2. Rational use of energy

The challenge of rational energy use is to keep building operating costs under control, despite a certain future increase in the price of the energy used, and to contribute to a reduction in pollutant emissions.

Moving backwards in time, the progression is striking, while maintaining the duality between technological evolution and economic or environmental constraints:

• Emergence of the science of Thermics between 1770 and 1830, due to the constraints of heating with increasing needs and decreasing availability of firewood;

• the emergence of new technical processes, such as hot water pipes in Great Britain, or new theoretical processes, such as Fourier's theoretical contributions in France;

• the transition from technology to science thanks to engineers...