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BEAM P
LUS FOR
N
EW
B
UILDINGS
I
NDOOR
E
NVIRONMENTAL
Q
UALITY
(I
EQ
)
V
ERSION
1.2
I
EQ
10 B
ACKGROUND
V
ENTILATION
Copyright © 2012 BEAM Society Limited. All rights reserved.
Page 161
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
encourages 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 minimise
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 [6]. Local
research on residential buildings suggests that 0.5 to 1 ACH would be
sufficient to maintain radon below the target level.
For domestic buildings the Building Authority (BA) is prepared to accept
the following alternative performance standards on the provision of
natural ventilation in habitable rooms [7]:
Room of domestic
building
Air Change per Hour (ACH)
Habitable Room
1.5 (natural means)
Kitchen
1.5 (natural means) plus 5 (mechanical
means)
6
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.pdf7
Buildings Department. Practice Note for Authorized Persons, Registered Structural Engineers and Registered
Geotechnical Engineers, PNAP No. APP-130 Lighting and Ventilation Requirements – Performance-based Approach.
http://www.bd.gov.hk/english/documents/pnap/APP/APP130.pdf