Geothermal energy is clean and renewable. It is generated from the energy stored in the earth, which is developed to meet household heating and air-conditioning needs.

Purchasing a geothermal system

A geothermal system is an energy-efficient solution that may be an excellent option to heat and air-condition a new home, replace an aging system or lower heating costs.

Benefits

  • Several systems in one: a geothermal system doesn’t only provide household heating. It may also be set up to air-condition your home and preheat the water in your water heater and pool.
  • Lower heating costs: the system will help you save up to 60% on heating costs as compared to a conventional electric resistance heating system.
  • Ecoresponsible heating: a geothermal system consumes less electricity and, by the same token, helps reduce energy demand in peak periods.
  • Sustainable solution: the system’s underground loop has a service life of over 50 years and the heat pump has a service life of approximately 20 years.
  • Easy maintenance: a geothermal system is just as simple to maintain as a conventional forced-air electric heating system combined with an air-conditioning unit.
  • Proven technology: the system has been tried and tested for over 30 years and the technology continues to evolve.
  • Certified system: the system’s certification by the Canadian GeoExchange Coalition is a guarantee of quality. For more information, download A Buyer’s Guide for Residential Ground Source Heat Pump Systems [PDF – 283 Kb].

Constraints

  • Cost: Several factors impact the price but, for an average home, the cost of the system will vary between $20 000 and $40 000.
  • Distribution system: installing a geothermal system in an existing house may require modifying the heating or air-conditioning distribution system (e.g. installing or modifying air ducts or adding baseboard heaters).
  • Drilling: the cost to install the underground loop varies according to the type of soil.

How geothermal systems work

Geothermal systems capitalize on the temperature just a few metres below the earth’s surface, which, in Québec, averages 10°C. In summer, the heat pump extracts warm air from the house, transfers it to the ground and then returns cool air to the house. In winter, the heat pump extracts the heat stored in the ground and transfers it to the house.

Three components of a geothermal system: a heat pump, an underground loop that warms or cools a circulating fluid, and a distribution system that circulates warm or cool air throughout the house

1. Heat pump

The heat pump is connected to the distribution system and transfers heat between the ground loop and the house. In winter, it concentrates heat from the ground loop and transfers it to the house. In summer, it sends heat from the house into the underground loop and cools the house.

2. Underground loop

In a geothermal system, the ground loop serves as the heat source and heat sink. The ground loop can be either open or closed.

Closed-loop system

In a closed-loop system, a fluid mixture of antifreeze and water circulates through the ground loop and heat pump.

Four types of closed-loop systems:

Horizontal loop
Vertical loop
Suitable for most average-sized lots, the vertical loop is the most common configuration.
Direct expansion
Developed in Canada, the direct expansion system is especially suitable for existing houses. It is adapted to tighter spaces such as those in urban areas because it does not require deep drilling, which can be carried out by a very small drilling machine. In a direct expansion system, a refrigerant fluid flows through copper piping buried approximately 30 m underground.

Lake or pond

Open-loop system

In an open-loop system, groundwater from a well serves as the heat source and heat sink. The pump draws water from the well and then extracts or transfers the heat (depending on the season) through a heat exchanger. The water is then discharged into the earth, usually through a return well.

3. Distribution system

The distribution system may be a central forced-air or hot water system or a hybrid system involving hydronic floor heating, for example. But only a system with air ducts can provide air-conditioning in every room. If your home is equipped with a hydronic system (radiant heating or other type of system), you must have air ducts installed for central air-conditioning.

Frequently asked questions

Can a geothermal system be installed only in a new house?

No. A system can be installed in an existing house. So it is an option that you may want to consider if you are planning to buy a heating and air-conditioning system to replace an old heating system. If your house already has a distribution system (ductwork), the work will be much easier and cheaper to do.

What is the payback period for a geothermal system?

As the capacity and thus the cost of geothermal heat pumps can vary from one house to another, the payback period also varies.

Factors that affect the payback period for installation of a geothermal system in a new or existing house:

  • System type and price and installation cost (including costs related to earth-moving work, limited access, etc., in the case of an existing house)
  • House size (the bigger the house, the bigger the savings on heating)
  • Quality of home’s thermal envelope
  • Age and type of existing heating and cooling system
  • Age and type of existing heating and cooling system

All these factors have an impact on the payback period for an investment in a geothermal system, keeping in mind that, for a typical house, you can expect to pay somewhere between $20,000 and $40,000.

Is it absolutely essential to have a forced-air system with a geothermal system?

No. A hot-water system can be used for radiant heating (or another system), but not for air-conditioning. Of course, you can have air ducts installed for central air-conditioning.

See also