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BEAM P
LUS FOR
E
XISTING
B
UILDINGS
I
NDOOR
E
NVIRONMENTAL
Q
UALITY
(I
EQ
)
V
ERSION
1.2
I
EQ
11 B
ACKGROUND
V
ENTILATION
Copyright © 2012 BEAM Society Limited. All rights reserved.
Page 126
6
IEQ
6.4
V
ENTILATION
I
EQ
11 B
ACKGROUND
V
ENTILATION
E
XCLUSIONS
Buildings not designed to utilize natural ventilation.
O
BJECTIVE
Ensure that normally occupied premises designed to utilize natural
ventilation are provided with a minimum of background ventilation to
control indoor air pollutants.
C
REDITS ATTAINABLE
1
P
REREQUISITES
Compliance with the Building (Planning) Regulations (B(P)Reg.) 30, 31
and 32.
C
REDIT REQUIREMENT
1 credit where it can be demonstrated that adequate ventilation is
achieved by natural means.
A
SSESSMENT
The Client shall provide evidence in the form of a report by a suitably
qualified person stating that appropriate analysis or measurements have
been undertaken to verify the adequacy of background ventilation
(minimum air change rate). Compliance should be demonstrated using
any suitably verified or scientifically validated method, for example a
tracer gas decay test [1].
Where it can be demonstrated that background ventilation meets ACH of
2.0 that is of a higher level (ACH of 1.5) as prescribed by the Building
Authority (BA), the credit can be awarded.
B
ACKGROUND
Background ventilation is a combination of uncontrolled air infiltration and
ventilation through purposely designed vents. Purpose designed
ventilation is preferable to relying on uncontrolled infiltration. BEAM
seeks to encourage designs that provide for adequate background
ventilation by natural means.
Background ventilation is intended to dilute the unavoidable contaminant
emissions from people and materials (e.g. radon) and for control of
internal moisture levels due to occupant activities in order to minimize
risk of mould growth. During periods when windows and other openings
are closed it is possible for indoor radon levels to rise above the criteria
recommended by the Environmental Protection Department [2]. Local
research on residential buildings suggests that 0.5 to 1 ACH would be
sufficient to maintain radon below the target level 3.
1
ASTM E 741-00. Standard Test Method for Determining Air Change in a Single Zone by means of a Tracer Gas Dilution.
American Society for Testing Materials. Pasadena USA. 2000.
2
Indoor Air Quality Management Group. A Guide on Indoor Air Quality Certification Scheme for Offices and Public Places.
http://www.iaq.gov.hk/cert/doc/CertGuide-eng.pdf3
Chao C Y H, Tung T C W, Burnett J. Influence of ventilation on indoor radon level. Building and Environment. Vol. 32, No.
6. pp 527-534. 1997.