Tackling rising emissions in Grenoble’s walls

15 December 2020

After a series of years wracked by extreme temperatures, wildfires, floods and drought, France is already becoming acquainted to the effects of climate change. Nestled high in the Alps, Grenoble has been a witness to this change more than other cities.

But the Grenoble-Alpes Metropole, a member of the Covenant of Mayors for Climate & Energy, has high ambitions to tackle climate change. Just one area of their wide-reaching strategy is to reduce energy consumption in private homes by retrofitting buildings constructed in the post-war years.


The project, Mur|Mur, plays on the French words for ‘wall’ and ‘whisper’, and aims to target the areas that hold the largest percentage of energy consumption: industry and housing, carrying 40% and 24% respectively in France. Mur|Mur focuses on improving thermal insulation in condominiums built in the sixties and seventies to reduce CO₂ emissions and make the buildings more energy efficient.

What’s more, in a country where poverty and precarity remain important social issues and fuel prices remain some of the highest in Europe, the scheme should help reduce tenants’ heating and hot water bills.

“We opted for the insulation of the attic, the installation of a controlled mechanical ventilation, as well as the installation of a stove with granulated wood,” says Bertrand, a resident from the village of St-Paul-de-Varces, south of Grenoble. “By doing so, we have reduced our heating bill by half and increased our comfort with a final total cost way lower than we initially expected.”

A tower block undergoing renovation in Grenoble.
A tower block undergoing renovation in Grenoble.


Mur|Mur has resulted in the retrofitting of 4,467 buildings, leading to more than 5,200 tonnes of saved CO₂ emissions. The project has also succeeded in creating local jobs in the construction sector due to the work required. Now, Mur|Mur will be extended under the name Mur|Mur 2 to allow the retrofitting of other types of homes in the 49 communes of the Grenoble-Alpes Metropole: single-family dwellings and private co-owned multi-occupancy buildings.

The project helped residents pay for the retrofitting, a key point of success, according to David-Albert Billiote, Mur|Mur Project Manager.

“The financial support is one of the keys to the success of Mur|Mur 2 – it covers up to 75% of the cost of the works for very modest households,” he said.

And the project won praise from residents when it came to the help that was provided for the renovations. “It allowed us to benefit from the unbiased advice from an expert guiding us through the work,” says Jennifer from Saint-Egrève. “For instance, I received advice on the choice of the insulating material and the boiler.”

Valuable lessons

But the project wasn’t without challenges. Targeting mainly co-owned housing, Mur|Mur had to convince a majority of co-owners to vote for the retrofitting. In addition, many families in the targeted buildings lived under considerable financial strain, meaning that paying for the renovations was difficult. Subsidies from the metropolitan authority and its partners were paid retroactively, leaving many households in the lurch.

Grenoble did learn valuable lessons from the project. It was clear that the red tape linked to the retrofitting needs to be simplified and homeowners must receive dedicated and effective support. Following the project, a one-stop shop was set up to receive feedback from co-owners and building managers and to guide residents through the administrative jungle.

“What I really enjoyed was the selfless and personalised advice from experts which served as the basis for the preparation of my invoices,” said Oliver from the suburb of Seyssinet-Pariset. “There’s a lot of information on the internet, it’s not easy to sort it all out. Mur|Mur gave me a global and neutral perspective so that my project was as coherent as possible.”

The city sees the policy as a success – so much so that they plan to make insulation retrofitting of older buildings a permanent public policy. And in October, the Metropolitan Council voted for a new Mur|Mur for SMEs and very small enterprises with the goal of renovating 25 businesses in 2021 and up to 200 by the end of its new political mandate in 2026.

The full results of the Mur|Mur project can be downloaded here.