“Azure’s International AZ Awards recognize excellence and innovation in architecture and design, and celebrate the world’s best projects, products and ideas.”

This international design competition annually selects winners in the categories of design, architecture, landscape architecture, urban design, experiential graphic design, interiors, concepts, student work and social good/environmental leadership. The 2022 awards saw Toronto’s Mirvish Village redevelopment project winning in the Urban Design Vision category. Click here to read more about the Mirvish Village AZ Award.

Award-winning Redevelopment

Mirvish Village is rising on the site of ‘Honest Ed’s,’ a much-loved discount store that was at the heart of Toronto’s Mirvish Village neighbourhood for almost 70 years. The redevelopment is currently under construction and spans 4.5 acres, creating nearly 1 million ft2 of purpose-built rental housing and retail space.

Mirvish Village has a focus on sustainability and affordability. To achieve this, the redevelopment is incorporating a district energy system and micro-grid that will offer a resilient means of thermal energy, power, and emergency power, enabling the project to meet LEED platinum and the City of Toronto’s Tier 2 Toronto Green Standard requirements. 

HH Angus’ Role

Our Energy Division team worked closely with Creative Energy Developments to provide mechanical and electrical engineering services for the Village’s central utility plant, which includes a combined heat and power plant (CHP), a boiler plant, and a cooling plant. The CHP plant includes an 800 KW generator set with auxiliaries and heat recovery system. The generator is expected to run continuously to provide power to the complex.

Heat recovery consists of two systems: high temperature to provide heat to buildings, and low temperature to provide additional heating for a winter snow melting system and swimming pool heating. The boiler plant includes four condensing hot water boilers, with the option for two additional boilers in future. All boilers have an output of 3.1 MW.

The cooling plant includes two water-cooled chillers, operating at 1200 tons each. One is a magnetic bearing chiller with variable frequency drive (VFD), and the other is a centrifugal chiller with VFD. As well, two rooftop cooling towers at 1200 tons each have been installed. 

Central distribution piping from the plant will provide hot water and chilled water to multiple energy transfer stations, with heating, cooling, and domestic hot water heat exchanges for each building within the complex.

A photo-voltaic solar system will have a capacity of 103KW, 480V. HH Angus provided direction for locating the installation, coordinated with the PV supplier for modeling the panel direction and angle for optimal PV output, developed technical connection requirements with Toronto Hydro, and identified requirements for parallel generation with the central utility plant. Our scope also included developing thermal and electrical metering strategies within a microgrid system, and design of operation for gas-fired emergency generators in electrical peak shaving mode.

Rendering courtesy of Westbank Corp


Mirvish Village - AZ Awards | AZ Awards (azuremagazine.com)

“By addressing occupant well-being, energy and greenhouse gas reductions and decarbonization targets, the AEC industry can bring existing buildings into the future.”

Akira Jones’ keynote address kicked off a recent panel discussion on Smart Buildings: Now and Tomorrow, from Canadian Consulting Engineers (CCE).

According to Akira, Director of Digital Services at HH Angus: “Understanding the intersection of technology and the built environment to deliver better business outcomes and performance will be instrumental for engineers, architects, contractors, integrators and other professionals in the architectural, engineering and construction (AEC) industry to be successful. This understanding presents a fantastic opportunity for owners to leverage technology to modernize their buildings and assets. By addressing occupant well-being, energy and greenhouse gas reductions and decarbonization targets, the AEC industry can bring existing buildings into the future.”

The CCE event provided attendees with a forum for information, knowledge and practical advice on making the buildings, facilities and structures they design more economical for owners and safer and more functional for occupants.

The panel spotlighted key aspects of creating and managing smart buildings in a variety of settings including office, institutional, mixed use, industrial and retail. The discussion focused on topics such as: Emissions, Energy Efficiency & Sustainability, IoT, Security, Life Safety and Buildings/Construction ROI when it comes to issues pertaining to utility/energy management, security and emergency response.

For a video of the keynote address, click here.

To see the full panel of speakers, click here.

Akira Jones, P.Eng., LEED AP
Akira is Director of HH Angus’ Digital Services team, which specializes in BIM processes and software, 3-D scanning and Scan-to-BIM, the Internet of Things (IoT), digital twinning and Amazon Web Services cloud consulting. He is also a Mechanical Engineer with well over a decade of experience in the AEC industry.

