1. The role of cold in urban environments

The International Institute of Refrigeration (IFF) estimates that the total number of refrigeration, air-conditioning and heat pump systems in operation worldwide today is around 3 billion units.

Still according to the IFF, 20% of this worldwide installed base, i.e. some 600 million units, is dedicated exclusively to stationary air conditioning systems used for human comfort, industrial processes and the healthcare sector.

The use of air conditioning has grown considerably over the last 70 years, thanks to technological advances and the economic development of many countries, particularly in the world's warmer regions.

The vast majority of air-conditioning systems are installed in cities. In China, for example, the ratio of air-conditioning systems installed in urban households rose from 1% in 1999 to 100% in 2009....