Optimizing Energy Consumption of Buildings Using Vertical Ground Source Heat Pumps (Case study: Tehran province)

Document Type : Original Article

Authors

1 Associate Professor, Department of new energies and environment, University of Tehran, Iran

2 Master of Science student, Department of new energies and environment, University of Tehran, Iran

Abstract

Introduction
Global energy demand is increasing for various reasons, including industrial development, economic growth, population growth, and lifestyle changes. On the other hand, fossil fuels cause many environmental problems, including global warming, climate change, ozone depletion, acid rain, water, and air and soil pollution. Incineration of fossil fuels since the beginning of the Industrial Revolution has emitted about 500 billion tons of carbon dioxide, about half of which remains in the atmosphere.
Material and Method
The faculty building consists of 4 floors. The total number of zones under the control of the faculty, which includes rooms, classrooms, workshops, laboratories, classrooms, toilets, and halls, is 152. The basement has 28 areas; the first floor has 39 areas, and the second and third floors have 34 and 51 areas, respectively. The peak load for the building's cooling needs during the year is 300 kW, and the maximum load required for heating is 155 kW. The faculty currently uses natural gas for heating and electricity for cooling systems.
In this research, a vertical geothermal system is designed for this educational building. The pipes of the vertical geothermal system are of the borehole type and are wound vertically into the ground from top to bottom.
By considering the standards of the systems and the fact that the maximum loads related to cooling and heating are 300 kW and 155 kW, respectively, the number of boreholes is 80. For this reason, the 80-hole geothermal heat pump system, which is also defined as standard in the software, is selected.
Results and Discussion
By installing the earth tube system in the building, the energy consumption of the building faces general changes. Figure 1 shows the energy consumption during a year while the geothermal system is responsible for providing the needs.
As shown in Figure 1, the energy consumption of the geothermal system consists of three sections: fans, pumps, and cooling and heating sections. This whole new system uses less electricity, and by using geothermal energy, natural gas consumption is reduced to zero.
 
Figure 9. Building energy consumption over a year (Earth tube system)
The highest consumption is related to fans, and the lowest is related to pumps, equal to 92.07 and 3.36 MWh per year, respectively. The total energy consumption of this scenario is equal to 615.36 MWh per year, which produces 372.91 tons of carbon dioxide. By comparing the traditional system to this novel system, it is clear that the use of geothermal green energy has led to a significant reduction in energy consumption and carbon dioxide emissions. Total energy consumption decreased by 77.89 MW per year and carbon production by 20.83 tons.
Conclusion
This study aims to optimize energy consumption and reduce carbon emissions of buildings in Tehran province using a geothermal system. Therefore, the building of the Faculty of New Sciences and
Technologies of the University of Tehran has been selected as the building under study. An 80-bore tube geothermal system installed vertically into the ground is designed for the building. The significant results of research and modeling are as follows:

By using geothermal energy to provide the heating needs of the building, consumption of natural gas is reduced to zero.
Replacing the traditional HVAC system and providing thermal comfort with the geothermal system is associated with a reduction in energy consumption of 77.89 MWh per year.
The use of renewable geothermal energy reduces carbon production by 20.83 tons per year.

Keywords

References

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Journal of sustainable Energy Systems
Volume 1, Issue 1
January 2022
Pages 15-31

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