Heat Pumps Reducing your Building’s Reliance on Fossil Fuels

In Part 1 (https://hhangus.com/heat-pumps-reducing-your-buildings-reliance-on-fossil-fuels/) of this series, we introduced the use of heat pumps for building heating and how they present an opportunity to mitigate the effects of climate change. In Part 2 (https://hhangus.com/heat-pumps-reducing-your-buildings-reliance-on-fossil-fuels-part-two/) we discussed the cost implications to owners and operators, as well as considerations, opportunities and risks present for heat pump heating and how to navigate them. In this final installment, we review refrigerant options and additional considerations impacting a building owner or operator’s decision to implement heat pumps, along with a summary of key take-aways.

When it comes to selecting a heat pump, the refrigerant will play a role in determining the operating temperature of the heat pump. This is critical to older buildings that require high temperatures for heating due to poor thermal performance of the building envelopes. It is important to consider that synthetic refrigerants such as R134A and R1243Zde, which are commonly used in commercial heat pump applications, have some limitations on their maximum operating temperatures. In addition, some of them have higher Global Warming Potential (GWP) as well as higher refrigerant costs. See Table 1.

Table 1 Refrigerant Selection Criteria, adapted from Emerson

Natural refrigerants, such as Ammonia (R717) and CO2 (R744), can achieve higher operating temperatures and have minimal/no GWP in addition to relatively lower refrigerant costs. However, the capital cost for machines using Ammonia (R717) and CO2 (R744) is generally higher than that of synthetic refrigerants. This is because these refrigerants operate at much higher elevated pressures (up to 2000~3000 PSI for CO2). See Figure 7. Piston reciprocating and screw compressors can be used for these machines. This can sometimes result in additional noise suppression requirements for certain projects that use these types of compressors. Natural refrigerants are typically used for industrial application; however, they are making their way to small scale applications. It is worth noting in the case of using ammonia as a refrigerant that, based on the refrigerant charge, there may be additional challenges such as code requirements for room construction and emergency refrigerants leak detection and evacuation.

Figure 7 Comparison of simple refrigeration cycles Subcritical R134a refrigeration and Transcritical CO2 cycle (CIBSE Journal)

Commercial heat pumps can provide hot water for heating to a maximum temperature between approximately 60 and 70°C (140 to 160° F), while industrial heat pumps can operate at temperatures up to 95°C (203°F). These differences in temperature limitations would have some effect on the maximum COP that these types of heat pumps can achieve. Some system designs can combine two refrigeration cycles, each having separate and different refrigerants: one is synthetic while the other is natural, resulting in the best of both worlds of cost versus efficiency.

One final item to consider is the phase out schedules of refrigerants. While many of the commercial synthetic refrigerants currently on the market do not have set phase out dates, it is possible that such refrigerants would fall under regulatory scrutiny that may require them to be phased out or replaced in the next 10 to 15 years. Natural refrigerants do not face such risks.


Other Considerations

Whole-building Energy Modeling

There are several other considerations that play a role in utilizing heat pumps for building heating. One of their main operational advantages is that they can provide heating only, cooling only, or simultaneous heating and cooling. It is easy to quantify the energy costs for heating or cooling using a heat pump as a dollar value per unit of heating or cooling. However, as previously noted, it becomes harder to quantify the benefits of a heat pump in a simultaneous heating and cooling scenario. At the design stage, a data-driven energy model of the building systems can help owners evaluate the true benefit of using heat pumps, especially for simultaneous heating and cooling, and a wide variety of modeling tools is available to engineers in this field. These tools can use real building heating and cooling load data to quantify the savings and operational advantages that a heat pump can bring when providing buildings with both heating and cooling at the same time.

Building Envelope

While not typically considered in the same context, the thermal performance of the building envelope is an important system to analyze and study along with heat pump technologies. Certain heat pumps can have limitations regarding the maximum supply water temperature (SWT) they can achieve. At the same time, the thermal performance of the building envelope defines the need for higher or lower SWT. For instance, high performance building envelopes enable the use of lower temperature heating systems to maintain comfortable temperatures indoors, which expands the list of heat pump technology options that can be used. It is important to note that, as technology improves, heat pumps are able to operate at even lower ambient temperatures and to produce even higher supply water temperatures. Consequently, it is possible to find heat pump products for most climates and buildings. However, there are undeniable synergies between high performance envelopes and heat pumps to achieve overall high building energy and carbon performance and, as such, these two energy conservation measures should be bundled whenever possible.

