ITU‐T's Technical Reports and Specifications 459 1 Intelligent sustainable buildings 1.1 Introduction Cities cannot become smart and sustainable unless the issue of the built environment and in particular buildings are addressed. On a global basis, buildings are responsible for 40% of global annual energy consumption and up to 30% of all global energy‐related greenhouse gas (GHG) emissions. Also on a global basis, the building sector is responsible for one‐third of humanity’s resource consumption, including 12% of all fresh‐water use, and produces up to 40% of our solid waste. Source (UN‐Habitat 2013). In order to address the issue of climate change through the reduction of GHG emission the impact of buildings must be reduced. It is therefore important for buildings to become more intelligent and more sustainable to reduce this environmental impact dramatically. The concept of a \"smart\" or \"intelligent\" building may seem to be an oxymoron. Intelligence is normally indicative of a human (or animal) attribute in which individuals are capable of making interpretations, deductions or inductions, related to observations and to stimuli. Some great individuals, such as Einstein, have been described as extraordinarily \"smart\" or intelligent\" and so it may seem that making these associations with inanimate objects such as buildings is, at first glance, an inappropriate association. The concept of \"intelligent buildings\" has been around for a number of years and has relied on the ability of individual systems within the buildings to communicate, to integrate and to perform in a manner allowing for numerous, complex, controls to generate a much‐enhanced response to many kinds of stimuli. Thus, the argument of intelligence can reasonably be associated with the ability of these buildings to function in an enhanced manner yielding many benefits for the occupants, the operators and the owners. This report will provide a number of examples of \"intelligent buildings\", while describing the benefits and efficiencies generated by such integration. Definitions of intelligent buildings have been proposed by different user groups and have also evolved during the last few years. Some view the ultimate benefits of intelligence to be the provision of a more efficient and effective working environment for the occupants, while others define such intelligence as providing greater economics for the building operators and yet some others conclude that automated responses, in particular to security and emergency situations, are of particular importance. The following definitions for intelligent buildings should be considered: The use of integrated technological building systems, communications and controls to create a building and its infrastructure which provides the owner, operator and occupant with an environment which is flexible, effective, comfortable and secure; Use of technology and process to create a building that is safer and more productive for its occupants and more operationally efficient for its owners; A building in which, those responsible for its operation, those benefiting from its operation and those ultimately responsible for the safety of all its occupants can share a view, and a vision of the building status at all times.