Highrise Greenery: Ancient Invention with New Lease of Life

Abstract

Many cities especially compact ones are beset by urban heat island effect compounded by climate change and poor environmental quality. Urban green infrastructure can provide promising relief, but its implementation in dense cities is constrained by inadequate solution space. Departing from conventional thinking, greenroofs offer an innovative alternative of converting the negative amenity of barren roofs to pleasant greenery plus handsome bonus of multiple ecosystem services. The ancient origin of greenroofs is traced to the pragmatic need to build primitive shelters in harsh climate. Gradual refinement of the precursor has allowed development of a cultural invention. Despite continued installation in rural areas, its adoption in cities remained scanty in historical times. The notable classical exemplars in pre-industrial and industrial periods are assessed as pioneers. With fortuitous combination of factors, the idea was revived in Germany from the 1960s, spearheaded by scientific research and technological innovations. The new materials and designs, in conjunction with enabling public policies, have pump-primed the modern greenroof movement which subsequently spread to other European countries and then worldwide. The critical technological advances and the directions for further improvements are critically evaluated. The need to deepen understanding and enhance the key functions of cooling, warming and stormwater management is highlighted. Some inspiring recent projects are surveyed with respect to their outstanding innovative elements. Future developments could focus on tailor-made, cost-effective and environmentally-friendly dimensions.