Energy management in buildings - Definitions. Usage. Consumption

Energy is a scarce, and therefore precious, resource. What's more, its consumption leads to discharges or emissions that are harmful to the environment, and its production mobilizes substantial financial resources that could be used for other purposes. Finally, the cost of energy, even at a level comparable to that prior to the 1974 oil crisis, weighs heavily on household and business budgets. For all these reasons, energy must be used rationally.

Energy resources can be broadly divided into two categories:

• those that are naturally renewable;

• those that are fossil, i.e. non-renewable on our human timescale.

On a national level, France is naturally poor in energy resources, and a large proportion of these must therefore be imported. The country's energy trade balance is by far its biggest deficit, resulting in a very large outflow of foreign currency. In 2000, France's energy bill (all sectors combined) amounted to 23.6 billion euros (155.2 GF), for an energy independence rate of 46.5%.

In particular, the housing and tertiary sectors, which account for energy expenditure in buildings, represent a significant proportion of this energy consumption (100.7 Mtoe in 2000), and this share is growing steadily. The proportion of imported energy (fuel oil and natural gas) remains considerable (62.5%), hence the importance of saving energy in this sector.

What's more, the international political context remains fragile: energy independence at a sufficiently high level is essential to ensure sustainable development, hence the importance of developing :

• domestic energy sources, preferably renewable ;

• the widest possible diversification of energy supply sources, leading to a choice of plants with the greatest possible versatility in terms of energy supply;

• controlling energy consumption to reduce users' vulnerability to crises and facilitate the use of renewable energies.

The following text defines the terms specific to the discipline before describing the services or uses rendered by energy in buildings. Micro- and macro-economic energy indicators complete this information to help situate the challenges of energy savings in the building sector.