Geoexchange Systems

Tying heat pump systems to geoexchange systems can help heat pumps provide heating to buildings during peak winter days with no performance deterioration when compared to air source heat pumps (ASHP). Geoexchange systems utilize the ground as an energy source during the winter and as a sink in the summer. When coupling such systems with a heat pump, the caveat is to be able to accurately balance the thermal energy of the system across the seasons to avoid depleting the thermal source in the ground. This concept can be analogous to using the ground as a thermal battery that operates seasonally. This thermal battery charges during the summer where the heat pump cools a building and rejects heat to the ground, and in the winter the thermal battery discharges by acting as a heat source that provides thermal energy to the heat pump. In general, Thermal Energy Storage (TES) systems apply to refrigeration systems including heat pumps and can help in peak load management for building thermal loads; taking this into consideration when implementing heat pumps can result in both operation and economic gains.

Domestic Hot Water

One final consideration is that heat pump systems can be utilized for domestic hot water heating applications. Such integration can be relatively easy to implement from a design standpoint and can often result in capital and operational cost savings on domestic hot water heating equipment.

Simultaneous Heating and Cooling

Heat pumps can provide heating and cooling at virtually any time of the year, which provides the ability to control space conditions independently from each other. This allows for some zones to be in cooling mode while other zones are in heating mode, leading to increased occupant control and comfort. This is particularly important during shoulder seasons where some zones might require cooling (e.g. south facing), while other might require heating (e.g. north facing). This is a benefit of heat pumps compared to systems like a conventional 2-pipe Fan Coil systems with a Chiller and Boiler plant, where a seasonal changeover must be performed, and limits all the fan coils in the system to be in either cooling or heating mode.

The Bottom Line

Heat pumps can meet increasing space cooling and heating demand in many regions around the world, including North America. Over the next few decades, energy consumption for space heating and cooling are expected to converge. See Figure 8. Heat pumps would emerge as a linking technology between building heating and cooling energy around the world.

Figure 8: Building Final Energy Consumption Space Heating and Cooling, 2020 to 2050

Heat pumps can be deployed in urban, suburban, and rural areas with new heat pump solutions that are emerging rapidly and being deployed on a larger scale. This trend is expected to continue over the next couple of decades. Higher efficiency heat pump machines are already being utilized across the board. However, there will be specific technologies and designs that are tailored to certain buildings or climate characteristics. Air source heat pumps can be successful in low carbon buildings in most climates, while ground-source heat pumps would work better in very cold climates or in buildings that have space restrictions, such as older buildings. Selecting the right technology for the right application remains critical to the success of heat pumps in terms of cost and emissions reductions.

For more information about heat pump technology or to speak with one of our energy specialists, contact us at lowcarbon@hhangus.com or contact one of the authors of this article below.

Mike Hasaballa, M.A.Sc, P.Eng.
Mike is a lead engineer and project manager in HH Angus’ Industrial/Energy team. His work focuses on the design of efficient high-performance heating and cooling systems, as well as low carbon energy systems and energy master planning. mike.hassaballa@hhangus.com

Francisco Contreras, M.A.Sc, P.Eng., LEED, AP BD+C, BEMP
Francisco is a manager and energy analyst in HH Angus’ Knowledge Management team. He is very experienced in high performance green building design, building simulations, and energy assessment. francisco.contreras@hhangus.com

Heat Pumps Reducing Your Building’s Reliance on Fossil Fuels

In Part 1 (https://hhangus.com/heat-pumps-reducing-your-buildings-reliance-on-fossil-fuels/) of this 3-part series, we discussed what heat pumps are, their benefits, and the opportunities for heat pumps to help move the world toward the transition to low carbon, as well as how engineers and owners evaluate their performance. In this installment, we examine the financial implications of using heat pump technology.

Utilizing electric heat pumps to heat buildings has long been a challenging choice for building owners. Fossil fuel heating has been the most economically viable option in many locations around the world due to lower capital and fuel costs; for example, in Canada, the cost of natural gas can be multiple times cheaper than electricity, based on location. This makes utilizing electricity for heating using heat pumps difficult from an economic perspective, even if heat pumps provide a coefficient of performance of 2 or more compared to a natural gas boiler having an efficiency of 85%.

