Skidmore, Owings & Merrill LLP, Chicago
Sunshading elements are becoming an increasingly important part of sustainable design for tall buildings. Additionally, double skin facades are an effective means of providing energy efficient thermal comfort by limiting the amount of radiated heat into buildings and generally provide good insulation for both hot and cold climates. It is often helpful to ventilate the cavity between the inner and outer skins.
Examples of sunshade elements and double skin facades will be presented. A general categorisation of different sunshading systems will also be presented. For each category, the effect of the sunshade system on the façade pressures will be discussed as well as the expected wind loads on the sunshade elements themselves.
The presentation will focus on the effect of the certain types of sunshade elements and double skin façade systems in reducing wind loads on the façade. Although some types of sunshades can increase the peak positive pressures at the top of the tower, it is the large negative peak pressures that often govern the design of the façades for tall buildings. The presentation will highlight the types of sunshade elements that tend to result in the most significant reductions in the wind loads on the façade glazing and which configurations of double skin facades are effective in reducing the large peak positive and negative pressures on the double skin system.
Wind noise generation by some sunshading elements can be problematic. Key considerations in the design of sunshades that help reduce the risk of wind noise will be presented, including a number of case studies.