So what do homeowners and builders need to know about geothermal passive energy systems?
First some basic facts about the Earth as an energy source.
Our planet’s structure consists of several distinct layers formed over time. The heaviest chemical elements can be found at the centre with the lighter elements more concentrated at the surface. There are three distinct layers: first the crust which contains 1% of the Earth’s total volume. Next, the mantle which constitutes 84% of the total planetary volume. And finally, we get to the core at 15%.
At the surface, the temperature of the crust varies, depending on the climate, time of year, current weather conditions and so on. Go down 1.5 to 4.5 meters (5 to 15 feet), however, and you find temperatures that are fairly constant: warmer than the air above it in the winter, and cooler in the summer.
What’s the reason for the heat? If you build a mine that descends thousands of meters into the ground one thing you note right away. The farther down you go the hotter it gets. The source of that heat lies in the mantle which averages temperatures between 500 and 900 Celsius, (932 to 1,652 Fahrenheit) degrees. Now add to that the heat from the Sun which can penetrate the Earth’s crust to a degree as well creating a crust sandwich surrounded by these two energy sources.
A passive or low-temperature geothermal energy system takes advantage of the constant temperature found just a few meters below the surface. To harvest the heat or cooling that comes from this source developers can install underground pipes and use this temperature differential to advantage. The reason these systems are referred to as passive is because they are not producing heating or cooling, but instead are just taking advantage of the what is underground.
How does a passive geothermal system work? It consists of three main components:
A loop is a series of pipes installed in a building or home that run from underground to above ground within the structure. These pipes are filled with a non-freezing fluid that acts as an energy transfer medium, picking up the heat from underground in the winter, and conversely picking up the cool from underground in the summer. It works best in a building that is properly insulated.
Also known as a ground source heat pump, its main function is to transfer geothermal energy from the loop into the distribution system. Located inside the building it circulates the liquid in the pipes. The pump requires an electric power source but the savings derived from the passive geothermal system more than makes up for this energy requirement. Based on existing operating systems, home and building owners can see as much as two-thirds energy cost savings when this type of heating and cooling system is up and running.
The distribution system refers to the ductwork within a home or building through which the loop runs. In making the decision to install a passive geothermal energy system or not there are additional considerations.
Once you have decided that a passive geothermal system is something that makes sense for you, it will reliably serve your heating and cooling needs with minimal maintenance for decades. Another form of renewable energy worth considering!
