Session: 02-03: HVAC System Analysis I

Paper Number: 130562

130562 - Techno-Economic and Environmental Performance Comparison of Different Systems for Space Heating Systems in Cold Climates – Case of the Bow Valley Municipalities 

Abstract: 

Meeting the stringent emission reduction targets set by several nations to minimize atmospheric greenhouse gases requires a significant shift in the way energy is generated and used. Shallow geothermal has the potential to meet space heating and cooling needs with significantly higher efficiencies and minimum greenhouse gas emissions. In this study, the potential for shallow geothermal systems in the Bow Valley region of southwestern Alberta, Canada, is investigated. The energy use of three building types, a duplex building, an apartment building, and a hotel, was determined through building energy modelling in BEopt^TM. The derived building loads were used to size the required heating systems for each of the building types. The potential to meet the building energy loads with a forced air furnace, an air source heat pump (ASHP), a ground water heat pump (GWHP), a ground source heat pump (GSHP), and an electric resistance heater. For forced air furnaces, three models of furnaces available on the market were used that is high-efficiency (95%), mid-efficiency (80%), and low-efficiency (60%) were used for comparison purposes with the heat pump and electric resistance heating. To properly size the heat pump systems, realistic input data was used, including the location-specific ambient conditions, the building energy loads, and the local geological information. In terms of geology, the ground thermal properties were calculated based on soil composition using empirical equations from literature, and underground water flow rates were gathered from available databases on pump test results of water wells. Energy modelling results give heating needs of 0.54 GJ/m², 0.35 GJ/m², and 0.13 GJ/m² for a 157 m² duplex house, 1100 m² apartment building and 10,125 m² hotel building. For these energy requirements, heating systems were designed for each of the building types and environmental and economic performance was evaluated. For each building type, the GSHP used the least amount of energy, followed by the GWHP, cold climate ASHP, conventional ASHP, electric resistance heating and gas furnaces. Following the energy use, the CO₂ emissions are in line with the energy use of each heating system and size type of building. The GSHP gives the least CO₂ emissions, considering the emission intensity of the electricity grid. For the duplex, the emissions are 44 tCO₂, 58 tCO₂, 72 tCO₂, 149 tCO₂, 145 tCO₂ and 289 tCO₂ for the GSHP, GWHP, cold climate ASHP, ASHP, electric resistance, and the high-efficiency gas furnace, respectively. The emissions follow the same trend for the apartment building and hotel but are higher given the large floor area of the two. The economics of each system is significantly influenced by location, natural gas prices, and available incentives, among others. Compared to natural gas heating with a high-efficiency furnace, the simple payback period is in the range of 15 – 40 years for GWHP and GSHPs, while it is in the range of 15 – 30 years for ASHP and cold climate ASHPs if space cooling is not considered.  Installations of air conditioners in Alberta has increased significantly over the past 20 years, so if space cooling is considered, payback periods reduce by 10-15 years for all heat pump based systems.

Presenting Author: Amirhossein Darbandi University of Calgary

Presenting Author Biography: Amirhossein received his Bachelor of science degree in Mechanical Engineering from Sharif University of Technology in February 2021. He joined the Sustainable Thermal Energy Systems lab at Mechanical Engineering Department at the University of Calgary as a Master of Science student in January 2022. His research focuses on the thermal analysis and optimization of foundation heat exchangers for space heating and cooling in the cold climates where heating loads are significantly higher the cooling loads. He is developing energy efficient ground heat exchanger designs and solutions decarbonizing space heating in buildings.

Authors:

Amirhossein Darbandi University of Calgary
Isabella Castaneda Arias University of Calgary
Max Holm-Radford University of Calgary
Aleksandra Govedarica University of Calgary
Roman Shor University of Calgary
Aggrey Mwesigye University of Calgary