Cities are home to more than half of the world’s population. They consume more than two thirds of global energy and produce about 70% of greenhouse gas emissions. Cities are also drivers of economic growth. By becoming more energy efficient they can help mitigate the effects of climate change and contribute to the achievement of the Sustainable Development Goals – especially SDG7, which aims to ensure access to affordable, reliable, sustainable and modern energy for all. However, key institutional and financial challenges remain to mobilize investments, strengthen polices, and help cities plan ahead to avoid a lock-in of inefficient infrastructure.