Win the ‘Wind Speed’ with Beaufort’s Wind Scale

Win the ‘Wind Speed’ with Beaufort’s Wind Scale

Why does wind speed play a critical role in shaping pedestrians’ perception of wind comfort?

Figure 01: Yellow wind sock on a wooden post (Photo by Dlanor S. on Unsplash)

For cities, it is vital that pedestrians feel both thermally comfortable and safe while walking. The mechanical effects of wind on pedestrians are typically assessed using the Beaufort Wind Scale, an internationally recognized standard (see Table 1 below). Wind speeds measured at 10 m above ground level are approximately reduced to 75% at pedestrian head height (1.5 m), as noted by Bennett (2007) and Stathopoulos (2009).

Weighing 'Wind Distribution Pattern' for Building Design in Dhaka City

How Wind Speed and Wind Flow Direction May Influence Shading of the South and Southeast

I wish Dhaka City were windier! (Photo by Keenan Constance on Unsplash)

Neither Chicago nor Seoul, Dhaka rarely experiences the strong breezes typical of such windy cities. However, superimposing wind data on a windrose diagram shows that the Southern and Eastern fronts are not entirely calm. At least 68% of the annual breezes come from the South, East, and Southeast (see Fig. 1 below). In the diagram, the yellow-shaded area represents the combined percentage of wind flow in Dhaka City. Strategically placing openings on the South and Southeast sides would enhance natural ventilation in buildings. Nevertheless, due to Dhaka’s equatorial location, shading design is essential to modulate solar gains during the summer months.