Frequently Asked Questions (FAQ)

* Source: Airtechni and Geoconfort staff, Earth Energy Society of Canada, Hydro-Quebec and NRCan

FAQ > Questions related to earth energy concept

• How does an EE system use solar heat to cool a home?
  ACold is the absence of heat. In summer, heat from the building is transferred into the fluid used in the loop (by means of a compressor) and, as this fluid circulates, the heat is rejected (discharged) into the ground around the loop pipe. By transferring heat out of the building, this provides cooling and dehumidification.
• How can an EE system provide both heating and cooling?
  AIn winter, the system extracts heat from the ground, which is converted to warm air (or water) for space heating, water heating or radiant floor heating. In summer, the compressor puts heat from the building into the loop fluid, and this heat is ‘rejected’ into the ground outside to provide cooling for the structure.
• How does the EE system extract heat from frozen soil?
  AThe loop is buried below the frost line, and insulation is used to protect any section that may rise above the frost line (eg: as the pipe enters the building) to avoid freezing in winter.
  
  
• Can an EE system be used for anything other than heating and cooling a building?
  ATwenty percent of the average energy demand in a residential home is for water heating, and most units include a component to heat water for potable or sanitary use. Heat pumps can also be used to dehumidify indoor swimming pool areas, by controlling condensation with a minimum of ventilation and using the recovered heat in the main heating process.
• What happens if an EE system tries to extract too much heat from the ground?
  AWhen the loop cannot obtain sufficient heat from the ground, most systems include a back-up electric element to provide supplemental heat.
  
  
• Do EE systems have outdoor units?
  AThe ground loop is buried in the soil and enters the building through an underground penetration. There are no visual components outdoors.
  
  
• Can an EE system work with a diesel generator?
  AThe generator must be of sufficient capacity and have a constant voltage, to meet the electrical demands of the heat pump operation, including circulating pump for the loop and distribution pump for the hot air.
  
  
• What is the difference between an EE and an air-source heat pump?
  AAn air-source system is a similar concept to an EE system, but it extracts heat from outside air instead of from the ground. Winter air does not contain much latent heat, and the efficiency of an air-source unit drops significantly when outside temperatures drop below 0oC. The compressor in an air-source unit is located in the outdoor compartment, where it is noisy and exposed to weather elements. By comparison, an EE system is more efficient due to higher ground temperatures in winter, and the absence of any outdoor equipment makes an EE system quieter, more aesthetically pleasing and longer lasting.
• Can EE systems be used in commercial or industrial buildings, or in apartment or school?
  AResearch conducted for NRCan indicates that these applications are very cost-effective and offer high reductions of greenhouse gas emissions. Often, these applications offer a more balanced load profile than a residential home and, therefore, are less expensive for the heating or cooling supplied. More than half the EE systems installed in Canada are used in these applications.
• Can heating and cooling occur simultaneously in the same building?
  AEach heat pump unit can perform only one function at a time, but a larger building (with more than one unit) can provide heating to one spot and cooling to another. This is a common application in schools and other institutional facilities, which have a diverse load. The practice also increases the efficiency of the overall system because the heat removed from room A can be transferred to room B, reducing the need for the ground loop to provide both heating and cooling (and thereby reducing the total installed cost).
• Can an EE system provide heat recovery ventilation?
  ASome units integrate a HRV unit that can provide fresh air and enhance building comfort, and offer enhanced defrosting without creating negative pressure inside the building.
  
  
• Is the compressor in an EE unit the same compressor as in a refrigerator?
  AA refrigerator is designed to cool food by extracting heat from the package and transferring the warm air into the kitchen. An EE system can be reversed to provide cooling or heating, depending on the season. There are numerous compressors on the market, all of which use the same general principles, although the specific models used in an EE system are different from the kitchen appliance.
• Is there a national or local standard for the design and installation of an EE system?
  ADesign and installation are covered under national CSA standards C447 (commercial) and C445 (residential). As of March 2002, both applications are covered under the CSA C448 standard. EESC is not aware of any mandatory provincial regulations pertaining to EE systems, although some municipalities or regulatory agencies may have guidelines or rules which have an impact on the design or installation of EE systems.

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