Meeting the 1.5 degrees C (2.7 degrees F) temperature limit means that all of the global building stock will need to be net-zero carbon in operation by 2050 at the latest. In order to reduce existing buildings’ energy and emissions intensity, all existing buildings that are not net-zero and are eligible for retrofits need to undergo a deep retrofit to that standard.
Retrofitting includes energy efficiency improvements, such as the installation of double-glazed windows to improve heat retention or upgrading installation, and decarbonization measures, such as replacing fossil fuel-based heating systems with electric systems. It also means upgrading energy-consuming devices and appliances to more efficient versions. Supporting access to resources necessary to undertake these retrofits — including materials, skills and financing — will be vital to ensuring accessibility and implementation.
Doing so requires a retrofitting rate of 2.5%–3.5% of existing buildings each year by 2030, with higher rates required and reached, in developed countries with substantial existing stock. According to the IEA, less than 1% of buildings are retrofitted every year, which is well below what is required to meet the targets for deep retrofitting.
Data on deep retrofitting rates does not exist for many countries, and where data is available, the information is usually for single years (see, for example, the EU Building Stock Observatory). Due to insufficient data, it is not possible to give a quantitative estimate of how much deep retrofitting needs to accelerate to meet the 2030 target, but it is clear that the pace needs to increase dramatically in the coming decade.