Geothermal Energy

By admin at 3 January, 2009, 4:20 am

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Geothermal Energy – Energy produced by the internal heat of the earth; geothermal heat sources include: hydrothermal convective systems, pressurized water reservoirs; hot dry rocks; manual gradients; and magma. Geothermal energy can be used directly for heating or to produce electric power.

Geothermal Heat Pump – A type of heat pump that uses the ground, ground water, or ponds as a heat source and heat sink, rather than outside air. Ground or water temperatures are more constant and are warmer in winter and cooler in summer than air temperatures. Geothermal heat pumps operate more efficiently than “conventional” or “air source” heat pumps.

Heating Degree Day(s) (HDD) – The number of degrees per day that the daily average temperature (the mean of the maximum and minimum recorded temperatures) is below a base temperature, usually 65 degrees Fahrenheit, unless otherwise specified; used to determine indoor space heating requirements and heating system sizing. Total HDD is the cumulative total for the year/heating season. The higher the HDD for a location, the colder the daily average temperature(s).

Heat Pump – a refrigerant-based system that provides both heating and cooling and is more energy efficient that electric resistance heating. Both air sources units and geothermal units have back up energy (usually electric resistance heating) to provide space heating when temperatures drop below freezing.

Heat Recovery Ventilation (HRV) – A device that captures the heat from the exhaust air from a building and transfers it to the supply/fresh fresh air entering the building to preheat the air and increase overall heating efficiency.

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