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Lily Riahi
Sustainable Energy in Cities Advisor, UN Environment Programme

For many cities worldwide delivering sustainable heating and cooling means the development of modern district energy systems. These consist of networks of insulated pipes running under city streets, pumping hot or cold water to multiple buildings in a district, neighborhood or city. Modern district energy systems can reduce primary energy consumption for heating and cooling of urban buildings by half. This dramatic reduction in energy consumption delivers the diverse benefits that progressive cities are committed to providing for their citizens, such as clean air and local jobs.

The energy sources needed to heat or cool the water pumped around modern district energy systems are often extremely energy efficient and renewable. These energy sources are often local and otherwise cannot be used, such as waste heat from industry or power stations, or excess heat in the sewage system. Many cities also connect large renewable sources such as geothermal, solar thermal or free cooling from lakes, rivers or seas. The multiple benefits of using such energy sources include reduced fossil fuel consumption, cleaner air, steady and reduced heating and cooling prices, and increased energy security by reducing blackouts. Paris is one example of what can be achieved. The City of Light has developed one of Europe’s largest district cooling networks, using the cool water from the river Seine to provide cooling to offices, shops, hotels and museums. This district cooling network uses half the energy for cooling that individual buildings would otherwise use and produces 50 percent less CO2 emissions and cuts refrigerant use by 90 percent. Paris also has a city-wide district heating network using geothermal, biomass and excess heat from power plants and waste incinerators to heat the equivalent of 500,000 households. By 2020, the district heating network will use 60 percent renewable or recovered energy.

This is just one of the forty-five city examples from the UN Environment Programme’s flagship report District Energy in Cities – Unlocking the Potential of Energy Efficiency and Renewable Energy, which sets out the best practice technology applications, policy and business models needed for cities to implement sustainable heating and cooling. Through 150 interviews across 45 low-carbon cities, district energy systems emerged as a best practice approach in scaling up renewable energy and energy efficiency. Cities worldwide, in countries as diverse as China, Canada, the United States, South Korea, Singapore, Colombia, Russia, the European Union, Saudi Arabia, the United Arab Emirates and Japan are using modern district energy to reduce energy consumption for heating and cooling of urban buildings by 30 – 50 percent and to achieve ambitious targets for energy efficiency, renewable energy, CO2 and clean air.

Switching to modern district energy requires innovative local planning that integrates energy and land-use, and coordination across multiple city sectors such as energy, transport, housing, waste collection and wastewater treatment. Because it’s new to many cities it takes time and many local governments worldwide do not have the capacity, accounting tools, or a clear mandate from their national governments to intervene in the sector. In response to these barriers UN Environment’s District Energy in Cities Initiative is supporting local and national governments worldwide to strengthen policy and planning frameworks that will enable accelerated investment in modern district energy systems. The Initiative has built a partnership of almost 40 organizations including technology providers, utilities, financial institutions, academia, international organizations, city networks, NGOs and champion cities to raise awareness and transfer policy best practice worldwide in countries such as India, China, Serbia and Chile. One example of the Initiative’s work is an ongoing collaboration with the government of Italy to support Marrakech and the national government of Morocco to adopt and scale-up modern district cooling systems. This approach to cooling buildings can contribute significantly to Morocco’s ambitious energy efficiency targets, and showcase the viability of the technology to other countries in the region.

The District Energy in Cities Initiative is a multi-stakeholder partnership and one of five key energy efficiency accelerators of Sustainable Energy for All.

Lily Riahi, Sustainable Energy in Cities Advisor, UN Environment Programme