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 6.4 for both the Reference and Energy [R]evolution Scenarios. Under the Reference Scenario, total primary energy demand almost doubles from 474,900 PJ/a in 2005 to 867,700 PJ/a in 2050. In the Energy [R]evolution Scenario, demand increases up to 2015 by 16% and decreases to close to today’s level of 480,860 PJ in 2050.

The accelerated increase in energy efficiency, which is a crucial prerequisite for achieving a sufficiently large share of renewable energy sources in our energy supply, is beneficial not only for the environment but also for economics. Taking into account the full service life, in most cases the implementation of energy efficiency measures saves costs compared to an additional energy supply. The mobilisation of cost-effective energy saving potential leads directly to a reduction in costs. A dedicated energy efficiency strategy thus also 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 6.5). With the exploitation of efficiency measures, however, an even higher increase can be avoided, leading to electricity demand of around 30,800 TWh/a in the year 2050. Compared to the Reference Scenario, efficiency measures avoid the generation of about 12,800 TWh/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. Employment of solar architecture in both residential and commercial buildings will help to curb the growing demand for active air-conditioning.

Efficiency gains in the heat supply sector are even larger. Under the Energy [R]evolution Scenario, final demand for heat supply can even be reduced (see Figure 6.6). Compared to the Reference Scenario, consumption equivalent to 46,000 PJ/a is avoided through efficiency gains by 2050. As a result of energy-related renovation of the existing stock of residential buildings, as well as the introduction of low energy standards and ‘passive houses’ for new buildings, enjoyment of the same comfort and energy services will be accompanied by a much lower future energy demand.

In the transport sector, it is assumed under the Energy [R]evolution Scenario that energy demand will increase by 12 % to around 94,000 PJ/a in 2015 and will fall slightly afterwards down to 83,300 PJ/a in 2050, saving 100,000 PJ compared to the Reference Scenario. This reduction can be achieved by the introduction of highly efficient vehicles, by shifting the transport of goods from road to rail and by changes in mobility-related behaviour patterns.