As part of the Agenda 2030 plan, the municipality of Bron in eastern France is pursuing an active approach to sustainable development. Since 1992 and the Agenda 21 plan, Bron has adapted its policy to reflect changes in the global context, setting up a dedicated committee and consulting local residents. To manage the energy performance of municipal buildings, Bron chose a service provider able to put forward a plan for maximum energy savings.

Renovating existing installations 

In line with the city's environmental plan, Idex set out a programme of works designed to deliver maximum energy savings. Our team has renovated 14 boiler plants in five years. The existing high-temperature gas boilers were replaced by condensing boilers. 

The energy efficiency of these boilers often exceeds 100% with the recovery of combustion gases, delivering energy savings of around 30%.

A highly efficient system, with lower emissions of CO² and other pollutants than conventional boilers.

In some buildings, including schools, the roof cavities were insulated to prevent heat losses in winter, and thermostatic valves installed. The total investment for the work budgeted with the municipality was amortised in under five  years, i.e. even before the end of the contract.

Managing energy use

For the past seven years, we have been managing 70 buildings for the municipality as part of an energy performance contract. When the contract was renewed after five years of operation, our operational technicians installed a building management system to oversee all the installations. All the buildings are connected to a single software programme, which monitors and adapts energy use in real time.


This system has reduced energy consumption by 10%. 

The buildings now also have controllers with optimisers. The control system maintains the required room temperature, taking account of natural heat gains.


This process gives priority to natural heat in order to reduce energy use.

70  buildings  

14 boiler plants renovated in five years

30% energy savings with the recovery of combustion gases from the boilers

10% reduction in energy consumption with the building management system