Lyonnaise des Eaux-GDF SUEZ reuses the heat from wastewater to heat a public building – The city hall of Valenciennes

“Degrees blue” is a process developed by Lyonnaise des Eaux and installed by its subsidiary Eaux et Force in 2010 for the city of Valenciennes.

The principle of “Degrees blue” is to capture the heat from the effluents flowing into the sewers to heat buildings. This environmental and economical process promotes energy autonomy in communities through using an untapped a local resource. “Blue degrees” constitutes true green energy that meets the environmental challenges of tomorrow.

The technology used is relatively simple: an exchanger is placed at the bottom of the water piping. This heat exchanger is made of stainless steel plates that transfer the heat from waste water to the calorie carrier fluid inside it. This heat transfer fluid consisting of glycol recovers calories and directs them to the heat pump. It circulates in a closed loop inside the heat exchangers of the boiler room of the Town Hall building.

The heat pump then multiplies the calories taken and raises the temperature until it is sufficient to heat the building.