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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 160
6
IEQ
6.4
V
ENTILATION
I
EQ
10 B
ACKGROUND
V
ENTILATION
E
XCLUSIONS
Buildings not designed to utilise natural ventilation.
O
BJECTIVE
Ensure that normally occupied premises designed to utilise 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.
P
REREQUISITES
1 credit where it can be demonstrated that adequate ventilation can be
achieved by natural means.
A
SSESSMENT
The Client shall provide evidence in 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).
The minimum ventilation rate required to maintain known contaminants
below recognised limits can be calculated using recognised procedures,
for example, Appendix D of BS 5925 [1] or similar.
Ventilation performance may be simulated using wind tunnel tests,
computational fluid dynamics (CFD) or other appropriate modelling
techniques [2,3].
The modelling technique shall show a boundary layer as appropriate for
the site, and the model will include any significant buildings and site
obstructions within a distance of approximately 2 building heights. The
pressure data will be used with recognised calculation procedures (e.g.
BS 5925) to estimate flows through the habitable areas. Buoyancy or
turbulence driven flows need not be considered. Ventilation rates can be
predicted using either CFD or approaches that range in complexity from
simple single zone models to elaborate multi-zone models
[2].Principles
of model operation are discussed in the ASHRAE Handbook [4].
Alternatively, a suitable commissioning test may be performed, for
example a tracer gas decay test [5]. The test should be carried out in
representative units as defined above and performed under average wind
conditions with windows closed and purposely designed ventilators open.
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.
1
BS 5925:1991 (Inc. Amendment No 1), Code of Practice for Ventilation principles and designing for natural ventilation.
British Standards Institute, London. December 1995.
2
American Society for Testing Materials. ASTM E 2267-03. Specifying and Evaluating Performances of Single Family
Attached and detached Dwellings – Indoor Air Quality. 2003.
3
American Society of Heating, Refrigerating and Air Conditioning Engineers. ASHRAE Fundamentals Handbook Chapter
26. Atlanta 2001.
4
American Society of Heating, Refrigerating and Air Conditioning Engineers. ASHRAE Fundamentals Handbook Chapter
26. Atlanta 2001.
5
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.