This design of a new facade to completely re-clad an existing highrise addresses both Federal blast-resistance guidelines and dramatically improves thermal performance. This project in Cleveland is the first known highrise retrofit double wall application. The existing 1967 stainless steel and glass skin was stabilized as the inner component wall and expressed as the visible structure of the newly applied transparent skin. This strategy assisted a design methodology of integration and adaption of changing criteria and needs to an existing building. Design sensitivity to the original design aesthetic was a mandate throughout the extensive design process. This project is a unique case study in a substantial renovation of a fully-occupied highrise building. The double wall configuration limited disruptions during construction by avoiding total tenant relocation for high security tenants.
Double wall design is extraordinarily complicated, particularly with an existing façade. The prediction of the impact of the new cladding must be analyzed integrally with the internal environmental systems. Standard THERM modeling, which analyzes two-dimensional heat-transfer effects in building components, is insufficient, and more advanced methods such as computational fluid dynamic analysis must be undertaken. This drives the design methodology for material selections and system approaches such as venting and supplemental conditioning. Climatic considerations determine the appropriate type of double wall system, as there are a wide range – each with their own particular strengths and weaknesses. Consideration of access for cleaning and maintenance of double wall systems is also critical from project inception.