The buildings sector model is modelled using a global simulation stock accounting model, split into residential and services sub-sectors and applied across 31 countries or regions (Figure A.6). The residential sub-sector includes those activities related to individual dwellings. It covers all energy-using activities in apartments and houses, including space and water heating, cooling, lighting, and the use of appliances and electronics. The services sub-sector includes activities related to trade, finance, real estate, public administration, health, food and lodging, education, and commercial services. This is also referred to as the commercial and public service sector. It covers energy used for space heating, cooling and ventilation, water heating, lighting, and a number of other miscellaneous energy-using equipment, such as commercial appliances and cooking devices or office equipment.
For both sub-sectors, the model uses socio-economic drivers, such as income and population, to project floor space per capita and appliance ownership. As far as possible country statistics are used for floor area and appliance ownership rates in the base year. But especially for non-member countries of the Organisation for Economic Co-operation and Development (OECD), these data are more difficult to obtain, so in several cases these parameters have been estimated for the base year. The buildings floor area is differentiated by vintage, approximations based on other indicators (e.g. historical population) are used to estimate the vintage distributions if no statistical data are available for a country or region.
Based on the projections for floor area and appliance ownership, the model determines the useful energy demands, such as space or water heating, applying useful energy intensities, which take into account the vintage of the buildings as well as the ageing or refurbishment of the buildings through corresponding degradation and improvement rates for the useful energy intensities.
For each of these derived useful energy demands (e.g. space heating), a suite of different technology and fuel options are represented in the model, reflecting their current techno-economic characteristics (e.g. efficiencies) as well as their future improvement potential. Depending on the current technology stock as well as assumptions on the penetration and market shares of new technologies, the buildings sector model allows exploration of strategies for different useful energy demands and the quantification of the resulting developments for final energy consumption and related CO2 emissions.
Figure A.6 Structure of the buildings model