Using geothermal energy in enhancing all-air HVAC system performance - Case study, thermal analysis and economic insights

The background is the same for addressing the twin challenges of attaining thermal comfort and concurrently reducing energy use and CO₂ emissions. As a safeguard against worsening contamination, combining geothermal energy with an All-Air Heating, Ventilating, and Air Conditioning system (HVAC) with 100 % fresh air intake is also crucial in the context of the lessons learned from the COVID-19 pandemic. As a result, this study suggests using geothermal energy as a backup source to run a typical All-Air centralized HVAC system. The resulting system is referred to as a combined system from now on, and its primary goals are to lower the amount of operating energy needed while being environmentally and financially sound. In this context, the creative way of combining the suggested geothermal duct with the All-Air HVAC system possesses various insights, as demonstrated by the thorough thermal analysis and related design. Strong conclusions were derived from a thorough case study focused on Lebanon: adding 100 % fresh air intake leads to an astounding yearly energy savings of 67 %, whereas configurations with 10 % and 30 % fresh air produced energy savings of 52 % and 36 %, respectively. In the study, a geothermal multi-duct system was also suggested and looked at. The research revealed that the 311-m length of the single geothermal duct connected to a pressure of 7000 Pa was reduced to 210 m and the pressure drop was lowered to 140 Pa when a geothermal multi-duct system was employed. Furthermore, as the computed payback period makes clear, the integrated system presents an appealing chance to drastically cut resource usage during energy consumption, lower CO₂ emissions, and provide 100 % fresh air circulation.