In evaluating the true cost of heat pump heating, many building owners may not account for periods where the building requires simultaneous heating and cooling in shoulder seasons (i.e. spring and fall). In these periods, owners can pay for both heating and cooling of the building at the same time. In such cases, a heat pump could eliminate the need for fossil fuel heating and provide simultaneous heating and cooling to the building. However, it is not easy for building owners and operators to fairly evaluate the cost advantages a heat pump can provide in the shoulder seasons. A well-built building energy model can help quantify this economic advantage.

From an operations perspective, when implemented effectively, heat pumps can eliminate the need for the capital and operational costs of fossil fuel heaters, such as natural gas boilers, as well as streamline the equipment maintenance process.

Utility Costs: A Critical Factor for Owners

Utility costs can be a critical factor in the technology choice for owners in a typical building that requires heating and cooling. In Ontario (Canada) as an example, many buildings use natural gas for heating in winter and electricity for cooling in summer. It is important to highlight that these utility markets are significantly different in both cost structure and absolute costs for unit of energy. For natural gas, the utility cost is based on the type of contract with the natural gas supplier. The costs are usually determined beforehand and do not change based on time of the day. Therefore, large building owners have some level of certainty in the utility costs for heating.

However, for electricity, the costs can change based on time of use as well as consumption for residential users8. Unfortunately, for large electricity consumers (like commercial and industrial businesses) the cost structure becomes more complex. In Ontario for example, the electricity system operator (IESO) offers attractive rates if large customers can reduce their demand on the provincial electricity system during the five (5) peak hours of the year. Customers are divided into two classes that pay for electricity using different cost structures. The mechanism is called Global Adjustment (GA), where large customers can opt in to Class A rate structure and can reduce their annual electricity bill by 40 to 50% if the electrical demand (as viewed by Ontario’s grid) can be fully curtailed during these peak five hours. The other class structure (Class B) pays for electrical costs based on electricity consumption9. These costs are in addition to applicable transmission, distribution, and demand charges.

The above-mentioned market dynamics and cost structure create a financial arbitrage opportunity for all utility customers. This can happen in different ways that vary from energy storage to electricity generation behind the meter. It is worth noting that the electricity rate structure can change from one province or state to another. For utility cost calculations using heat pumps, it is strongly recommended to consult with an engineer to analyze the available opportunities, as well as the feasibility of heat pump heating applications, especially in markets that have complex electricity cost structures.

It is noteworthy that carbon reduction from electrification of heating systems will also depend on the building location and how electricity is generated in the area where the building is located. In Canada, for example, using a heat pump for building heating in Quebec can result in lower GHG emissions than in Alberta, due to differences in the GHG intensity of electricity generation between the two provinces.

Utility Costs: A Critical Factor for Owners

Since 2018, a Carbon Tax has been levied in Canada by the Federal Government, with the objective of putting a price on pollution, specifically carbon emissions. The price on carbon increased by $10 per tonne, reaching $50 per tonne of CO2 in 202210. This trend will continue, and yearly increases will get steeper after 2022 at $15 per tonne per year. By 2030, the carbon tax is expected to reach $170 per tonne of CO211 (see Figure 3). This is one of the strategies put forward by the Federal Government to help Canada meet its climate change commitments.

This is not unprecedented: as of 2021, countries such as Norway, Finland, Switzerland, and Sweden have also levied a carbon tax of $69, $73, $101, and $137 per tonne of CO2 respectively12. This tax has a direct impact on most of the energy we consume, including the energy consumed directly or indirectly by buildings and central heating and cooling plants (i.e., electricity and natural gas).

Buildings and energy systems that are designed today will be operational for many years to come; consequently, it is important to understand the impact that the carbon tax will have on utilities costs. Additionally, in countries like Canada, the impact will vary from province to province, even under the same carbon tax pricing structure, because each province has a distinct carbon footprint for their electricity grid and natural gas distribution. See Figure 4.

