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 2014, residential and service-sector buildings accounted for 23% and 8% of final energy consumption respectively, worldwide. According to figures from the International Energy Agency (IEA)An independent, intergovernmental organization founded within the framework of the OECD..., the total is slightly higher than final energy use in industry (29%) and transportation (28%)1. However, evaluation is difficult in developing countries, where substantial amounts of biomassIn the energy sector, biomass is defined as all organic matter of plant or animal origin... are used in cooking and heating.
In France, 58% of homes were built before 1975.
In Europe, most energy (more than 38% in 2014) is used in buildings (24.8% residential and 13.3% service-sector), followed by transportation2. In France, residential and service-sector buildings together accounted for 42.6% of final energy consumption in 2015. After rising steadily during the 1990s (by 1.1% per year on average), consumption has shown little change since the early 2000s3.
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.
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.
France’s residential energy renovation plan (PREH), launched in 2013, set annual renovation objectives (to cover 380,000 privately-owned homes and 120,000 in the social housing sector by 2017).
One way to boost progress would be to assign buildings a “green rating”, based on energy performance (see Close-up: Energy Performance Certificates). This kind of rating is given increasing importance in real estate transactions, along with factors such as the property’s surface area, location and amenities.
New Construction in France
New buildings offer hope for rapid progress thanks to new construction technologies. The RT2012 thermal regulations applying to building permits filed from January 2013 introduced a ceiling of 50 kilowatt-hours of primary energyAll energy sources that have not undergone any conversion process and remain in their natural state.. on average per square meter per year, compared with 150 kilowatt-hours under the 2005 standard4.
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 efficiencyIn economic terms, energy efficiency refers to the efforts made to reduce the energy consumption of a system... 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.
Forthcoming French regulations, RT 2020, bring in the concept of positive-energy buildings (BEPOS). Building permits filed after January 2021 will have to show that the building will consume less energy than produced from renewable sources.
(1) IEA statistics