From energy-saving refrigerators, low-consumption automobiles, and intelligent building management systems to resource-saving production processes in industry, energy efficiency is a versatile topic that is - and will remain - of great importance in all areas of our everyday lives. Solar technologies are characterized as either passive or active depending on the way they capture, convert and distribute sunlight and enable solar energy to be harnessed at different levels around the world, mostly depending on the distance from the equator.

51 Plug-in hybrids also have increased battery capacity, which makes it possible to drive for limited distances without burning any gasoline; in this case, energy efficiency program evaluation is dictated by whatever process (such as coal-burning, hydroelectric, or renewable source) created the power.

In essence, the UK energy market will either see the energy price cap temporarily suspended so that energy suppliers can recover, which would mean that consumers end up paying the cost, or the energy price cap remains in place and energy suppliers that cannot survive the competition go bust.

Similarly, investing in energy efficiency is almost always cheaper and cleaner for utilities than new generation resources—or even the fuel costs of existing generation—but such investments lead to reduced earnings potential under the traditional utility business model.