Figure 4. Reference provincial emission factors for electricity and natural gas13

In Ontario, for instance, based on the projected electricity grid emissions intensity and considering natural gas emissions intensity, the potential increase due to the proposed carbon tax structure is estimated as shown in Figure 5. This estimate assumes that the carbon tax associated with the utility emissions is directly passed down to clients; these estimates do not include commodity cost fluctuations.

Figure 5. Estimated increase in utility price due to Carbon Tax

Based on these assumptions, the electricity rate could increase from approximately $0.140/kWh in 2021 to $0.153/kWh by 2030, which represents a 9.3% increase due to the carbon tax. The natural gas rate could fluctuate from approximately $0.227/m3 in 2021 to $0.486/m3, which represents a 114.1% increase due to the carbon tax. These results assume an electricity rate of $0.140/kWh for 2021 (not including demand charges), electricity grid emissions intensity as per IESO’s Conservation Framework Mid-term Review - Appendix B.6 Climate Change14, a natural gas rate of $0.227/m3 for 2021, a natural gas carbon intensity of 1,888 gCO2/m3, and an annual escalation rate of 1% for both utilities.

CO2 Emissions Cost: The Break-Even Point

Historically, the use of fossil fuels has been the most cost-effective way of providing comfort heating for buildings; however, as previously mentioned, one of the objectives of the carbon tax is to put a price on pollution and make low carbon heating sources a more cost-effective solution. As the carbon tax escalates, the cost per unit of heating using fossil fuels will increase at a faster rate than the cost per unit of heating using a low carbon energy source, and an operational break-even point will be reached.

The operational break-even point between natural gas and electricity as an energy source for comfort heating will depend on a number of variables, such as carbon intensity of the electricity grid, carbon tax structure, and efficiency of heating technologies. Some heating technologies include Air Source Heat Pumps (ASHP), Air Source Variable Refrigerant Flow (ASVRF), Water Source Heat Pumps (WSHP), and Water Source Variable Refrigerant Flow (WSVRF). Understanding that the break-even point will depend on all of these variables. Figure 6 shows the estimated break-even point for a heat pump heating project in Ontario, using the same utility cost structure presented in Figure 5. This assumes a fixed seasonal COP for various heat pumps and a 1% annual improvement in available heat pump COP.

Figure 6. Heat Pumps Break-even Point, *ASHP Based on Toronto Weather

Figure 6 shows that the operational break-even point could potentially be achieved between 2023 and 2030, depending on the seasonal efficiency of the referenced natural gas heating system and the COP of the electrical heating system being proposed. Consequently, electrification should be strongly considered for replacement of existing heating systems or for new buildings, as it can become operationally more cost effective well within the life of the mechanical systems installed today.

For example, if an existing natural gas heating system with a seasonal heating efficiency of 70% is being replaced, the break-even point could be achieved by 2023 if the seasonal efficiency of the electrical heating system being proposed is at approximately 3.83, and by 2027 if the seasonal efficiency of the electrical heating system being proposed is at approximately 2.96 (which could potentially be achieved with a Cold Climate Air Source Heat Pump). On the other hand, given the low COP of electric resistance heating, cost parity is not achieved in the foreseeable future unless carbon tax escalates aggressively to more than $1,220 per tonne of CO2.

Coming up:

Part 3 of our examination of the benefits of heat pump technology wraps up with a discussion of refrigerant options and additional considerations impacting a building owner or operator’s decision to implement heat pumps, along with a summary of key take-aways.

For more information about heat pump technology or to speak with one of our energy specialists, contact us at lowcarbon@hhangus.com

Mike Hasaballa, M.A.Sc, P.Eng.
Mike is a lead engineer and project manager in HH Angus’ Industrial/Energy team. His work focuses on the design of efficient high-performance heating and cooling systems, as well as low carbon energy systems and energy master planning. mike.hassaballa@hhangus.com

Francisco Contreras, M.A.Sc, P.Eng., LEED, AP BD+C, BEMP
Francisco is a manager and energy analyst in HH Angus’ Knowledge Management team. He is very experienced in high performance green building design, building simulations, and energy assessment. francisco.contreras@hhangus.com

