Buildings sector model
The buildings sector 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 all energy-using activities in apartments and houses, including space and water heating, cooling, lighting, and the use of appliances and other electronic plug-loads. The services sub-sector includes activities related to trade, finance, property, public administration, health, food and lodging, education and other commercial services. This sub-sector is also commonly referred to as the commercial and public service sector. It covers energy used for space and water heating, cooling and ventilation, lighting and other miscellaneous energy-consuming equipment such as commercial appliances, office equipment, cooking devices and medical equipment.
For both sub-sectors, the model uses socio-economic drivers, such as income (approximated by GDP) and population, to project the major building energy demand drivers, including residential and service floor space, number of households and residential appliance ownership. As far as possible country statistics are used for historical floor area and appliance ownership rates. These data can be difficult to obtain across many developing countries, so in several cases the historical driver parameters for the buildings sector model have been estimated using a series of applied logistic functions relative to GDP per capita for the particular country or region. Building floor area is then differentiated by vintage, where 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.
Figure A.6 Structure of the buildings sector model
Key point Starting from socio-economic assumptions, the buildings sector model determines demand drivers and the related useful energy demands, which are then applied across the building end uses and technology choices to calculate final energy consumption across the 33 model regions
Differentiated stock accounting is used to estimate historical useful energy intensity across the various building end uses with respect to assumed technology shares and efficiencies. Whenever possible, historical data on country/regional technology shares and efficiencies are applied. These useful energy intensities (e.g. demand for space heating per unit of floor area in terms of final delivered [i.e. useful] energy service) are then applied across the building end uses with the projections for floor area, households and appliance ownership. The model takes into account the vintage of the building stock 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 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 that cover the different useful energy demands and the quantification of the resulting developments for final energy consumption and related CO2 emissions.