The heat of the earth, which varies little unlike air, can be used to heat or cool a building. This is called a Canadian well.
What is the principle of the Canadian well?
The Canadian well, also known as the Provençal well, is a so-called surface geothermal system, which consists in using the thermal inertia of the ground to preheat the fresh air for building renewal. In France, the outside air temperature can range from - 20 ° to + 35 °, while the ground temperature a few meters deep remains relatively stable, with just a few variations depending on the season.
How does the Canadian well work?
The outside fresh air circulates in buried pipes thanks to a ventilator, before being blown into the building. In winter, the air warms up on contact with the ground to reach a frost-free temperature. The heating needs linked to air renewal are then limited and the building can be kept frost-free, which is practical for a house which is not occupied all year round. In summer, the outside air takes advantage of the coolness of the soil to cool and arrive in the house at a temperature between 15 and 22 °. In the off-season, a bypass short-circuits the well when the comfort temperatures (18 ° to 24 °) are reached.
What is a Canadian well made of?
The Canadian well consists of: - An air intake mouth with a grid and a filter (against rodents and insects). - One or more pipes for the passage of air with a slope greater than 2% to allow the evacuation of the condensation and avoid the risks of mold and residual humidity. However, they should be cleaned with plenty of water regularly. - A manhole to inspect the installation and place a pump there to drain the cleaning water. - A by-pass to short-circuit the Canadian well in the off-season, when the temperature is between 18 and 24 °. - A fan to force and regulate the air flow to distribute in the house. - A single-flow or double-flow ventilation system depending on the quality of the home's energy needs.
Why a Canadian well?
Because the Canadian well is part of a bioclimatic approach. It achieves a range of comfort combining temperature, humidity and air speed by using energy-consuming techniques such as heating and air conditioning as little as possible. Attention: In parallel, it is imperative to respect two basic principles: - Limit losses (good choice of partitions and glazing, building materials with high inertia, efficient insulation) - Optimizing energy inputs (good orientation of glazing, roof overhangs, solar shading, judicious planting). To know more : "The Canadian Well", Bruno Herzog, Eyrolles editions.