8 https://www.torontohydro.com/for-home/customer-choice
9 https://www.ieso.ca/en/Learn/Electricity-Pricing/What-is-Global-Adjustment
10 https://www.canada.ca/en/environment-climate-change/news/2016/10/canadian-approach-pricing-carbon-pollution.html
11 https://www.canada.ca/en/environment-climate-change/services/climate-change/pricing-pollution-how-it-will-work/carbon-pollution-pricing-federal-benchmark-information/federal-benchmark-2023-2030.html
12 https://carbonpricingdashboard.worldbank.org/map_data
13 Zero Carbon Building Design Standard Version 2 – Canada Green Building Council (CaGBC)
14 http://www.ieso.ca/en/Sector-Participants/Engagement-Initiatives/Engagements/Completed/Conservation-Framework-Mid-term-Review

Part One: Heat Pump Technology and Why We Need it

Building owners who are heating and cooling with fossil fuel energy sources are increasingly looking for solutions to reduce their buildings reliance on these fuels. This particularly applies to people-oriented buildings, such as commercial, institutional, and condo/multifamily residential buildings. Heat pump technology has come a long away in recent years; today, heat pumps are highly efficient, operate on electricity and can operate effectively in colder climates. While electricity is expensive, careful analysis reveals a heat pump solution can be more cost-effective than using natural gas. Heat pumps are also more efficient, have lower operating costs and will help owners looking to achieve net zero and significantly reduce their portfolio’s CO2 emissions. Heat pumps can also save on water use if using ground source heat pumps – more on this below.

Climate change is one of the most important challenges of our time. Buildings account for 39% of energy-related CO2 emissions on an annual basis globally1 and building operations (heating, cooling, lighting) account for 28% of emissions annually2. Lowering carbon emissions from buildings is an important element in fighting climate change. In the near future, heating buildings with fossil fuels will increasingly cease to be an option as the world shifts to low carbon. We believe that heat pumps, compared to conventional heating and cooling systems, are more efficient and, when combined with low-carbon electricity sources, will play a critical role in transitioning building heating to low carbon.

Reality Check

Globally, electric heat pumps provide less than 5% of building heating today, yet they could supply more than 90% of space and water heating, with lower CO2 emissions than condensing gas boiler technology3 in electricity grids that have low emission electricity. In Canada, 80% of the energy used in residential housing is being used for space and water heating, and this produces approximately 98%. of residential buildings’ GHG emissions4. In a broader scope, more than half of all buildings in Canada are heated by fossil fuel energy sources5 and only 2.5% of buildings use heat pump technology6.

Into the Future

Looking into the future of heat pumps in buildings, the United Nations (UN) developed seventeen Sustainable Development Goals (SDG) which were adopted by all UN member states in 2015. According to recent models, reaching these SDG would require heat pump sales to triple by the year 2030. In addition, heat pumps have to be the dominant technology for heating buildings around the globe. In a net zero scenario, heat pumps will have to replace all natural gas boiler sales that occurred over the last 20 years7, see Figure 1. This prompted us to examine the future opportunities for heat pump technology in buildings.

Data: Net Zero by 2050 (IEA)
Figure 1: Building Heating Equipment Stock, 2020 to 2050

What is a Heat Pump

A heat pump is a mechanical machine that utilizes a refrigerant to move heat energy from one place to another. This idea is based on the reversed Carnot cycle where a vapor compression refrigeration cycle uses input work to move heat from a relatively lower temperature energy source to a relatively higher temperature energy sink. The input work can come directly from a fossil fuel-based energy source, such as a natural gas-driven heat pump. Alternatively, the input work can come from an electrically-driven heat pump where the motor is driven by electricity from an electricity grid. This electricity may or may not be carbon free.

Electric heat pumps can recover low temperature energy from an energy source, elevate its temperature, and deliver it to an energy sink using a relatively small amount of electricity. In fact, the majority of the energy delivered by a heat pump used for heating comes from the low temperature energy source and not from electricity. Building owners or design engineers who evaluate heat pumps for building heating often rely on certain performance criteria to determine the benefit they can get from heat pump heating. Performance is also important when comparing heat pump heating to other heating methods, like using steam or hot water for heating, electric space heating, or direct furnace heating. The typical criteria used to evaluate heat pump efficiency is the Coefficient of Performance (COP) of the heat pump. The COP of a heat pump is the ratio between the heat delivered by the heat pump to the input work provided to the heat pump machine. In the case of electrically-driven heat pump, the input work is in the form of electricity. Therefore, the heat pump COP can be expressed as follows:

