Combining the projections on population development, GDP growth and energy intensity results in future development pathways for the world’s energy demand. These are shown in Figure 17 for both the Reference and the energy [r]evolution scenarios. Under the reference scenario, total energy demand will more than double from the current 19,000 PJ/a to 47,000 PJ/a in 2050. Under the energy [r]evolution scenario, a much smaller 50% increase on current consumption is expected by 2050, reaching 29,000 PJ/a. This is 40% less than projected in the reference scenario.

An accelerated increase in energy efficiency, which is a crucial prerequisite for achieving a sufficiently large share of renewable sources in energy supply, will be beneficial not only for the environment but from an economic point of view.Taking into account the full life cycle, in most cases the implementation of energy efficiency measures saves money compared to increasing energy supply. dedicated energy efficiency strategy therefore helps to compensate in part for the additional costs required during the market introduction phase of renewable energy sources.

Under the energy [r]evolution scenario, electricity demand is expected to increase disproportionately, with households and services the main source of growing consumption (see Figure 18). With the exploitationof efficiency measures, however,an even higher increase can be avoided, leading to electricity demand of around 2,400TWh/a in the year 2050. Compared to the reference scenario, efficiency measures avoid the generation of about 1,000TWh/a.This reduction in energy demand can be achieved in particular by introducing highly efficient electronic devices using the best available technology in all demand sectors. Introduction of solar architecture in both residential and commercial buildings will help to curb the growing demand for active air conditioning.