Buildings energy conservation and efficiency

If we turn lights off in our homes when we do not need them, if we turn down the thermostat by a degree or two so that we are less warm or less cool or if we add more insulation to our home, we are conserving or indeed saving energy.

Figure 11.6 Where are we heading? - the need for an energy strategy. The boat flies national and UN flags to illustrate the need for national and international strategies.

But are such actions significant in overall energy terms? Is it realistic to plan for really worthwhile savings in our use of energy?

To illustrate what might be possible, let us consider the efficiency with which energy is currently used. The energy available in the coal, oil, gas, uranium, hydraulic or wind power is primary energy. It is either used directly, for instance as heat, or it is transformed into motor power or electricity that in turn provides for many uses. The process of energy conversion, transmission and transformation into its final useful form involves a proportion of the primary energy being wasted. For example, to provide one unit of electrical power at the point of use typically requires about three units of primary energy. An incandescent light bulb is about 3% efficient in converting primary energy into light energy; unnecessary use of lighting reduces the overall efficiency to perhaps no more than 1%.12 Assessments have been carried out across all energy uses comparing actual energy use with that which would be consumed by ideal devices providing the same services. Although it is not easy to define precisely the performance of such 'ideal' devices (see box below for a discussion of thermodynamic efficiencies), assessments of this kind conclude that there are large opportunities for improvement in average energy efficiency, perhaps by a factor of 3 or more.13 In this section we look at possibilities for energy saving in buildings; in later sections we consider possible savings in transport and in industry.14

To be comfortable in buildings we heat them in winter and cool them in summer. In the United States, for instance, about 36% of the total use of energy is in buildings (about two-thirds of this in electricity), including about 20% for their heating (including water heating) and about 3% for cooling.16 Energy demand

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