This COP (ratio) is typically greater than 1. This gives the impression that the heat pump has an efficiency higher than 100% which makes heat pump heating look attractive in terms of performance compared to other methods of heating. However, a COP higher than 1 may look significantly better than a natural gas hot water boiler efficiency but it is not necessarily the only indicator of a heat pump performance. Another way we look at a heat pump performance which is less mainstream is through comparing the ratio between the COP of a certain heat pump to the Carnot COP of the same heat pump under the same operating temperatures. The Carnot COP is the theoretical maximum COP according to the laws of thermodynamics. This ratio between a heat pump COP and the Carnot COP is always less than 1. This comparison provides us with a metric for the deviation of the COP of a certain heat pump machine we are evaluating from the theoretical maximum possible COP for this given machine. For reference, the Carnot COP is defined as:

Where all the temperatures noted above are in degrees Kelvin. This evaluation methodology highlights the importance of the design parameters of buildings such as temperature used for heating as well as environmental conditions that affect the heat source temperatures, such as outdoor air temperature or ground temperature. This helps engineers and building owners assess not only the performance of heat pump but also the feasibility of using heat pump heating in a building based on its location and building design parameters.

The good news is heat pump technology has been making consistent progress for the past decade. The performance of the current technology makes the use of heat pumps possible for a wide variety of building heating applications. However, the heating requirements for each building will determine the type of heat pump that is most suitable for the application.

Heat Pump Options

We can group heat pumps into two types based on the source of energy going into the machine: air source or water source. An air-source heat pump (ASHP) relies on air as a source of energy, which can be advantageous for climates that have mild air temperatures; however, in colder climates, the performance of air source heat pumps can deteriorate at lower outdoor air temperatures (typically below -20°C, if the energy source is outdoor air). Air source heat pumps can be installed virtually anywhere if physical space allows for the installation. This can be advantageous if there are no energy sources available to the building. However, the maximum heating capacities of an air source heat pump can be a limiting factor when using such technology for large scale applications, such as campus and district energy heating. Water source heat pumps (WSHP) use water as the energy source; this can be an advantage when abundant energy sources are available to the building, and in cold climates. If the energy source is reliable, water source heat pumps can provide building heating with a relatively smaller equipment footprint compared with air source heat pumps. Water energy sources can originate from ground, in the case of geo-exchange, or waste water heat, as well as process heat recovery in industrial applications or data centers. The caveat is that, sometimes, these energy sources may not be available to the building at all, or only available outside the building or at a distance far from the building, which can make such systems more expensive to construct.


So far, we have discussed the importance of heat pumps in combating climate change and improving overall building performance and outlined what the technology is and how it works. Stay tuned for Part 2 of our three-part discussion of heat pump technology examining the cost implications to owners and operators, as well as the considerations, opportunities and risks present for heat pump heating and how to navigate them. For more information about heat pump technology or to speak with one of our energy specialists, contact us at lowcarbon@hhangus.com.

Mike Hasaballa, M.A.Sc, P.Eng.
Mike is a lead engineer and project manager in HH Angus’ Industrial/Energy team. His work focuses on the design of efficient high-performance heating and cooling systems, as well as low carbon energy systems and energy master planning. mike.hassaballa@hhangus.com

Francisco Contreras, M.A.Sc, P.Eng., LEED, AP BD+C, BEMP
Francisco is a manager and energy analyst in HH Angus’ Knowledge Management team. He is very experienced in high performance green building design, building simulations, and energy assessment. francisco.contreras@hhangus.com

1 https://www.worldgbc.org/sites/default/files/UNEP%20188_GABC_en%20%28web%29.pdf
2 https://architecture2030.org/why-the-building-sector/
3 https://www.iea.org/reports/heat-pumps
4 https://oee.nrcan.gc.ca/corporate/statistics/neud/dpa/showTable.cfm?type=CP&sector=res&juris=ca&rn=2&page=0
5 https://oee.nrcan.gc.ca/corporate/statistics/neud/dpa/showTable.cfm?type=CP&sector=res&juris=ca&rn=7&page=0
6 https://oee.nrcan.gc.ca/corporate/statistics/neud/dpa/showTable.fm?type=CP&sector=res&juris=ca&rn=10&page=0
7 https://www.iea.org/reports/heat-pumps