Evaluation of Low Temperature Ground Coupled Vertical Heat Exchanger in South Louisiana

Geothermal energy is a clean and sustainable form of energy. A shallow geothermal heat exchanger system with a vertical closed loop uses the temperature difference between the atmosphere and the soil to heat and cool buildings. In this paper a four-story building in New Orleans was evaluated for the potential use of geothermal energy through the building's foundation piles. Among its 145 driven piles only 16 piles were selected as energy piles. Using industry popular GLD 2012 software it was found that the 16 energy piles with a length of 24.38 m each altogether can extract a maximum of 29.31 (kW/hr) cooling load and 26.93 (kW/hr) heating load. This energy is equivalent to 19.9% of the total cooling demand and 68.12% of the total heating demand of the entire building. Using economic and environmental impact analysis it was found that, if the building only uses geothermal energy for its Heating, Venting and Air Conditioning (HVAC), it will be at least 13 times less costly than using natural gas or electricity only for heating and cooling. In this paper, research was done in sensitivity analysis on pile diameter, concrete thermal conductivity, soil thermal conductivity, soil temperature, U-tube diameter and U-tube flow rate. By varying those parameters, the total pile length needed was calculated if total HVAC demand was met by using geothermal energy.