The introduction of new energy efficiency standards will increase the cost of house construction by up to 20% say experts.

The Réglementation Thermique 2012 (RT 2012) sets the new minimum standard of thermal insulation of dwellings and other types of construction in France.

It will be applicable to all new planning applications submitted for non-residential buildings from Oct 2011 and for all new residential properties from January 2013.

Although a complex set of standards, broadly speaking, the regulations require that all new dwellings must have an energy consummation level less than 50 kWh/m2 per year, although varied by locality and altitude within the range 40kWh/m2 to 65kWh/m2.

Source: Le Grenelle Environnement

The building standard RT2005 currently in operation sets a maximum level of energy consumption of 150 kWh/m2.

In a review of the challenges of the environmental challenges facing builders over the next few years, economic consultants Xerfi consider that these new standards will mean an increase in the build cost of new homes of between 15% to 20%.

This figure is far higher than the estimate of 7% to 8% given by the government when the new regulations were passed last year.

Xerfi consider that although the techniques for building eco-friendly homes exists, the cost of materials is often far higher, the regulations will require more preliminary studies to be undertaken, and the shortage of skilled labour will all push up the cost of housebuilding.

The authors consider that, in order for the new market for these homes to be successful, the energy savings promised by them will need to become a reality, house builders will need to sacrifice some of their profit margin, and the government will need to continue to provide fiscal support for house purchase and home energy conservation. ''La réussite dans la construction durable n'est pas gagnée d'avance'', say Xerfi.

The government estimates that there will be an average saving over 20 years of around €15,000 in the cost of energy consumption in homes built to RT2012 standards.

In terms of environmental benefits they estimate that it will save around 150 billion kilowatt-hours (KWh) of energy, and 13 to 35 million tonnes of CO2 over the period 2013-2020.