Increasing urbanisation is expected to result in a significant share of the world population living in a built environment that, unless sustainable construction materials are used, will lead to a considerable carbon footprint. The development and more widespread use of limestone calcined clay cements such as LC3 and LC2 is not only expected to reduce the construction footprint but also offer a business opportunity. By Dr Debojyoti Basuroy, TARA Applied Research Centre (TARC), India