Energy and structural performance of thermoactive piles in cold regions
The objective of this thesis was to develop and apply thermal and thermo-mechanical analyses to evaluate the structural and energy efficiency of a Geothermal Energy Pile Foundation System in cold regions. Such systems were used to re-harvest the buildings energy loss through their below-grade enclosures for providing heating and cooling energy demand. To investigate the energy performance of the below-grade envelope of a building in cold regions, a thermal analysis was carried out for an institutional building, the Stanley-Pauley Engineering Building (SPEB) located in the campus of the University of Manitoba. Knowing the amount of the annual heat dissipation from the sub-grade enclosure of the building to the ground, soil temperature increase was calculated. To efficiently harness the leaked heat from the basement, a geothermal energy system was proposed to be integrated to the foundation of the SPEB and the energy efficiency of such a system was assessed. In addition to the energy efficiency of the proposed system, the thermo-mechanical response of the proposed thermo-active foundation to the applied thermal and mechanical loads was also evaluated. Results showed that 8% of the annual energy consumption of the SPEB in terms of space heating was leaked into the ground. This energy loss increased the temperature of the soil underneath the building. Using the geothermal energy foundation system, the lost energy was aimed to be re-harvested. Results showed that the thermoactive foundation system could supply 4-15% of the building heating demand during Nov-Apr and 7-41% of the building cooling demand during May-Oct. It should be noted that application of such foundation system necessitated larger factor of safety effective on the allowable load.
Geothermal energy pile, Cold regions, Thermo-mechanical modeling, Thermal modeling, Energy loss