BEAM Plus New Buildings

185 / 248

BEAM PLUS FOR NEW B UILDINGS INDOOR ENVIRONMENTAL QUALITY (IEQ)
V ERSION 1.2 IEQ 11 L OCALISED V ENTILATION
Copyright © 2012 BEAM Society Limited. All rights reserved.
Page 164
Where mechanical ventilation in form of an extractor fan is provided in
bathrooms and lavatories, care should be taken to ensure that plumbing
seals are intact and operate according to the design intent [ 6 ]. In
addition, consideration should be given to the quality and quantity of air
intake, air-flow path and fan capacity. The Environmental Health Team of
the World Health Organization (WHO) has advised that the optimum flow
rate for bathroom ventilation is 2 cfm/sq ft (10.2 l s-1 m -2). WHO is of the
view that a larger flow rate does not add much on the comfort side and
has the hidden risk of building up negative pressure in the room. It is
recommended to provide an opening to bathrooms and lavatories for air
relief, such as an undercut to the door or an opening with louvre at the
door or wall, in order to minimise the build-up of negative pressure if an
extractor fan is provided for ventilation.
UTILITY AND LAUNDRY
ROOMS
ASHRAE 62.2 [2] makes no requirement for mechanical ventilation
although it stipulates an opening not less than 4% of the room floor area
nor less than 0.15 m2. However it does stipulate that clothes dryers must
be directly exhausted to outside.
REFUSE AREAS Exhaust from refuse storage areas and material recovery centres (RS &
MRC) should follow the principles of PNAP No. APP-35 [7]. In the cases
where a centralised ventilation system is adopted, a single air purifier
may be installed prior to the air being exhausted to the atmosphere. If
there is no odour problem then a mechanical fan and filter can be used.
The main exhaust outlet for a centralised system should be located at
roof level away from other buildings. If the building is surrounded by taller
buildings then the air may be exhausted at the main RS & RMC location.
The noise level of the system should conform to the Technical
Memorandum published under the Noise Control Ordinance (Cap 400).
Fire dampers should be provided if the system has exhaust grilles and
ducting at each floor.
DOMESTIC GARAGES ASHRAE 62.2 states that for low rise residential buildings where air
handlers or return ducts are in an attached garage the ductwork should
be tested for air tightness. A ductwork air leakage test conforming to test
procedure DW 143 [8] or similar authority should be performed.
CHIMNEYS AND FLUES The siting and height of chimneys and flues should follow PNAP No.
APP-8 [9]. In particular, chimneys and flues should be situated so that
products of combustion cannot enter windows, ventilation openings,
supply air intakes.
6 Buildings Department. Practice Note for Authorized Persons, Registered Structural Engineers and Registered
Geotechnical Engineers, PNAP No. ADV-25 Extractor Fans in Bathrooms and Lavatories in Domestic Buildings.
7 Buildings Department. Practice Note for Authorized Persons, Registered Structural Engineers and Registered
Geotechnical Engineers, PNAP No. APP-35. Refuse Storage and Collection Building (Refuse Storage and Material
Recovery Chambers and Refuse Chutes) Regulations.
8 DW 143. A practical guide to Ductwork Leakage Testing. Heating and Ventilating Contractors Association. 1994.
9 Buildings Department. Practice Note for Authorized Persons, Registered Structural Engineers and Registered
Geotechnical Engineers, PNAP No. APP-8. Chimneys and Flues.