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Economics - Operating Cost Summary

Use the peak heating and cooling loads, utility rates, and weather data (based on location) to calculate the estimated cost of operation for the GSHP system and compare it to other conventional heating and cooling systems.

Technologies to Compare

Select the conventional heating and cooling system(s) for direct comparison against the operating cost with a new GSHP system.

System Efficiencies

Specify the efficiency of the conventional heating and cooling system(s) selected for direct comparison against the operating cost with a GSHP system.

Heating

Resistance (COPh): The average annual COP for the electric resistance-based heating system. COPh is defined to be the heating energy delivered by the system (Btu) divided by the energy consumed to provide such heating (Btu) on an annual basis. For resistance heat, the amount of heat energy delivered is equal to the amount of energy consumed, giving the system an annual COPh=1.00, which applies to any electric resistance-based heating system.

ASHP (HSPF): Specify the rated efficiency of the air-source heat pump (ASHP) system in the heating mode on an annual basis. Heating Seasonal Performance Factor (HSPF) is defined to be the heating energy delivered by the system (Btu) divided by the energy consumed to provide such heating (Whr) on an annual basis. The HSPF reflects the efficiency level of the equipment, the average heating season outdoor air temperatures, and the use of auxiliary resistance heating for extreme outdoor air temperatures (IGSHPA 2009). Actual HSPF values exceeding 7.0 are not uncommon when ASHPs are used in warmer climates. Actual HSPF values below 5.0 are not uncommon when ASHPs are used in cold climates. Actual HSPF values can be drastically different from the rated values after several years of ASHP equipment operation due to degradation of the outside coil over time.

Natural Gas (AFUE): Specify the rated efficiency of the natural gas-fired furnace or boiler system on an annual basis. Annual Fuel Utilization Efficiency (AFUE) is defined to be the energy delivered (Btu) divided by the fuel energy consumed through combustion (Btu) for the entire heating season. AFUE is expressed as a percentage and is always less than 100%.

Propane (AFUE): Specify the rated efficiency of the propane-fired furnace or boiler system on an annual basis. Annual Fuel Utilization Efficiency (AFUE) is defined to be the energy delivered (Btu) divided by the fuel energy consumed through combustion (Btu) for the entire heating season. AFUE is expressed as a percentage and is always less than 100%.

Fuel Oil (AFUE): Specify the rated efficiency of the fuel oil-fired furnace or boiler system on an annual basis. Annual Fuel Utilization Efficiency (AFUE) is defined to be the energy delivered (Btu) divided by the fuel energy consumed through combustion (Btu) for the entire heating season. AFUE is expressed as a percentage and is always less than 100%.

Old GSHP (COPavg): Specify the average annual heating COP for the old GSHP unit to be replaced. COPavg is defined to be the heating energy delivered by the system (Btu) divided by the energy consumed to provide such heating (Btu) on an annual basis.

Table Icon Click on the Table Icon to view typical efficiencies of various gas-fired and oil-fired heating systems.

For more information on heating system efficiency, refer to Section 1.2.3.1 (Chapter 1, pages 11-13) in IGSHPA's Ground Source Heat Pump Residential and Light Commercial Design and Installation Guide.

Cooling

A/C (SEER): Specify the rated efficiency of the central air-conditioning system on an annual basis. Seasonal energy efficiency ratio (SEER) is defined to be the heat energy removed by the system (Btu) divided by the energy consumed to provide such cooling (Whr) on an annual basis. Air-conditioners and ASHP equipment are rated based on their seasonal cooling efficiencies and a minimum SEER value of 12 is required by the Department of Energy. Actual SEER values can be drastically different from the rated values after several years of equipment operation due to degradation of the outside coil over time.

ASHP (SEER): Specify the rated efficiency of the air-source heat pump (ASHP) system in the cooling mode on an annual basis. Seasonal energy efficiency ratio (SEER) is defined to be the heat energy removed by the system (Btu) divided by the energy consumed to provide such cooling (Whr) on an annual basis. Air-conditioners and ASHP equipment are rated based on their seasonal cooling efficiencies and a minimum SEER value of 12 is required by the Department of Energy. Actual SEER values can be drastically different from the rated values after several years of equipment operation due to degradation of the outside coil over time.

Old GSHP (EERavg): Specify the average annual cooling EER for the old GSHP unit to be replaced. EERavg is defined to be the cooling energy removed by the system (Btu) divided by the energy consumed to provide such cooling (kWh) on an annual basis.

For more information on cooling system efficiency, refer to Section 1.2.3.2 (Chapter 1, pages 14-15) in IGSHPA's Ground Source Heat Pump Residential and Light Commercial Design and Installation Guide.

Annual Operating Cost by Technology

View the annual heating and cooling costs for the GSHP system and for each of the conventional technologies selected for direct comparison for the building as specified throughout the project. Additionally, view how the annual heating and cooling costs for the conventional systems compare to the selected GSHP equipment. Annual heating and cooling costs depend on the specified efficiencies as well as the specified utility rates (entered on the PROJECT DETAILS page).

Annual Carbon Dioxide Emissions by Technology

View the estimated carbon dioxide emissions for the GSHP system and for the conventional heating and cooling system(s) selected for comparison.

Renewable Electricity: Check this box if the electricity for the project will be generated using renewable methods. Doing so ignores the carbon emissions associated with electricity consumption.

Electrically-driven heating and cooling systems (such as GSHPs, ASHPs, and central A/C systems) generate no point-of-use carbon emissions because no fossil fuel is burned to generate heat. However, using such a system will generate "upstream" carbon emissions as a by-product of the method used to generate electricity for the area. The actual amount of emissions depends on how the electricity is generated in the region of interest. The average amount of carbon emitted per kWh consumed is automatically calculated based on the mix of power generation methods for the region. For more information on carbon emissions by state and by electricity generation method, visit the Energy Information Administration website.

Combustion-based heating systems generate point-of-use carbon emissions as a by-product of the combustion process. Additionally, combustion-based systems generate "upstream" carbon emissions based on the electricity consumption of fans, induction motors, etc. required during system operation.