The Biosphere's geothermal system

The Biosphere's geothermal system was installed during the museum's construction in 1995. It uses an open loop that originates in a water table, 90 metres below the surface, where the water temperature varies from 9–13 °C. At the time of its installation, this system was a highly advanced green technology. It allows significant energy savings, ranging from 30–40%. Given that the Biosphere is 5,623 square metres, this translates into major savings in the museum’s energy bill.

How it works

  1. Ground temperature is stable year-round (approximately 9 °C). Geothermics recover the ground's energy to heat or cool a building by means of an exchanger.
  2. A heat-conducting liquid (a mixture of water and glycol) leaves the building in a series of pipes underground, during which time it is heated (or cooled) by the ground's temperature

     

  1. The liquid circulating back into the building is therefore warmer (or cooler) and a heat pump subsequently extracts its heat (or coolness):
  1. The advantage of a geothermal system is that the liquid originating from the ground "pre-heats" (or "pre-cools") the air before the heat pump compresses the air at a required temperature. The energy increase makes the heat pump more efficiently: less energy is required in order to reach a certain temperature.
  2. The air is then distributed throughout the building by means of an air distribution system:

Types of geothermal systems

Two types of geothermal systems exist, the closed loop and open loop:

Closed loops:

These are the most widespread in Quebec, can last from 50–75 years, and have different configurations:

  • Vertical ground loop: This consists of pipes inserted into drilled holes in the ground. The pipes can descend to 15–100 meters underground. However, if the ground is very hard, a horizontal ground loop may be preferable.
  • Horizontal ground loop: The pipes are buried horizontally, usually at a depth of 2–2.5 meters. The network is spread across a much larger surface area.

Open loops:

It consists of collecting water from an underground source and extracting its heat using a heat pump. The water is subsequently returned to the ground source. New water is always pumped into the system when it is working. This type of installation has a shorter life span (about 15 years) since there is a risk of contamination in the pipes.

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