flushing Volume for Flushing Cisterns.
http://www.bd.gov.hk/english/documents/pnap/APP/APP099.pdf