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Natural Building Technology: Learn how natural air conditioning can efficiently, sustainably and economically cool your home, providing thermal comfort
Canadian wells, also known as Provençal wells (due to their use in the French region of Provence), are simple geothermal air conditioning systems. They consist of a network of pipes located underground outside homes, connected to them and which operate on the principle of thermal inertia to adjust the temperature of the air used in the home.
This construction system does not consume electrical energy, so after its installation, the air conditioning of our home will be more economical. Natural technology low cost, ecological, efficient and sustainable.
Installation of a Canadian Well Construction System
There are places where they are more effective in winter and others where they are more effective in summer. Now you will discover the difference.
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Its operating principle is simple: the air that accumulates in buried pipes is colder than the air in the house in summer, but warmer in winter. We have, without any electrical consumption, a heat exchange that we will use to heat in the winter and cool down in the summer.
The most effective and economical option is to install the Canadian well during the construction of the house, as installation later can be expensive.
This system significantly reduces energy demand. It is a very effective bioclimatic strategy for improving the energy efficiency of a building.
Thermal inertia
This property indicates the amount of heat that a body can conserve and how quickly it gives up or absorbs it. It is a property used in construction to maintain the temperature inside environments throughout the day. During the day, the walls heat up and at night they give off heat to the area; in summer, they absorb heat from the environment through a ventilation system and at night they cool themselves with a similar system.
In the case of Canadian wells, their operating principle is simple. The surface temperature presents a difference with that of the environment, this difference is accentuated and remains stable at approximately two meters depth, where the temperature generally remains between 18ºC and 24ºC. This is accentuated depending on the geographic location and climatic conditions. This temperature is known as the average temperature and if it is pleasant, it will be suitable for connecting the building to the earth. At 15 meters deep, the temperature is constant throughout the year.
A Canadian well is made up of a series of tubes placed at a specific depth – heat exchangers, which run a certain number of meters underground. In these pipes, air circulates, causing an exchange of heat between the air that circulates and the earth that surrounds it.
Hours
Winter operation
In the winter months, the outside air is colder. The temperature at a depth of two meters is higher than the surface temperature, so when cold air from outside circulates through underground pipes, it heats up. The hot air reaches the house, reducing the temperature gradient, allowing the heating to be connected at a lower temperature or even not to be used.
Summer operation
During summer, the air temperature is higher than the temperature under the ground. Therefore, when the air passes through the pipes, it gives up heat to the earth and cools down, arriving at the house several degrees cooler, creating a comfortable environment.
Soil thermal behavior
The subsoil, due to its large mass, maintains much greater thermal stability than the atmosphere throughout the year, which avoids peaks in cold and heat. Therefore, in summer, when it is hot outside, the underground remains at cool temperatures. On the other hand, in winter, when the outside temperature drops a lot, the underground remains warm or at least warmer than the outside.
This stability, however, is not uniform. It increases progressively, with the differences between summer and winter becoming smaller as the depth increases. It is estimated that around 10 or 15 meters deep the temperature is practically constant throughout the year. At depths of around 2 meters, we have already found functional temperature values close to the well-being values (18ºC – 24ºC) of homes.
Another thermal characteristic of the subsoil is its difference in relation to the external air temperature. Thus, after the hot months, when the cold days begin, much of the underground will still maintain a greater proportion of relative heat than the air. Likewise, when the hot days begin, the underground still maintains a greater coolness, a result of winter. This is due to the large amount of mass that the subsoil has, which means that it takes much longer to gain or lose heat compared to the air. This is the characteristic of a large thermal warehouse that Provençal or Canadian wells take advantage of.
Parts of Canadian Well Building Systems
Provençal or Canadian wells have the following parts:
Air capture point
This is the point at which the system takes in air from outside. This intake must be located slightly elevated (1m or 1,5m) to avoid capturing contaminated air. For this same reason, areas are chosen where the air keeps moving, avoiding depressions where the air stagnates.
These two measures are taken to avoid, above all, the capture of radon gas. Radon gas is a radioactive gas that is generated naturally throughout the Earth's crust, although with greater intensity in volcanic and granite areas. In high concentrations, it is harmful to health, so it should be avoided. As it is heavier than air, it tends to accumulate in depressions and holes when there are no air currents that can disperse it. Proper placement of the external air collector, together with the tightness of the system that prevents this gas from infiltrating inside the pipes, prevents contamination of this type of gas from affecting Provençal or Canadian wells.
The entrance must also have a grate that makes it impossible for insects, rodents or any other animal that could nest inside it or deposit excrement and dirt that could contaminate the system to access the system.
Filters
They are responsible for purifying the air and, therefore, preventing dust and dirt from entering the ducts.
