What is Geothermal Underfloor Heating?

Geothermal underfloor heating is a type of underfloor heating system that utilizes geothermal energy. An underfloor heating system is one that places the heat source under the floor of the house. Having a heat source under the floor of a room can more efficiently distribute the heat in the room than a more traditional heating system, where the heat source is in the room itself. Traditional heating systems create heat in one area, and use air currents to move the warm air around. Since warmer air rises, these traditional systems inevitably cause most of the warm air in the house to be concentrated up near the ceiling, where people living in the house can’t feel it. Underfloor heating systems provide a more optimal distribution of hot air, because the heat energy is distributed relatively evenly across the whole floor. Warm air rising off the floor cools as it rises, so there is much less hot air near the ceiling. Underfloor heating systems are also more comfortable than other heating systems because the floor is always warm in the home, so people with an underfloor heating system will not get icy cold feet in the winter.

Geothermal underfloor heating systems use energy from inside the earth. Only a few feet under the surface, the ground temperature is remarkably constant, from about 51 to 55 degrees Fahrenheit, even in winter. Geothermal heating systems can collect heat energy from under the ground, and concentrate it inside your house. They work in much the same way as a refrigerator, except in reverse. To understand exactly how a geothermal heating system works, you must first understand a few basic physical phenomena concerning heat energy and how it affects matter.

Every substance is made of tiny units called molecules, and kinetic temperature is the random motion of the molecules that make up a substance. The greater the average velocity of the molecules that make up a substance, the higher its temperature is. Even the molecules in solids are in constant motion, but their velocity is less than the average velocity in liquids, and the motion in liquids is less than the motion in gasses. Heat is transmitted between substances and objects when the molecules that make them up collide. When a fluid substance such as a liquid or gas is compressed, there are more molecules per unit volume, so, on average, there are more collisions between the molecules that make up the substance and the molecules that make up its container. Because of this physical phenomenon, known as Guy-Lussac’s Law, more heat can flow from the fluid to its container when the fluid is compressed.

In an underfloor geothermal heating system, a mixture of water and a chemical called a refrigerant are pumped around a loop of pipe that goes through the floor of the house and under the ground outside. The mixture is compressed to a liquid when it is under the floor of the house, and decompressed to a gas when it goes through the ground. This way, heat energy is drained out the mixture through the pipe under the floor, and absorbed into the mixture when it is under the ground outside, creating a net flow of heat energy from the ground to the inside of the house.