Author/Contributor: Coulomb GeoExchange Inc., Zu House
Alberta Context:
This study compares the performance of ground source heat pumps (GSHP), air source heat pumps (ASHP), and natural gas furnaces under base code and high-performance building envelope designs.
The study was completed on a three-suite residential home retrofit in Edmonton, Alberta. The owners wanted to make an informed decision regarding the costs, emissions impacts, and efficiencies of various heating and cooling systems for each building envelope design as they explored different ways to retrofit. The home is modelled under both a standard building code and an upgraded insulation design. However, the home is expected to proceed with the high-performance insulation design.
Summary:
This study highlights key comparisons between Ground Source Heat Pumps (GSHPs) and Air Source Heat Pumps (ASHPs) across two building envelope designs and discusses the environmental impact, costs, and Albertan electrical grid sustainability.
An important part of this analysis is the total cost of ownership, as well as co-benefits such as risk mitigation. Implementing a GSHP, particularly with upgraded insulation, requires significant upfront investment. While natural gas systems offer the lowest initial costs, the long-term benefits of GSHPs, such as lower operating costs, make them more feasible over time.
The higher costs associated with GSHPs are likely more inflated due to the early adoption phase of this technology. As technology advances and the adoption of GSHPs increases, these costs are expected to decrease, making GSHPs more affordable.
“When comparing alternative forms of electrified heating and cooling, there are many aspects to consider. The study’s conclusions are listed below:
- Environmental Impact: After completing the analysis for this report, the system with the lowest CO2 emission (with and without the addition of solar) is the ground source heat pump (with upgraded insulation). Please note that the annual grid emissions for the ASHP alternatives are relatively similar to the natural gas heating alternatives; however, ASHPs are more efficient. Natural gas furnaces can never be 100% efficient, but a heat pump can be more than 100% efficient because it is not generating heat but instead is transferring heat from one place to another. ASHPs can be anywhere from 200% to 400% efficient, depending on outdoor weather conditions and heat pump design. GSHPs have high efficiency throughout the year thanks to stable ground temperatures.
- Capital Cost: The natural gas system option has the lowest upfront cost.
- Operating Costs: The least efficient methods of electrified heating (without additional insulation) offer the highest return on investment. This result is due to the increase in the allowable size of the solar array and the high export rates available in the summer months (while the majority of the energy is consumed at a lower rate in the winter months).
- Grid Sustainability: The ground source heat pump system is the most sustainable option for Edmonton’s grid. Unlike air source heat pumps (ASHP), which require full backup heating systems in winter, GSHP systems only need smaller supplemental heating systems. Additionally, GSHPs consume less power overall, reducing strain on the city’s grid infrastructure.
- Solar Roof Area: The electric vehicle market is expanding, and many homeowners are installing additional solar panels to power their electric cars. Due to the efficiency of GSHP, the house will require less solar panels (when compared to an ASHP) allowing room to expand the solar array to cover the energy requirement of future or currently owned electric vehicles.
- Solar Policies: Currently, the solar policies in Alberta strongly incentivize solar production. These policies may not last forever once the grid becomes overwhelmed. It is plausible that policies will incentivize a reduction in CO2 usage over solar production in the future. Since the majority of the energy used to heat the house lies underneath the property, the GSHP offers a better electrified heating solution to hedge policy changes.
- Back-up Power: The backup power requirements for a GSHP system are approximately ¼ to ½ of an ASHP system on the coldest days of the year. This can be especially beneficial if homeowners choose to install backup batteries, as it extends the time a home can function during grid outages. In emergency situations, this advantage could be crucial in preventing water lines from freezing while waiting for power to be restored.
- Electrified Heating Public Perception: The most efficient way to heat and cool a house is a ground source heat pump. In Alberta’s climate, ASHPs are a less efficient form of electrification due to their higher electrical demands and associated CO2 emissions, particularly in colder conditions. To truly reduce environmental impact and set a standard for how homes should be built, GSHPs provide the best solution.
Although the addition of upgraded insulation and a GSHP have higher upfront costs and lower operating income, these upgrades are recommended due to the reduced emissions, grid sustainability, reduced solar roof area requirements, reduced utility policy change risks, backup power requirements and public perception of electrified heating; it is recommended to implement a ground source heating system for this home.” – p. 11 (Alternative Heating Feasibility Study)
Read the full report here.
