Mitigating CO2 emissions from energy use in the world's buildings.

An overview of climate change mitigation opportunities in the world's buildings is presented, based on the key building-specific findings of the Fourth Assessment Report from the Intergovernmental Panel of Climate Change. Buildings and the building stock can play a major role in mitigating climate change in the short- to medium-term, since substantial reductions in CO2 emissions from their energy use can be achieved over the coming years. A significant portion of these savings can be achieved in ways that reduce life cycle costs, thus providing reductions in CO2 emissions that have a net negative cost. There are indications that the building stock has the highest share of negative- and low-cost greenhouse gas reduction potential among all sectors. Based on 80 collected national or regional studies estimating CO2 mitigation potential in five continents, the global potential for CO2 reductions through buildings is analysed and estimated. The co-benefits associated with the implementation of these measures are also substantial, helping policy-makers justify actions even in the absence of a strong climate commitment. Since the barriers to unlocking the high potentials in the residential and commercial sectors are especially strong, no single instrument can make a large impact. Instead, portfolios of targeted policies tailored to local conditions, combined with strong compliance and enforcement regimes, are needed.