wind conditions
location data
sunpath 캜 MONTHLY DIURNAL AVERAGES - Hong Kong, China
W/m?
40
1.0k
30
0.8k
20
0.6k
10
0.4k
0
0.2k
-10
0.0k Jan
Although Hong Kong is located on the Northern Hemisphere, just South of the Tropic of Cancer, she has a humid subtropical climate (Köppen Cwa).
Summer is hot and humid with occasional showers and thunderstorms, and warm air coming from the southwest. Typhoons are most likely to occur during Summer. Thus, for outdoor pedestrain comfort, wind shelters should be provided to prevent hot air from SW during summer months and cold breeze from NE in winter months.
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
캜 DAILY CONDITIONS - 1st January (1)
W/m?
40
1.0k
30
0.8k
20
0.6k
10
0.4k
0
0.2k
Majority of the year, the sunpath is predominantly shone on South of Hong Kong, thus it would be wise to provide more shading there. This also means that the North facade would be shaded and this permanent shading could be exploited by providing minimal glazing to expose views of the surroundings. . There is also a high component of direct solar radiation as compared to diffused radiation in general. However, solar load peaks from October to December, indicating that shading from direct sunlight from the South during this period is necessary. LEGEND Comfort: Thermal Neutrality Temperature Rel.Humidity Wind Speed
Direct Solar Diffuse Solar Cloud Cover
-10
2
4
6
8
10
12
14
16
18
20
22
24
0.0k
DESIGN STRATEGIES typhoon wind loading
sun-shading
sunscoop
shortcomings
Since Hong Kong is susceptible to strong winds and typhoon during Summer, it is crucial that typhoon wind loading is taken into consideration. Architect Norman Foster, together with Arup have incorporated cross-bracing to resist wind loading. Such bracing can also resist against earthquakes and tsunamis as well. Reinforced concrete floors also acts as a sheer plane, reducing axonal rotation of the building. During the wind tunnel testing, this design was able to withstand tsunamis of 30 hours at 30 knots and severe winds as well. Thus, in the final design, The facades were influenced by the U shape structure created by cross bracing on the East, West and South facades excluding the north. This provides a floor to sky glazed surface on the North. The East and West contain the main structural masts. This has a bold and powerful external representation directing the eye upwards.
Given that the sunpath is predominantly on the South, extensive shading would be needed on the South facade. As seen from the figure above, the South facade is completely shaded while the East and West facades have adjustable shading devices which would allow natural diffused light to penetrate into the building. And since the North facade is predominantly in the shade, shading could be minimal to exploit framing of the surrounding views.
Exploiting the relatively sunny conditions of Hong Kong and in an attempt to improve energy efficiency, the sunscoop was designed to control the use of solar radiation. The system consisted of exterior and interior sun scoops. During the day, these sun scoops will illuminate the building including the vertical atrium sun scoop, allowing for natural light to pass through the building from the East to West throughout the day. Mirror bays within the sun scoop can be adjusted through a mechanical computing system. At night, the interior sun scoops illuminate the space using artificial light, allowing for the same process of illumination, using mirrors, even without the presence of direct sunlight. This is an example of active and passive mechanism working hand-in-hand
The relative humidity levels of Hong Kong are rather high, however the design of HSBC has not taken this into much consideration. Perhaps the use of indoor air-conditioning could act as a dehumidifier to improve humidity levels. However, even though the air-conditioning systems of HSBC runs on seawater, it may not be totally energy or cost efficient (for that matter) to solely depend on active mechanisms to reduce humidity levels. Perhaps, natural ventilation in the form of cross ventilation could be implemented, especially so when wind speeds are generally strong enough to ventilate the building. If too strong, wind shields could be used to regulate the wind speeds as well. In addition, there is a lack of greenery around the building. Greenery is capable of reducing the ambient temperature via evapo-transpiration thus cooling the building down and allowing less reliance on mechanical cooling. While the skygardens which were integral in Foster’s initial scheme were not implemented, they could fortunately still be installed easily.
HSBC, HONG KONG Rachel Yang Wenling | A0071107U
architect | sir norman foster location | 22˚16’48” N114 ˚9’34”E