In ‘The Century of the City’ there are many converging factors influencing the debate around urban energy consumption and efficiency including:

World population - Current world population in excess of 7 billion. Low forecast of 8 billion by 2050 with a high forecast of 10.5 billion, with a medium of 9.2 billion[2]

Urban population - It is estimated that over seventy percent of the world’s population will live in cities by 2050[3] This equates to 6.4 billion people living in cites by 2050.

Climate change – “In the decades to come, climate change may make hundreds of millions of urban residents – and in particular the poorest and most marginalized – increasingly vulnerable to floods, landslides, extreme weather events and other natural disasters. City dwellers may also face reduced access to fresh water as a result of drought or the encroachment of saltwater on drinking water supplies. These are the forecasts, based on the best available science. Yet none of these scenarios needs to occur, provided we act now with determination and solidarity.”[4]

Energy use in the urban context – According to some estimates cities account for 75 % of global green house gas emissions yet they only take up only 2 % cent of the Earth’s land mass. This is largely driven by the combustion of fossil fuels consumed in an array of urban processes ranging from residential, to industrial, through to transport etc.[5]

This energy consumption in urban areas is estimated to be approximately 80% of all commercial energy produced globally[6].


  1. Peirce, N.R., et al., Century of the city : no time to lose. 2008, New York: Rockefeller Foundation.
  2. World Watch Institute. U.N. Raises “Low” Population Projection for 2050. 2013  [cited 2013 Jan 13]; Available from:
  3. United Nations. World urbanization prospects the 2007 revision. 2006; Available from:
  4. Ban Ki-moon, Foreword, in Cities and climate change : global report on human settlements. 2011, UN-Habitat ; Earthscan: [Nairobi]; London; Washington, DC.
  5. United Nations Human Settlements, P., Cities and climate change : global report on human settlements, 2011. 2011, [Nairobi]; London; Washington, DC: UN-Habitat ; Earthscan.
  6. Jollands, N., S. Kenihan, and W. Wescott, Promoting Energy Efficiency Best Practice in Cities. 2008, IEA.