Comparative Energy and Cost Analysis Between Conventional HVAC Systems and Geothermal Heat Pump Systems.

摘要

To sustain the United States current affluence and strength, the U.S. Government has encouraged energy conservation through executive orders, federal and local laws, and consumer education. A substantial reduction in U.S. energy consumption could be realized by using geothermal heat pumps to heat and cool buildings throughout the U.S., though initial installation cost are a deterrent. This thesis uses Monte Carlo simulation to predict energy consumption, life cycle cost and payback period for the vertical closed-loop ground source heat pump (GSHP) relative to conventional heating ventilation and air conditioning (HVAC) systems: air-source heat pumps (ASHP), air-cooled air conditioning with either natural gas, fuel oil, or liquid petroleum gas furnaces, or with electrical resistance heating. The Monte Carlo simulation is performed for a standard commercial office building within each of the 48 continental states. Regardless of the conventional HVAC system chosen, the simulation shows that for each state the GSHP has the highest probability of using less energy and having a lower operating and life cycle cost than conventional HVAC systems; however, initial installation cost are typically twice that of conventional HVAC systems and payback periods vary greatly depending on site conditions. The average 50th percentile GSHP payback period in the U.S. was 7.5 years compared against the ASHP and 9.2 years compared against the air-cooled air conditioning with natural gas furnace. However, these values vary greatly depending on location and are most sensitivity to ground thermal conductivity, utility prices, and HVAC efficiency ratings. Under the right conditions, payback for geothermal heat pumps can be much shorter and the model developed in this research can help predict energy savings and payback periods for a given site.