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Renewable heating & cooling

What is a heat pump?

Heat pumps are used to heat and cool buildings. They don’t create heat; instead, they work by moving heat, either into or out of a specific area. When combined with solar-generated electricity, heat pumps provide homes with a renewable option for year-round heating and cooling.

Heat pumps have been a part of daily life for more than 150 years. In fact, refrigerators and air conditioners are actually heat pumps. Air conditioners move heat from the inside of a building to the outside, and refrigerators work by extracting heat from inside and discharging it as warm air from the base of the unit.

There are two primary types of heat pumps: air source heat pumps and ground source heat pumps, which are also known as geothermal heating and cooling. Air source heat pumps extract heat from the outside air and transfer it into your house, while ground source heat pumps extract heat from the earth. Both systems can be used for efficient home heating and cooling.

Why are heat pumps better?

Heat pumps are superior to standard combustion and resistance heating and cooling technologies because they move heat rather than create it. Since moving heat uses less energy than making it, heat pumps operate more efficiently than their conventional counterparts.

For example, a standard high-efficiency gas furnace turns 90% of its fuel into heat for a house, and the remaining 10% is lost up the chimney. A heat pump furnace, on the other hand, operates at between 200% and 600% efficiency, meaning that for each unit of energy that it uses, it produces 2 - 6 (and sometimes more) units of energy (heat) for your home. Additionally, heat pumps run on electricity, meaning they can be supplied with electricity from renewable resources like solar and wind.

Is electric heat bad?

In short, no, although conventional wisdom may say otherwise. One of the main reasons for this is because people often associate electric heat with electric resistance heat, which, due to the cost of electricity, can be an expensive way to heat a home.

Also, until recently, electricity was produced almost exclusively from fossil fuels. Producing electricity in this way results in significant air pollution and CO2 emissions, which in turn, has made natural gas a better choice for home heating. With the increasing availability of renewable electricity and the increased efficiency of heat pumps, electric heat pumps are the most efficient and least carbon-intensive way to heat a home.

What if I don’t want air conditioning?

Understandable! Having lived without it for years, some people have no desire for air conditioning. If we install a heat pump heating system, however, it will almost always have cooling functionalities by the very nature of its design. The good news is that you don't have to use the A/C if you don't want to. That said, the demand for cooling systems has been increasing recently and is projected to increase even more in the future. By combining your heat pump technology system with solar, you can feel good about cooling your home with renewable energy if you choose to. Furthermore, if you decide to sell your home later on, you will already have the cooling system that most buyers desire.

How does a heat pump work when it is cold outside?

Believe it or not, even cold air contains heat! Air that is warmer than absolute zero (-459˚F) contains some amount of heat. Even in very cold weather, heat pump technology is able to extract heat from the outside air, concentrate it, and move it inside a home. Some heat pump technologies are able to operate at temperatures as low as -18°F, extracting heat from the air, concentrating it, and moving it inside a home.

During the summer, heat pumps can do the same thing, except they extract heat from inside a home and move it outdoors. This is why heat pumps are superior to standard combustion and resistance heating and cooling technologies: because they move heat rather than create it. Since moving heat is easier than making it, heat pumps operate more efficiently than their conventional counterparts.

Are heat pumps reliable?

Heat pump technology is generally very reliable. Like any home equipment, though, heat pumps can have some limitations. Many heat pump systems come with a backup electric resistance heating element because, as the outside air gets colder, heat pumps decrease in efficiency and require more energy to operate. Comparatively speaking, these resistance heating elements are not very efficient, but they are very effective and will provide extra heat if the outside temperature drops so low that heat pumps no longer work well (or, when it is so cold out that it no longer makes economic sense to have them running).

Fuel Switch’s advanced energy modeling can predict the hours a home’s heat pump will operate each year, as well as the number of hours that backup electric resistance heat will be needed, which is usually for a very short amount time.

Can a heat pump work with my home’s existing heating system?

Usually, yes! Heat pumps can be applied to many types of home heating systems. The two most common heat pumps are central heat pumps and zoned “mini-split” heat pumps. A central heat pump looks and functions just like a standard central furnace. These pumps have an air handler that connects to the existing ductwork in a house, and the heat pump is positioned outside, looking like a standard air conditioner.

Mini-split heat pumps are connected to a heat pump that also sits outside, but that provides heating and cooling via wall units in each room. A single exterior heat pump can power as many as eight wall units. These mini-split heat pump systems offer homeowners the ability to control rooms individually, heating and cooling only the rooms in use, which maximizes overall efficiency.

How does it work?

Heat pumps mechanics are complicated, combining physics, chemistry, and engineering. Check out these links for more in-depth explanations of how heat pumps work their magic:

  1. https://en.wikipedia.org/wiki/Heat_pump
  2. https://www.nrel.gov/docs/fy01osti/28037.pdf
  3. https://heatpumpingtechnologies.org
  4. https://www.energystar.gov/products/heating_cooling/ductless_heating_cooling

Are heat pumps a new technology?

Actually, no. Heat Pumps have been around for more than 150 years in different forms, although the US has been slow to adopt them, in part because natural gas is inexpensive here. With recent advancements in heat pump technology that allows them to run at much colder temperatures, as well as a social push for sustainable, renewable energy options, heat pumps have been gaining popularity in North America. Since the technology is the same as standard air conditioning, most HVAC contractors have the skills, tools, and knowledge to service these systems.


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