The underground temperature is steadier than surface air, and guiding air through the earth into a home can boost cooling in summer and warming in winter. Depending on the setting, this approach can dramatically cut energy use or even eliminate it for temperature control. Geothermal air conditioning stands as a practical solution to energy shortages anticipated this winter and remains an economical, eco-friendly option.
Canadian wells, sometimes called Provence in older terminology, represent a form of geothermal air conditioning chosen for its straightforward setup and reliable performance. In this system, pipes are laid beneath the structure and connected to the home to regulate indoor temperature. Because it relies on natural heat exchange rather than drawing power from the grid, there is only a one-time installation cost. Once in place, operating costs drop because climate control relies on ambient underground temperatures rather than expensive electric heating or cooling.
Typical temperature differences in a Canadian well occur between winter and summer. In winter, the underground air tends to be warmer than outside air, and in summer the reverse happens, with underground air cooler than the air inside the home. This natural temperature buffering provides a passive source of heating and cooling, reducing or even eliminating electricity use for conditioning the interior environment.
The principle behind Canadian wells is straightforward: air stored in underground ducts is cooler than indoor air during the hot months and warmer during the cold months. This natural temperature exchange can warm the home in winter and cool it in summer without electricity for the fans or compressors often required by conventional systems.
Adopting this bioclimatic strategy can markedly improve a building’s energy efficiency. If installation occurs during construction, costs are typically lower than retrofits, though the benefits remain evident in either case. The surface temperature remains aligned with the surrounding environment, while at depths of two to three meters the underground temperature tends to stay constant around 18ºC–24ºC, a range conducive to comfortable indoor climate control.
The concept relies on channels laid two to four meters deep and about 35 meters long, through which air is circulated. When the air passes through these ducts, it gains or loses heat from the surrounding soil, thus delivering warmed or cooled air to the living spaces, with optional additional warmth if desired.
It is often noted that at around 15–20 meters there can be a year-round constant temperature, while at shallower depths around three meters the ambient climate already approaches comfortable home temperatures between 18ºC and 24ºC.
Soil assessment matters
Before installing a Canadian well, the soil is examined to understand its thermal conductivity and other properties that affect performance. This evaluation helps determine the system’s full potential and any drawbacks. Soil conductivity varies with porosity and saturation. For example, granular soils with clay or silt generally conduct heat more effectively than sandy soils. Conversely, clean sandy soils exhibit low conductivity when dry but improve markedly when saturated. Water presence strongly influences soil thermal properties, including conductivity and heat capacity.
Winter performance
During winter, the outside air is chilly, but two to three meters below the surface the temperature is higher. As outside air moves through underground ducts, it warms and improves indoor climatic conditions when it reaches the living spaces. In many cases electric heating can be reduced significantly or avoided altogether, depending on the site and design.
Summer performance
In summer, surface temperatures rise while underground temperatures stay cooler. Air traveling through the underground network cools before entering the home, delivering a few degrees of cooling and reducing or even preventing the need for air conditioning or extensive ventilation.
Citation: About Haus portal describes how to construct a canadiense well and explains the temperature dynamics and system design. (citation: About Haus)