How does geothermal heating work?

How does Geothermal heating and cooling work?

Geothermal heating and cooling system is one of the most efficient and environmentally friendly space heating and cooling systems available for residential and commercial buildings. In this article I am going to explain how does geothermal heating and cooling work. But before that let’s first see how does geothermal work and what is geothermal heating and cooling system?

What is geothermal heating and cooling system?

How does geothermal work? Geothermal works by using relatively constant temperature of soil or water located just below the earth’s surface (in the range of 45° to 65°F) to heat and cool our homes. It uses a geothermal heat pump system to either add or remove heat for our end uses, such as for space heating, space cooling or for water heating. The US Environmental Protection Agency (EPA) and the Department of Energy recommend the use of geothermal heating and cooling as a green technology to lower both energy costs and our dependency on fossil fuels. Now let’s see how does geothermal heating and cooling work.

How does geothermal heating and cooling work?

Geothermal heating and cooling system consists of three main parts – a geothermal heat pump, a series of ground loop pipes buried underground and a distribution system (a conventional duct system).

The heat pump unit is connected to a heat exchanger which has a series of ground loop pipes buried underground. The ground loop pipes are laid either in horizontal trenches below the ground surface if there is enough space or in a series of vertical boreholes which reach much deeper into the ground, where space is limited. The system takes advantage of the naturally occurring difference between the above-ground air temperature and the subsurface soil temperature to move heat from one point to another. The heat pump circulates a heat-conveying fluid (usually water/methanol mix) through the buried loop pipes that are in contact with the ground which allows the fluid to absorb heat from the surrounding earth or to remove heat from the warm air inside our homes for space heating or space cooling using a conventional duct system.

Now let me explain how does geothermal heating work.

How does geothermal heating work?

When the subsurface temperature is higher than the above-ground air temperature, the heat pump system moves heat from the ground to our homes via the circulating fluid through the buried loop pipes, effecting geothermal heating.

During this heating cycle the heat pump’s heat exchanger system pulls the heat from the fluid which is absorbed from the surrounding earth and distributes the heat as warm air throughout the house through the duct system. Thus the geothermal heating utilizes the earth as a heat source to obtain the heat. This is how geothermal heating works.

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How does geothermal cooling work?

For geothermal cooling or geothermal air-conditioning of our homes, the heat pump system operates in reverse of as explained under how does geothermal heating work. Here’s how does geothermal cooling work.

Geothermal cooling works on the same principle as our refrigerator does. Our refrigerator removes heat from its interior and transfers it to outside in the room where it is placed. During the cooling cycle, instead of absorbing heat from the surrounding earth, the circulating fluid through the pipes absorbs heat from the surrounding warm air inside our home. Once the heat is removed from the surrounding air, the air becomes cool and the cold air is distributed all over the house through the duct system for space cooling or air conditioning. The heat absorbed by the fluid from the surrounding air, is ultimately deposited into the earth or water source that serves as the system’s heat sink, or receptacle for heat energy. Thus geothermal system utilizes the earth as a heat sink to discharge heat for cooling our homes in summer.

For this cooling process the geothermal heat pump system requires a small amount of electricity.

You may also like to read this post: Is Geothermal Energy renewable or nonrenewable?

Frequently asked questions

Now that I have explained how does geothermal work for heating and cooling our homes let me also address some of the related questions often asked by the homeowners, intending to install geothermal system.

How efficient is geothermal heating and cooling?

The circulating fluid in the buried underground loop provides geothermal heating and geothermal cooling at a remarkably high efficiency throughout the year. The conventional HVAC system (Heating, Ventilation, and Air Conditioning) is not that efficient because air temperature varies a lot throughout the year. Geothermal heating can be up to six times more efficient in producing heat energy as compared to traditional systems. The system uses about 15% less electricity than conventional systems.

Although the geothermal heating system doesn’t get as hot as conventional boilers (regular boiler systems tend to operate at around 70-80°C whereas ground source heat pump systems normally operate at approximately 35-50°C) that doesn’t mean that you can’t get rid of the chill in winter if you have a geothermal system.

The geothermal heating and cooling system is designed to be highly efficient to maintain a comfortable temperature in your house or building throughout the seasons making your living environment more relaxing.

What are the benefits of geothermal heating and cooling?   

Geothermal heating and cooling system has several benefits over HVAC system. Some of the key benefits of home geothermal system are as follows.

