Energy Transferred by Working
Energy and Thermal Physics

Living comfortably

Physics Narrative for 11-14 Supporting Physics Teaching

Energy for the home

Another everyday concern is the energy balance in our homes. In Northern Europe, mostly keeping the house warm enough in winter, but sometimes also keeping it cool in summer. Again, energy provides a fundamental limiting factor. If we do not have access to sufficient energy we cannot stay warm enough (or cool enough).

The quantities required are even larger, so now we measure the energy in millions of joules, or megajoules (MJ). The following UK figures for average energy consumption per household by final use in megajoules show some interesting changes in domestic energy usage over a time period of 30 years.

yearwarming homeswarming watercookinglighting and appliancestotal
197157 55227 4565808792098 736
198160 72025 344475211 088101 376
199162 83224 288369612 672102 960
200163 88823 760264013 200103 488

Comparisons across time

The general pattern is that increases due to increasing number of houses are being partially offset by more efficient use of resources, but there is also increased demand caused by changing lifestyles (about 5 % increase per household over the period shown). These patterns are broadly similar to other Northern European countries. Canada and the USA use considerably more resources.

Regional energy statistics for the whole of the UK are not currently available, although a number of regions are concerned to collect this data, to ensure enough energy is made available over the course of a year. One big advantage of having the common energy currency is that gas and electricity can be compared directly in terms of what you can do with each.

For example, the total annual demand for energy in South-East England is about 32,400 megajoule for each person, with approximately 75 % of this being met by gas. This preference for gas may be due in part to price. In 2000, in the South East, electricity cost the consumer 7.4 p for 3.6 megajoule, while the same quantity of energy delivered by gas cost only 1.6 p. Since energy is supplied in an open market, it is no surprise that there is a whole range of calculators on the Internet to help you estimate your energy needs and to work out how to best provide this energy. The lowest financial cost solution is often to use a mixture of gas and electricity. The common currency of energy allows such calculations to be made, comparing energy costs for equal periods of time.

Energy Transferred by Working
appears in the relation dU=dQ+dW
is used in analyses relating to Working Engines Thermionic Emission
is a special case of Work
has the special case Potential Energy Kinetic Energy
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