Created in 1952, ‘La Cigale’ is a housing cooperative comprising 273 apartments in two buildings located in Geneva, on the corner of the Rue de Vermont and the Rue du Vidollet.

57 years after their construction, a full renovation of both cooperative buildings’ façades and a new heating system was undertaken.

In this context, Brolliet, which has been responsible for managing the Cooperative since its creation in 1952, and its partners, submitted a sustainable renovation proposal to the ‘La Cigale’ buildings’ members. The objective was both clear and ambitious: to achieve close to a 70% reduction in the buildings’ heating requirements thanks to improved energy performance and less dependency on fossil fuels, with the aim, therefore, of obtaining Minergie-P® certification.

Unanimously accepted by the cooperative’s members, Brolliet took on the role of pilot and leading consultant for this operation and set up a group of experts including architects François Baud and Thomas Früh, BG Ingénieurs Conseils SA, Signa-Terre SA, Geneva Industrial Services (SIG) and UBS to manage investment and fundraising.


La Cigale before renovation

La Cigale after renovation


Every possible measure was taken so that the major renovation operation would create the least possible impact on the quality of life of ‘La Cigale’ members. In this context, work lasted only one year, from 2013 to 2014, and mobile scaffolding was put up and relocated as the prefabricated elements and loggias went up. This innovative solution enabled all renovation work to be implemented from outside the buildings, allowing all residents to remain in their apartments throughout the duration of the work.

In order to meet the set energy objectives, the cooperative selected a highly innovative heating concept designed by Energie Solaire SA comprising a hot water and heating generation system combining a heat pump, ice accumulator and solar thermal roofing covering 1700 m². It utilises low-temperature solar contributions and is therefore able to cover over 80% of the renovated buildings’ heating requirements using solar energy. The heat pumps use ‘Vitale Vert’ energy from SIG, enabling the ‘La Cigale’ buildings to be supplied with 97% renewable energy. Finally, a small natural gas source is conserved to provide backup heating in exceptional weather conditions, thereby guaranteeing tenant quality of life.

Rent levels, which were also taken into account, were a key element in the conception of this project in order to respect the cooperative’s operating philosophy. This involved a financial plan implemented by Brolliet in order to restrict, as far as possible, the repercussions of the work on members and keep rent levels below market average, i.e. approximately -50%.

By virtue of its size, the Minergie-P® ‘La Cigale’ renovation project is unique in Switzerland. And the work carried out had a considerable impact, representing 98% of the Minergie-P® surface area of transformations in the Canton of Geneva!

Despite the cost of such a renovation, estimated at CHF 18.5 m, obtaining Minergie-P® certification on such high volumes makes this project the first of its kind in Switzerland. In addition, the active partnership between the different stakeholders and members of ‘La Cigale’, all the social, ecological and financial solutions implemented make the renovation of ‘La Cigale’ a pilot experience, fully reproducible in Switzerland.