NOT FOR DISTRIBUTION - DRAFT VERSION, MARCH 2017 – ELITH WEB word count: 6700 + biblio 960 - from NEW DRAFT 2016 sent to Dale, Ali Previous title: URBAN DISTRICT ENERGY SYSTEMS: POTENTIAL AND CONTRADICTIONS DISTRICT COOLING – A KEY SOLUTION FOR HOT CLIMATE CITIES Chris Butters, Warwick University, UK 1. Introduction Cooling, in the rapidly growing cities of hot climates, is a major source of energy use and greenhouse gas emissions. In addition these cities are experiencing growing heat island effects, urban living resulting in deteriorating environments and indeed rising heat-related mortality. This chapter addresses sustainable energy solutions at neighbourhood and urban scale, principally but not uniquely for cooling in hot climate cities. This has implications for energy policy in many contexts. An almost universal trend in developing country cities is towards air conditioning (AC) in individual buildings and rooms. Each one exhausts heat to the outdoors, hence simply heating up the urban environment even more. This urban heat island effect (UHIE) is expected to lead to increasing discomfort, and ill health as well as rising energy needs – due both to urbanisation itself and to warming climates. Thus, ironically, cooling is itself (in addition to heat from vehicles) one of the major causes of heat in the city. Typically, heat from vehicles accounts for between 20-30% of the anthropogenic sources of heat in large cities but energy use in buildings accounts for 60-75 (1a). In all but the poorest hot climate cities (where people cannot afford air conditioning), cooling alone makes up around half of this. In addition to exacerbating UHI, individual air conditioning units are inefficient, not always healthy, and expensive to run, usually requiring high quality electrical energy. Urban energy solutions can be far better solved at a larger scale than by addressing individual buildings. Technical efficiencies can be considerably higher; and they offer other advantages related to energy sources, delivery and management. Importantly, district energy solutions also offer one of the only ways to counteract the heat island effect. Whilst district heating systems (DHS) have been spreading for some years, district cooling (DC) is less well known. There is now a major effort to spread awareness of these solutions, not least in Asia. Large scale systems of this kind have existed for some years in cities in both hot-dry and in hot-humid climates. Our selected focus country, Malaysia, is a leading example. We briefly present principles, examples and challenges, adding (?nb?) a special note on low-income contexts. We also highlight a little discussed conflict between the level of individual buildings versus that of urban energy planning. Although the building sector accounts for 30-40% of global energy use and climate emissions, much policy focus today is still directed towards individual buildings. Individual buildings may have a lifespan of well under 100 years and can often be modified to higher energy efficiency (EE) standards during their lifetime; but the overall urban layouts, and energy systems, are on the contrary extremely onerous to modify and likely to be fixed for centuries. This underlines the importance of addressing the urban level. Further, our goals of mitigating energy use and climate emissions must go hand in hand with providing comfortable living environments, not least for the large low-income populations of developing countries. Although individual technologies will improve, the only long-term, systemic solution to UHI is to address energy solutions at the urban scale. Essentially, this means removing the sources of heat from the city. This is what DC systems do. They offer the unique feature of reducing the urban heat island effect, thus impacting positively on environment as well as on comfort and public health. In this book we underline the importance of a holistic approach and the interrelationship between the three levels of micro, meso and macro environments. But which level should be prioritised, and under what conditions? This is discussed below since it poses questions for sustainable urban planning and energy policy.