What water do I heat myself with?

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What water do I heat myself with?

Team Laurence's new offices in Sainte-Adèle.

It's a postcard setting: amidst the colors of autumn, the new head office of the firm Équipe Laurence sits proudly on top of a hill in the Laurentians.

But one detail is wrong… Right next to it is a purification basin for Sainte-Adèle's wastewater!

In fact, it is an ideal neighbor, because it provides all the energy needed to heat and cool the building.

“It's a bit of a trial run in our project. That has never really been done, as far as we know, in Quebec. »

— Alexandre Latour, President of Team Laurence

Alexandre Latour, president of the firm Équipe Laurence.

< p class="e-p">The idea was born in the mind of Alexandre Latour, who chairs a firm specializing in civil engineering. Sewer pipes and purification basins are his domain. The heating of buildings and energy efficiency is that of his brother Dominic Latour, who also heads an engineering firm.

“He's the one who took us out of our comfort zone a bit, who said to us: ''Why don't we do that?''”

— Dominic Latour, President and CEO of Bouthillette Parizeau

Together, they designed a system that allows heat to be transferred between the building and the purification basin. Both are connected by pipes, in which circulates an antifreeze liquid, glycol. Arriving in the basin, the glycol is distributed in a dozen pipe coils, which are submerged in the wastewater.

The installation of one of the coils that serve as a heat exchanger.

The glycol circulates in these various pipes before returning to the building. The waste water remains in the basin. Everything therefore forms a closed loop, which can be used both for heating and air conditioning.

A closed loop connects the building and the wastewater basin.

In summer, the heat from the building is transferred to the glycol, which is routed to the pool. By winding through the pipes, the heat is dissipated and the glycol rises cooler, which allows the building to be air-conditioned.

Heating mode is less intuitive. In winter, the temperature of the wastewater in the basin, like that of the glycol that goes back to the building, will be barely 5 degrees Celsius. The principle is to extract some energy from the glycol, the equivalent of a few degrees, and return it to the pool, where it will “heat up” to 5 degrees Celsius.

At each cycle, the system therefore recovers a little energy and accumulates it. It is this energy that is used by the building's heating system.

Alexandre Latour's project is based on an already known principle, that of hydrothermal energy, i.e. the extraction of heat from the water of a lake or a river. But it is a little used principle, in particular because it modifies the temperature of the water, which can harm aquatic animals and plants.

A pool of sewage obviously does not have this problem. And as a bonus, the water that ends up there is constantly renewed by the arrival of waste water from the toilets, but also from the showers, dishwashers and others. In short, it is warmer than that of a lake and therefore contains more available energy.

After a few months of running in air conditioning mode, the system is ready to face its first winter. And according to the first results, the heat exchange with the wastewater basin is so efficient that we could heat a second building, almost as big.

Alexandre Latour does not regret having invested money in it, but above all, countless hours to make sure everything works.

“When you're the first to do something [you ask yourself], 'Why hasn't anyone done it? Of course there is a reason!'' […] It was a risk that was very stressful for several months or even a year, but we are happy with the result. »

— Alexandre Latour, president of Équipe Laurence

And we now have all the data to make optimized systems. And it's sure to be repeated elsewhere in Quebec and Canada, adds Dominic Latour, President and CEO of Bouthillette Parizeau.

The presence of heat exchangers in the basin does not seem to affect the purification basin, which could convince other municipalities to take an interest in this brown gold. Moreover, in Sherbrooke and the Laurentians, other projects are already on the drawing board.

The report by Tobie Lebel and Jean-François Michaud is broadcast on the x27; Discovery show on Sundays at 6:30 p.m. on ICI Radio-Canada Télé.

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