The underground temperature remains far more stable than surface air, so by channeling air into a home from below, cooling in summer and heating in winter can be improved. Depending on the site, energy use for heating and cooling can be substantially reduced or almost eliminated. Geothermal air conditioning serves as a viable response to winter energy shortages and is a clean, cost-effective option.
Canadian wells, sometimes called Provence wells, illustrate geothermal cooling and heating in action. They are gaining popularity due to their simplicity and low operational cost.
These systems involve pipes placed beneath a house and connected to interior spaces to regulate temperature. The setup does not require electricity for operation beyond the initial installation, so ongoing costs drop to a minimum. Once installed, home cooling and heating bills become noticeably cheaper as significant savings accumulate on every utility statement.
Typical temperature difference in a Canadian well in winter about home
summer operation about home
The basic idea behind Canadian wells is straightforward: the air stored in underground ducts tends to be cooler than indoor air in summer. In winter the situation reverses: underground air is warmer than indoor air. This natural heat exchange provides warmth in cold months and cooling during hot periods without extra electrical input.
This bioclimatic approach markedly improves a building’s energy efficiency. Installing during construction is cheaper, but the benefits remain clear whether done later or earlier.
Surface temperature tracks environmental conditions, but at depths of two or three meters the temperature stays fairly constant, usually within a comfort range of roughly 18ºC to 24ºC. This fact is noted by design guides.
The system lays channels at depths of 2 to 4 meters, extending roughly 35 meters, through which air circulates. The air contacts the ducts, adopts the floor temperature, and is then introduced into living spaces with optional heat input.
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It is estimated that a steady year-round temperature can be found around 15 to 20 meters underground. At shallower depths, around 3 meters, temperatures near optimum comfort levels (18º to 24º) become accessible for a home.
It is recommended to examine the soil beforehand.
Before installing a Canadian well, the soil is assessed for thermal conductivity and related properties to determine its full potential and any limitations.
Soil conductivity depends on porosity and saturation. For instance, granular soils with clay or silt transfer heat more readily than sandy soils.
Clean sandy soils conduct less heat when dry but more when saturated. Water presence strongly influences thermal properties, including conductivity and heat capacity.
In winter:
Outside air is cold, yet at two to three meters depth the underground temperature is warmer. When outside air travels through underground ducts, it heats up and improves indoor conditions, potentially reducing or eliminating electric heating, depending on the scenario.
In summer:
Outside air is hotter than the underground air. As it passes through the subterranean channels, it cools and reaches living spaces several degrees lower, boosting comfort and lowering or preventing air conditioning or ventilation needs.
Reference article: a practical guide on building a Canadian well
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