Heat exchanger
It is the element that transfers heat from the ground to the air. Ultimately, this is buried piping. The length and diameter of this duct may vary depending on aspects such as the depth and nature of the terrain, the power of the element that sucks the air, thermal needs, etc. Of capital importance is the nature of the terrain and its ability to transmit heat (thermal conductivity). For example, dry sandy soils transmit heat worse than clayey ones. Soil moisture is also very important, since soil soaked in water, regardless of its composition, will have a great capacity to transmit heat, as water, in itself, has this capacity.
The longer the tube length, the more air-to-ground heat transfer will occur. The most used values vary between 10 and 100 meters in length. For the pipe diameter, recommended values vary between 20 and 40 cm in diameter.
The conduit or pipe must be waterproof and watertight, smooth, mechanically resistant to pressure and deformation of the ground. It must also resist corrosion. Finally, it must have good thermal conductivity (that is, it must allow heat to pass through itself or, in other words, it must be the least thermal insulator possible) to allow heat transfer between the ground and the indoor air. of the piping.
This piping should also have a slight slope. This is necessary because, at certain times of the year, condensation may occur inside the pipes. For example, in the summer, in the moments before a storm, hot, humid air can enter the exchanger piping. In the exchanger, when there is a drop in air temperature, condensation will inevitably occur. To avoid the accumulation of water in the pipes, they are placed with a certain degree of inclination, which will cause them to fall by gravity to a drainage point. If this element is not considered, nor are filters included, the accumulation of dust with organic matter and humidity would lead to the proliferation of fungi and bacteria.
The shape of the exchanger can also be varied, adapting to the available terrain and thermal needs. Thus, there are several designs, such as one in which the interchange conduit surrounds the residence, taking advantage of its perimeter, or those that are located concentrated in a quadrangular area of land adjacent to the house, and in which the pipes acquire different arrangements (pipes in parallel in the form of a grid, serpentine tube, etc.).
Drainage point
The water condensed in the pipes, due to the slope, goes to the drainage point where it is eliminated from the system.
Air circulation element
The air needs an element that propels it and circulates it through the buried pipes. At this point, and depending on what you want to achieve, active (mechanical) or passive elements (solar chimney) can be used.
As an active element, it can be a small fan or extractor of suitable power that sucks the air from the pipes and circulates it.
As a liability, there is the possibility of using domestic solar chimneys. In this mechanism, the sun heats the chimney and the air it contains, which causes it to become lighter, rise and exit through the upper opening. This creates a depression at the base of the solar chimney, in other words, a “lack of air” that causes a current towards the chimney. If the solar chimney is placed appropriately, it is possible for this suction effect to circulate air in the buried pipes of the Provençal well. This system can be effective during the hot months, in which the Provençal well is used for cooling. However, its use will not be convenient in winter under this scheme.
In any case, mechanical extractors and solar chimneys are not mutually exclusive and can complement each other perfectly to obtain greater savings.
The air tempered by Canadian Provençal wells can be connected to the residence's ventilation system. In this case, the well outlet is connected to the well's air intake. Its use with dual flow and heat recovery systems is also compatible.
Advantages of Canadian Wells
Canadian and Provençal wells, as they are an ecological, natural and low-consumption system, have a series of advantages that can be summarized in the following points:
- Less investment: They require a much smaller investment than a conventional reversible air conditioning system. Furthermore, if they are installed when the house is built, costs are reduced even further.
- Low energy operation: Its operation requires very little energy, spending is limited to operating the air extractor, when available.
- Reduced maintenance: Maintenance of Provençal or Canadian well construction systems is reduced, limited to cleaning the piping with suitable cleaners if necessary, changing the filters periodically, purging the condensate deposit, if any, and minimal maintenance of the air thrust system.
- Natural and ecological system: By using a local, abundant and completely natural resource, you avoid activating the entire chain of environmental impact acts that involve bringing artificial air conditioning equipment from afar, as well as, above all, the energy or fuels needed to do so function, all to achieve the same effect that is achieved with a Provençal well.
- Healthy for the inhabitants: Maintains a good level of air renewal, whilst also maintaining a healthy level of humidity (unlike many air conditioning systems that dry out the air too much).
Canadian well performance in summer and winter
Provençal/Canadian well construction systems, in themselves, are very efficient in cooling during the summer, and can perfectly replace conventional air conditioning systems. The comparison of energy expenditure between Provençal wells (a low-consumption extractor when the extraction system is mechanical) and the large consumption of conventional air conditioners clearly tips the balance in favor of the former.
In winter, however, wells may be insufficient on their own to provide the heat needed to air-condition a building, depending on the latitude. However, they can offer very important pre-heating of the air, which will result in substantial savings, as the thermal jump that the artificial air conditioning system will have to provide will be reduced. In high-altitude tropical areas, for example, where the nights are cold and the days are temperate or hot, the situation may be different. In winter, in areas close to the poles, they are effective on their own in keeping buildings that are unoccupied in winter defrosted.
The images in this article were taken from: angelsinocencio.com.
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