Heat Pumps for Space Heating and Cooling
Heat Pumps for Water Heating and Cooling
Introduction to Heat Pumps
What are Heat Pumps
How Heating With a Cold Climate Heat Pump is Different From a Conventional Furnace
Benefits of Heat Pumps
How Do Heat Pumps Work?
Many of us rarely think about the systems that bring comfort to our homes. Warm air in winter, cool air in summer, hot water available whenever we want it . Yet for most homes, these comforts come with a heavy price for climate. Homes contribute roughly ⅓ to our personal carbon footprint while buildings in general are responsible for nearly 40% of global greenhouse gas emissions (1). In most cases, it is the fossil fuels that we burn to heat our spaces and water that is the biggest problem.
Fortunately, there is a solution. Modern heat pumps can heat our water and condition our living spaces many times more efficiently than conventional systems such as furnaces and baseboard heaters. In geographies such as Ontario, where the electricity supply is largely decarbonized, heat pumps that run on electricity are one of the best technologies available to cut emissions from our homes and other buildings. Governments everywhere are increasingly looking to heat pumps as a means of addressing emissions from buildings: you are likely to be hearing far more about heat pumps in the coming years. We invite you to learn more about heat pumps and how they can be great choices for your home and for our climate.
What Are Heat Pumps
Heat pumps are mechanical systems that use electricity to move heat from one place to another. They are very efficient, using far less energy to heat a space than it would take to generate the same heat by burning a fuel. And they can move heat in either direction, to cool a space in summer and to heat it in the winter. ... Heat pumps have also been around for a long time: the first heat pump was built in 1857 and Geneva’s City Hall in Switzerland installed a heat pump in 1928 that is still in use today (2). The technology keeps getting better: homes that use modern heat pump systems are very comfortable in all seasons even in Waterloo Region’s climate, and they can also go a long way toward reducing our carbon footprints.
As our community, our province, the nation and the world transition off of fossil fuels to prevent catastrophic climate change, heat pumps will play an increasingly important role in our homes. ... Indeed, the Intergovernmental Panel on Climate Change (IPCC), the International Energy Agency (IEA) and other energy experts have been recommending a switch to heat pumps for quite some time. Today, most government climate action plans promote heat pump adoptions as a means of cutting greenhouse gas emissions from buildings.
How Heating With a Cold Climate Heat Pump is Different From a Conventional Furnace
A home heated with a cold climate heat pump will be very comfortable year round. Achieving home comfort efficiently is different however, than with a conventional furnace. Conventional furnaces release hotter air than a heat pump but for a much shorter time. A heat pump will therefore run for longer and release air that isn’t as hot but this means more even temperatures throughout the day which will feel more comfortable. A home heated with a heat pump will use energy more efficiently when the thermostat is set at a constant temperature and setbacks at night or during unoccupied periods are minimized
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Energy efficiency is improved and longevity of the heat pumps compressor may be greater when all air vents are kept open and free of obstructions.
On cold and damp days, frost can build up on the outside unit of a heat pump, reducing its ability to absorb heat from the outside air. When this occurs, most heat pumps will briefly run in reverse, drawing heat from the home to defrost the outside unit. Backup resistance heat may be used during this time to minimize the effect any discomfort from having cool air blow out of the ductwork. Defrost cycles are triggered by sensors that detect the effect of frost buildup or by a timer: the first system is more energy efficient.
As our community, our province, the nation and the world transition off of fossil fuels to prevent catastrophic climate change, heat pumps will play an increasingly important role in our homes. ... Indeed, the Intergovernmental Panel on Climate Change (IPCC), the International Energy Agency (IEA) and other energy experts have been recommending a switch to heat pumps for quite some time. Today, most government climate action plans promote heat pump adoptions as a means of cutting greenhouse gas emissions from buildings.
Benefits of Heat Pumps
- Can provide all of your home’s heating and cooling, or hot water needs
- Are more energy efficient because they move heat rather than generating heat
- Can replace a furnace and an air conditioning system or a conventional water heater
- Can make your home comfortable year round
- Use electricity, which can be sourced from renewables
- Generate fewer greenhouse gas emissions compared to natural gas furnaces when operating, especially if powered by clean electricity
- Do not generate any harmful carbon monoxide in the home when operating
- Can operate very quietly
How Do Heat Pumps Work?
Heat pumps use the mechanical refrigeration cycle to move heat from one place to another. Just as your fridge moves heat from a cool place to a warmer place (inside the fridge to the kitchen), so too does your heat pump. A heat pump is even better than a fridge though because it is reversible, moving heat into the home in winter and out of the home in summer.
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In simple terms, the refrigeration cycle works as follows (see Figure 1). A refrigerant gas at low pressure and temperature absorbs heat through an evaporator in the location where we want to gather heat from (for example from outside in winter, from inside in summer). A compressor then squeezes the gas, which raises the pressure and the temperature of the gas. The heat that was absorbed is sent through a condenser to the place where we want to direct the heat (for example, inside in winter and outside in summer). The refrigerant is then allowed to expand at the expansion valve which lowers the pressure and temperature and the cycle starts again. The process is reversible so that heat always travels in the desired direction: toward the inside in winter and toward the outside in summer.
Heat pumps are not only used for space heating and cooling, they can also be used to heat water for domestic use or for boilers. Heat pumps of all kinds are very energy efficient because they can move several units of heat energy with every unit of electrical energy. The net result is the transfer of heat from one location to another using very little added energy.
- Heather McDiarmid - climate change consultant who owns an ASHP
- Andrew Schiedel - data geek who owns an ASHP
- Ryan Fobel - a data geek who has looked into HPWH
- Joe Tanel - HVAC specialist who installed his own HPWH
- John Kokko - HVAC specialist
- Rebecca McIntosh - Realtor who knows what people are asking about HPs and owns an ASHP
- Eric Praetzel - engineer and data geek who owns an ASHP
The authors of this website verified the data and information used in this guide to the best of their abilities but do not guarantee its accuracy, especially as the technology continues to evolve. The authors have no affiliation with any manufacturers or installers of heat pumps, nor have they received sponsorship from any source. The guide is intended for information purposes only, and homeowners are urged to consult with several experienced heat pump installers to get information that is current and specific to their home.
(1) IEA. (2019). Global Status Report for Buildings and Construction 2019, IEA, Paris https://www.iea.org/reports/global-status-report-for-buildings-and-construction-2019
(2) https://saveonenergy.ca/For-Your-Home/Advice-and-Tips/ASHP-Guide