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BEAM PLUS FOR NEW B UILDINGS S ITE ASPECTS (S A)
V ERSION 1.2 SA 8 MICROCLIMATE A ROUND BUILDINGS
Copyright © 2012 BEAM Society Limited. All rights reserved.
Page 48
Beaufort Wind Effect
Number speed ms-1
0,1 0-1.5 No noticeable wind
2 1.6-3.3 Wind felt on face
3 3.4-5.4 Hair disturbed, clothing flaps
4 5.5-7.9 Raises dust, dry soil and loose paper, hair blown
5 8.0-10.7 Force felt on body, limit of agreeable wind
6 10.8-13.8 Umbrellas use difficult, difficult to walk steadily
7 13.9-17.1 Inconvenience felt when walking
8 17.2-20.7 Generally impedes progress
9 20.8-24.4 People blown over by gusts
For wind amplification, the value of 4m/s is based on Frank H. Durgin's
research [2]. This research shows that with 4m/s (actually 3.7 to 4.8m/s)
and k, the exponent from the Weibull distribution = 2, the probability of
the exceedance of a dangerous level will be within a reasonable range.
The use of non-reflective external surfaces contributes to localised
elevated temperatures created when solar heat gains are absorbed and
then radiated back to the surroundings. The effect may be local to
pedestrian and recreational areas, and contribute to urban heat islands.
As a result, local ambient and effective temperatures can rise by several
degrees or more when compared with more open and better ventilated
areas. Penalties include local discomfort, detrimental effects on site
vegetation and wildlife, etc. Elevated temperatures can be mitigated
through the choice of finishes on buildings and horizontal hard surfaces
that reflect heat, the application of shading or planting vegetation.
Microclimatic conditions of the site should be designed with a thorough
and balanced consideration of the wind, sunlight, temperature and air
quality.
To promote the awareness of project proponents in order to ensure that
air ventilation impacts are duly considered as one of the main criteria in
the planning and design process, HPLB has encouraged Air Ventilation
Assessment (AVA) to be included in the planning and design of the
projects. A framework for applying AVA is developed on the basis of the
‘Feasibility Study on Establishment of Air Ventilation Assessment’ [3]
completed and endorsed by the Committee on Planning and Land
Development in 2005. HPLB promulgated the Technical Circular (TC)
No. 1/06 on AVA in 2006.
AVA targets the projects that may have major impacts on the macro wind
environment. The Government will take the lead to apply AVA for all
major Government projects including public housing projects and
comprehensive redevelopment areas, while quasi-government
organisations and the private sector are encouraged to apply AVA to
their projects on a voluntary and need basis. The framework of AVA
would enable comparison of design options in external air ventilation
terms and identification of potential problem areas for design
improvements.
2 Pedestrian level wind criteria using the equivalent average - Frank H. Durgin 1997.
3 Advisory Council on the Environment- Feasibility Study for Establishment of Air Ventilation Assessment