Environmentally friendly

Geothermal system is one of the most environmentally-friendly and safe heating and cooling system for our homes. It doesn’t burn any fossil fuel and produce almost no greenhouse gasses that contribute to air pollution. Only a small amount of electricity is used by the system. In fact, U.S. Environmental Protection Agency recommends use of geothermal air-conditioning and geothermal heating as a green technology to lower our dependency on fossil fuels.

Highly cost-effective

Although the installation costs of geothermal system is quite high as compared to the conventional HVAC system, you can potentially save a significant amount (up to 60% annually) with this system in the long-run from savings in your utility bills. According to the US Environmental Protection Agency,  homeowners can save 40 to 60 percent on cooling and 30 to 70 percent per year on heating  by installing home geothermal system. This means that the system pays for its installation in about 7 to 10 years.

Reduces dependency on fossil fuels

Geothermal heating system pulls heat from the earth’s core where an unlimited amount of heat is continuously produced naturally. Since the heat is obtained without burning fossil fuels, the energy source is sustainable and will not run out and can be re-used multiple times. Hence geothermal system can reduce our dependence on fossil fuels, whose supplies are rapidly running out.

Low maintenance costs

Since geothermal heating and cooling system has few moving parts compared to other HVAC systems, its maintenance costs are much less. It only requires periodic check up and very little maintenance as compared to conventional systems.

Long lifespan

The average lifespan of a geothermal heating and cooling system is about 24 years which can even be extended upto 50 years with little maintenance over the system’s lifespan. The only part of the system that may need replacement sooner than that (may be after 20 to 25 years) is the heat pump, which can be replaced at a fraction of installation cost of the full system. On the other hand the lifespan of a conventional HVAC system is much less, which is between 13 and 15 years.

What is the geothermal heating and cooling cost compared to HVAC system?

The geothermal heating and cooling cost is initially about 40 percent more than a conventional HVAC system due to high installation cost of the system. The current average installation cost ranges between $10,000 to $30,000 depending on available land, type of soil, local climate, the type of heat pump to be used and the amount of digging and drilling required. For larger homes, geothermal heat pump system can cost as much as $30,000 to $45,000. Nevertheless, although the initial cost for installing a geothermal system is quite high, due to considerable savings in annual utility bills, the system can pay for its installation in about 7 to 10 years depending on the utility rates and the cost of installation.

Is geothermal heating and cooling worth it?

Since geothermal heating and cooling is a highly efficient system, the homeowners can enjoy the benefits of significant savings on their utility bills and keep their homes at a comfortable temperature year-round by this system, in an eco-friendly way. You can save about 30 to 70 percent per year on heating and 40 to 60 percent on geothermal air-conditioning by installing home geothermal system.

Can I put geothermal in an existing home?

The geothermal heat pump system can be easily included in an existing system if there is enough space in your utility room or basement to accommodate all the necessary components.

How much land do I need for geothermal system?

You will need about 400 to 600 feet of horizontal loops for each ton of energy required for heating or cooling. A mid-sized house, which usually requires 3 tons of energy, would need land to accommodate approximately 1200 t0 1800 feet of ground loop pipes.

Does geothermal increases home value?

Since geothermal system saves significant amount on utility bills and helps in eco-friendly living, it can raise a home’s value.  For example, with this system, the total savings may add up to $45,000 for a prospective buyer if he stays in his home for around 20 years.

You may also like to read this related post: Pros and Cons of Geothermal Energy

Conclusion

On going through how does geothermal heating and cooling work it would be evident that this heating and cooling system makes a great option for the eco-conscious homeowners. Geothermal cooling system is becoming increasingly popular in the US as people look for more efficient and environmentally friendly ways to keep their homes at a comfortable temperature year-round.

From the explanation of how does geothermal work it is apparent that it is more efficient when compared to traditional heating systems like furnaces, which have to burn fuels or use electricity in order to generate heat. Even in its cooling mode, the geothermal system is recognized for its efficiency.

As already explained in the post, the major factors behind the increasing popularity of eco-friendly geothermal heating and cooling system as an alternative to more conventional HVAC systems are – significant savings in energy bills, reduced maintenance costs, hedge against rising electricity prices and our reduced dependency on fossil fuels like oil and natural gas.

Environmental regulations are also giving more stress on the use of renewable energy sources in order to reduce carbon emissions and depletion of fossil fuels. This factor is also expected to have a positive impact on the increasing use of geothermal heat pump system for geothermal heating and geothermal air-conditioning of our homes.