19/08/2008 4:21 pmBuildings account for 40 % of the energy consumed in Europe. But, according to the United Nations, by 2010, over a fifth of these buildings' energy consumption could be saved and 45 million tons of CO2 emissions could be avoided. This is why more ambitious norms for new and existing buildings and the development of new forms of construction such as the passive house need to be considered.
Energy consumption in buildings
Buildings (heating, air conditioning, hot water, lighting, etc.) account for 40 % of the energy consumed in Europe. In France, it is the economic sector which consumes the most energy (2/3 in the housing sector and 1/3 in the tertiary sector); this represents almost 1 ton of oil per person per year and is the source of at least 21 % of the nation's cO2 emissions.
This consumption is experiencing a sharp rise. In France, it has increased by 30 % over the last 30 years due to the increase in the number of houses, in average occupied surface, increased comfort and the more widespread use of electricity.
Energy efficiency targets
The building sector could save large amounts of energy. According to the United Nations Environment Program (UNEP), over a fifth of energy consumption and more than 45 million tons of CO2 could be avoided in Europe by 2010.
In the long term, it could make even more savings and play a large part in reducing greenhouse gas emissions. (France has pledged to emit 4 times less greenhouse gas by 2050 – this is the « factor four »).
La directive sur la performance énergétique des bâtiments
Le secteur du bâtiment est régi par un environnement réglementaire important. En Europe, une directive sur la performance énergétique des bâtiments fixe pour les Etats membres des exigences minimales en matière de performance énergétique pour les bâtiments neufs et existants.
Sa transposition par la France s’est traduite par une nouvelle réglementation thermique des bâtiments neufs (RT2005) avec comme objectif principal une amélioration de la performance énergétique des bâtiments neufs d'au moins 15% par rapport à la RT2000, ce qui correspond à une consommation de chauffage d’environ 85 kWh/m2/an. Cette réglementation impose une limite de consommation énergétique de référence à ne pas dépasser pour tous les projets de construction à compter du 1er septembre 2006.
Pour l’ancien, la rénovation bénéficie d'une réglementation thermique spécifique, applicable aux bâtiments de plus de 1.000 m2 de surface et faisant l'objet de travaux de réhabilitation importants.
Indeed, buildings' energy performances can already be considerably improved and the energy they use can be produced by renewable sources. The installation of insulating windows saves 7 % heat energy, an efficient boiler saves 15 %, insulating the walls saves between 10 and 15 %, insulating the roof between 10 and 20 % and the installation of an individual solar water-heater or a heat pump can save up to 70 % of energy consumed to produce hot water. Efficient household appliances (class A or B washing machines or refrigerators) might consume almost half the energy of non-efficient ones.
Town-planning choices also have an important effect on energy consumption (transport layout, access to renewable sources of energy, eco-conception, ...)
Very eco-friendly buildings
There are many techniques and methods for reducing a building's energy consumption; this is why there are a lot of labels. The High Quality Environmental standard for « high eco-friendly quality » in France, aims to set out a coherent and global outline which applies the principles of sustainable development. It takes the building’s conception, construction, functioning and deconstruction into account.
Passive houses and positive houses
A well-adapted conception, with materials, insulation and optimised ventilation makes very low energy consumption possible. This is a passive house, from the German « Passivhaus ». Switzerland has created an equivalent label: « Minergie ». This norm means the house needs less than 15 kWh/m2/year for heating and consumes a maximum of 42 kWh/m2/year (heating, hot water, electricity) in energy. In comparison, buildings consume close to 400 kWh/m2/year on average.
Certain constructions can even produce more energy than they consume: they are called « positive houses ». They need to have photovoltaic panels installed on the roof, lighting which encourages natural light, manage rain water…
A slow evolution
In Europe, just over 5000 passive houses have been built. Different pilot projects exist here and there but they are not large-scale. For example, the European Program, CEPHEUS (Cost efficient passive houses as European standards) managed to build 250 buildings in five European countries, including France, through the Salvatierra residence in Rennes where 43 houses were built in 2002. In comparison, about 350 000 houses are built a year in France.
It is not just a question of price, as, in Germany, a passive house costs the same price as a standard house. In France, it is only 5 to 10 % more expensive than a classic house and this additional cost is rapidly earned back. There is also a lot of financial help available. In France, the Agence nationale pour l’habitat (the National Habitat Agency) offers allowances, the government offers tax rebates and the Caisse d’Allocations Familiales (Family Allocations Office) offers loans.
It seems that a lack of information on the financial incentives and how to save as well as the construction sector's rigidity are preventing things from evolving faster.
(2) ADEME, Bâtiments http://www2.ademe.fr/servlet/KBaseShow?sort=-1&cid=96&m=3&catid=12846
(3) Programme des Nations unies pour l’environnement, rapport « Bâtiments et Changement Climatique : Etat des lieux, Enjeux et Opportunités »
(6) Association HQE (marque déposée), http://www.assohqe.org/
(11) Chiffres clé du Bâtiment, Ademe.
(12) La Maison pasive