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RETScreen® Ground-Source Heat Pump Project Model
GSHP heating energy delivered
The model calculates the heating energy delivered (MWh) by the GSHP system. The summation
of the GSHP heating energy delivered and the supplemental energy used equals the building's
heating energy demand calculated in the Heating and Cooling Load worksheet.
Units switch: The user can choose to express the energy delivered in different units by selecting
among the proposed set of units: "GWh," "Gcal," "million Btu," "GJ," "therm," "kWh," "hp-h,"
"MJ." This value is for reference purposes only and is not required to run the model.
Seasonal heating COP
The model calculates GSHP system seasonal heating COP. This value takes into account
parasitic energy used by circulating pumps and energy used by well pumps.
Cooling
Electricity used
The model calculates the electricity used (MWh) by the heat pumps to meet the heating
requirements of the building. The "Electricity used" value includes the energy used by the heat
pumps and the parasitic energy used by the circulating pumps for the ground loop in horizontal
and vertical systems. For groundwater systems, the electricity used also includes the building
loop circulating pumps power consumption and the electric energy required for the water well
pumps. In all cases, the circulating pump power is assumed to be 17 W for each 1,000 W of
capacity used by the heat pump system. The water well pumping power is calculated according
to the pumping depth specified by the user.
This value is dependent on the building energy demand but also on the selected "Average heat
pump efficiency." This value is transferred to the Cost Analysis worksheet where it is used to
calculate the GSHP system annual energy cost.
GSHP cooling energy delivered
The model calculates the cooling energy delivered (MWh) by the GSHP system, including the
supplemental heat rejection equipment. This value should be equal to the building's cooling
energy demand calculated in the Heating and Cooling Load worksheet. The model does not
consider any type of free cooling that could be used when estimating the cooling energy
delivered. Free cooling can sometimes be accomplished by using cool outside air or cool ground
loop fluid to offset the building's cooling demand without using the heat pumps directly.
Units switch: The user can choose to express the energy delivered in different units by selecting
among the proposed set of units: "GWh," "Gcal," "million Btu," "GJ," "therm," "kWh," "hp-h,"
"MJ." This value is for reference purposes only and is not required to run the model.
GSHP.21