The effect of climate change and natural variability on wind loading values

Since 2006, a number of countries developed reports on climate change following the IPCC 4th assessment reports. For the Netherlands, the Royal Netherlands Meteorological Institute (KNMI) presented four new climate scenarios. Typically, climate change is described in terms of average changes, but much of the social and economic costs associated with climate change in the built environment will result from shifts in the frequency and severity of extreme events. In this study, the consequences of the climate change scenarios on the design wind speeds used in building regulations are discussed. Based on the best actual available knowledge of climate change models, the effect of climate change implies a change of -0.8% to +2.3% in the hourly mean wind speed with return period of 50 years, which is the basis of current building codes. To confirm the outcomes, further development of climate change scenarios is needed with more focus on extreme events with large return periods and small time scales. Natural variability of wind speed appears to have a great effect on wind trends for extreme wind velocities, and when adapting values for extreme climatic effects in building codes, both climate change effects and effects of natural variability should be considered. The analysis as presented for extreme wind speeds can be applied to other domains, such as thermal and precipitation where extreme values of climatic conditions define building design, and can therefore serve as general framework to assess extreme events. -------------------------------------------------------------------------------