Housing stock has the dual specificity of being inflexible and extremely diversified. Making housing more energy efficient involves acting on new construction, by setting regulations and improving technologies, as well as on existing construction through renovation, which is a long and costly process.
In 2003, residential housing and commercial buildings accounted for around 30% of the world's energy consumption.
Although it is difficult to obtain hard figures for developing countries, it is generally considered that virtually all biomassIn the energy sector, biomass is defined as all organic matter of plant or animal origin... is burned in homes, particularly for cooking, heating and lighting.
In France, 58% of homes were built before 1975
In Europe, housing is the economic sector that consumes the most energy, ahead of transportation, accounting for 40% of the total. In France, despite energy efficiencyIn economic terms, energy efficiency refers to the efforts made to reduce the energy consumption of a system... policies implemented since the first oil crisis of 1973, the sector's consumption has increased by 20% in 30 years.1 This consumption directly impacts consumers' buying powerIn physics, power is the amount of energy supplied by a system per unit time. In simpler terms, power can be viewed as energy output..., particularly in a period of rising energy costs.
Renovating Housing Stock
The difficulty lies in the inflexibility of housing stock. The average life of a building is over 100 years. 58% of French housing units (nearly 20 million) were constructed before 1975 and consume two to three times more energy than recently constructed units.
The annual energy renovation rate for existing stock stands at around 1% in France, as in Germany, despite German leadership in this area. Even with the very proactive policies pursued by both countries, neither expects to do more than double their objective by 2020.2
Older buildings consume two to three times more energy than recent homes.
Moreover, most renovations only achieve modest energy savings of around 20% to 30%. In order to achieve the full economic and ecological potential, massive - and hence costly - renovations bringing energy savings of at least 60% will have to be promoted.3
In France, the Grenelle Environmental Summit set an objective of 400,000 renovations per year as from 2013. This objective has not been reached; the annual number of major renovations is estimated at between 100,000 and 200,000. Yet a new objective of 500,000 renovations by 2017 has been set in the Energy Transition Bill (see Close-up: France's Energy Transition Bill).
One driver for more rapid progress would be to assign a "green rating" to buildings based on energy performance (see Close-up: Energy Performance Certificates). This factor is gaining ever greater importance in real estate transactions, on a par with the property's surface area, location and amenities.
New Construction in France
New construction, on the other hand, provides hope for rapid progress thanks to new building technologies. The latest thermal regulations (RT2012), which apply to building permits filed as from January 2013, introduced an average ceiling of 50 kWh of primary energyAll energy sources that have not undergone any conversion process and remain in their natural state.. (pe)/(square meter per year), compared with the 2005 standard of 150 kWh(pe)/(square meter per year).4
This ceiling varies according to different factors, such as the region or the altitude and applies to five regulated uses: heating, cooling, ventilation, domestic hot water and lighting. It's worth noting that energy consumed for heating decreased by 10% between 1990 and 2011 thanks to the improved energy efficiency of buildings. But electrical consumption in the home increased by 80% during the same period due to the growing number of household appliances and IT devices.
The next set of French regulations being prepared for 2020 - the Responsible Building Regulations (RBR) - will focus on the concept of the positive energy building. Building permits filed after January 2021 will have to show that the building will consume less energy than it produces from renewable sources.