DPE calculations ‘ignore centuries of building practice’, says housing expert

France’s system of energy performance ratings (DPE) is meant to encourage greener homes – but critics say it is unfairly penalising some of the country’s oldest and most resilient buildings. 

Maisons Paysannes de France (MPF), an association founded in 1965 to preserve traditional rural houses, warns that the current system overlooks centuries of proven construction methods, and in doing so risks not only distorting the housing market but also damaging the very properties it seeks to improve.

“What is incredible is that the technocrats who designed the software used for the scheme totally ignored the centuries of house building which went on in France before 1948,” Gilles Alglave, its president, told The Connexion.

“These houses do not need added insulation on the walls or floors to stay cool in summer and warm in winter, mainly because they are built with natural stone, earth and wood. This means they have enough inertia built into them to remain comfortable all year.”

He added that when people try to insulate thick stone walls with modern materials, it can stop the walls from “breathing” – regulating their humidity through evaporation.

This can result in rising damp, hidden behind the insulation, which can cause serious structural problems.

“Unfortunately, in 15 years’ time some owners are likely to be left with no option but to demolish because of damp problems caused by insulation,” Mr Alglave said.

Similar problems are caused when wooden window frames are replaced with PVC equivalents.

“I can only conclude that things have reached this point because most of the technicians and politicians live in big city flats and have no experience of living in old homes.”

The current DPE system prohibits homeowners with the worst F and G ratings from renting out their properties. 

Those with properties rated E or lower must also provide an energy audit to potential buyers showing what work would be needed to boost its energy efficiency.

'Tinkering of DPE has to stop'

In July, the system for calculating DPE ratings was tweaked to allow homes using electric heaters to potentially climb out of the rental ban zone (see left), but Mr Alglave insists such “tinkering” has to stop.

“I have heard of people who had efficient gas heating, which gave them a poor DPE rating, going down to the DIY shop and buying four €300 electric radiators to suddenly get a better rating.

“However, the tenants will be paying far more and consuming far more energy with the little electric heaters than if the efficient gas system had stayed in place.

“In another case someone who inherited an old, comfortable house got a G rating when he was thinking of selling it. An energy audit detailed all that had to be done to raise the rating, and it came to three times the property’s value!”

The MPF has worked with various government agencies to provide data to back up its claims that the system unfairly penalises old homes.

Mr Alglave said it was important that politicians “stopped being destructive in parliament and became constructive instead.”

He added: “All parties say there is a housing crisis, but at the same time they all just seem to accept the DPE as it is, which is taking increasingly large numbers of properties out of the rental market, unnecessarily.

“It is important that they unite over this issue.”

Mr Alglave grew up and worked in Paris, mainly living in flats, before moving with his family to a 15th-Century house in a small village, which he restored.

“It has given me a good grounding and a foot in both rural and urban worlds,” he said.

“I feel that most politicians only see the cities, and have very little contact with rural areas where most of the older houses, which make up a third of the nation’s housing stock, are situated.

“If they worked on this issue they would probably appreciate other rural issues more than they currently do as well.”

He said he is encouraged by the number of architects and builders who are coming to the association to learn more about old buildings after realising their basic training in the area was inadequate.

“That is why it is so important to have a scientific base for what we are saying about the thermal efficiency of old buildings. 

"It gives a greater chance that the absurdities of the present DPE system will stop.”