World Cities Report 2022: Envisaging the Future of Cities — Housing Materials and Sustainability
About this book
The United Nations Human Settlements Programme (UN-Habitat) World Cities Report 2022: Envisaging the Future of Cities — Housing Materials and the Circular Economy examines how cities can navigate the twin challenges of rapid urbanisation and the climate emergency to build sustainable, inclusive urban futures. Published as part of UN-Habitat's biennial flagship series, the 2022 edition focuses particularly on the material dimension of urbanisation and the transformative potential of circular economy approaches to urban development. The report begins with current urbanisation projections: by 2050, approximately 68% of the world's population — some 6.7 billion people — will live in urban areas, requiring the construction of an estimated 2.5 billion additional housing units and enormous expansion of urban infrastructure.
The environmental implications are examined: the construction, operation, and eventual demolition of urban buildings currently consume approximately 50% of all raw materials extracted globally and generate 35-40% of municipal solid waste in high-income countries. The housing materials analysis is a distinctive feature of this edition. The report examines the lifecycle environmental impacts of dominant housing construction systems — reinforced concrete frame, structural steel, cross-laminated timber, masonry, and vernacular earth-based construction — across different income contexts.
It documents the growing interest in alternative low-carbon materials (bamboo, engineered timber, recycled aggregates, geopolymer concrete) as cities seek to reduce the embodied carbon intensity of their growth. The circular economy framework is applied to urban development through four strategic areas: design for adaptability and disassembly (extending building lifespans through flexible layouts and demountable components), material passports and urban mining (tracking and recovering valuable materials at building end-of-life), industrial symbiosis in construction supply chains (reusing waste streams from one sector as inputs for another), and sharing models for space and infrastructure (co-working, co-housing, shared mobility that reduce total material demand). Housing access and affordability are addressed through analyses of land value capture, social housing provision, and community land trusts as mechanisms for ensuring that circular economy transitions benefit vulnerable urban populations rather than simply unlocking new profit opportunities for real estate developers.
The report concludes with policy recommendations for national and city governments, emphasising procurement standards for recycled content, building codes that permit innovative low-carbon materials, and urban planning frameworks that treat existing buildings as material banks.