Buildings

The last report published by the Intergovernmental Panel on Climate Change (IPCC) confirmed that the average temperature of the Earth’s atmosphere would rise from 1.5 to 6°C by the end of the century. The actual increase will depend for the most part on the scope of the public policies implemented by the countries that consume the greatest amounts of energy and the dates upon which these policies are introduced.

Global warming has already caused disturbances to our climate, with extremely serious consequences to humankind, and the future looks even bleaker. To limit the effects and guarantee the sustainable development of society, it is agreed that world greenhouse gas emissions must be halved by 2050.

Bearing in mind that developing countries have very little room to manoeuvre (though their emissions are set to increase significantly), industrialized nations need to reduce their emissions by a factor of four or five within the next 50 years. France has already adopted this objective as part of its National Strategy for Sustainable Development, introduced in June 2003, and its Climate Plan, introduced in July 2004.

Meeting this objective translates into tolerable concentrations of greenhouse gases in our atmosphere, calculated at 450 parts per million (ppm), compared to today’s 380 ppm and some 280 ppm before the industrial age.

In the building industry, average annual energy consumption is currently close to 400 kWh of primary energy per heated sq.m. With a call to reduce CO2 emissions combined with the inevitable energy price increases caused by the gradual depletion of resources, the average primary energy consumption of operational buildings needs to be reduced to approximately 100 kWh per sq.m by 2050, including some 50 kWh/sq.m of primary energy for heating the premises and providing hot water.

In France, the building industry uses up 70 million tonnes of oil equivalent, making it the biggest consumer of energy across all sectors of the economy. In other words, this represents 43% of total energy consumption and 1.1 tonnes of oil equivalent consumed every year by every French citizen.

This energy consumption produces 120 million tonnes of CO2 emissions, representing 25% of France’s national emissions and 32.7 million tonnes of coal. This quantity is of the same magnitude as the amount of building-site and household waste generated annually, and is equivalent to one-half tonne of coal emitted into the atmosphere for every French citizen. All of these figures need to be reduced by 75% by 2050.

However, the annual volume of new construction (300,000 residences and 14 million sq.m of heated commercial buildings), the current stock of buildings (nearly 30 million residences and over 814 million sq.m of heated commercial buildings) and the extremely long life of such buildings are, in general, negative factors for rapid progress in the sector.
While the industry’s sluggish growth and inertia have long been considered handicaps compared to more dynamic sectors like industry and transport, the building sector is now considered in a much more favourable light.

The building sector is now set to play a significant part in tackling the troubling environmental challenges that we are now facing.

Just recently, it has come to light that this sector may be the only one capable of making significant enough progress to be able to meet our national commitments with regard to reducing greenhouse gases.

The paths of development in the building industry can be much more easily identified now than in previous years thanks to greater understanding in various areas :

• Buildings can use several energy sources, including renewable sources, which can also be combined. A building is not limited to one single energy source throughout its lifetime.
• Improvements to the energy performance of buildings can be scheduled over several years. Each new development increases the value of the property.
• A building’s occupants have relatively constant user habits over time. Their needs usually alter over long periods with no drastic changes, and can easily be anticipated.