Effects of wind and hail on building shading systems

For a new high-rise building in the Rhine Valley, which is affected by sun and the Foehn wind, a shading system was needed that could withstand both strong wind and hail peaks.

High-rise buildings place particularly high demands on shading systems. Due to their exposed position, they have to withstand much higher wind loads than those of standard detached houses. If the shading systems are not retracted in time, major hail damage can also occur.

An evaluation of the wind data from the last two years showed that gusts with wind speeds above 60 km/h occur on average 20 days per year at the site. Every two years, gust peaks of 126 to 144 km/h can even be expected. In terms of hail, the Rhine Valley is not one of the most endangered zones in Switzerland. Because blinds and awnings are often not retracted in time, a hailstorm nevertheless usually results in major damage.

Based on the given natural risks, we conducted a cost-benefit analysis for different shading products. There was a choice of tintable glass, blinds and awnings. The evaluation showed that the costs over the life of the building are lowest for electrically tintable glass.

We carry out calculations for hail and wind loads not only for shading systems, but generally for roof and façade components, sun blinds, skylight domes, green roofs or solar panel systems.



Figure: Recurrence values for the largest expected hailstone size over a reference area of 100 m² (LEHA) for the recurrence periods of 10 and 50 years (MeteoCH 2022)

Images: Damage to blinds caused by wind (left) and hail (right)


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