When did air source heat pumps come out?

Today, most U.S. homes have heating and/or air-conditioning systems. Depending on your region and climate, you may have both or just one, but chances are your home gets some conditioning at least part of the year.

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Not long ago, things were very different! Despite being found in 87 percent of households today, air conditioning has only been common in American homes since the late 1960s. The next time your parents or grandparents gripe about your home being too chilly when they visit, cut them some slack — they likely grew up without the luxury of home cooling.

Heating systems are a different story. There’s documented evidence of early humans using campfires for warmth almost one million years ago. As dwellings have evolved, so have the go-to methods of heating. We’ve moved from campfires to fireplaces to fossil-fuel-burning furnaces to traditional heat pumps to the energy-efficient, all-climate heat pumps of today, able to provide heating and air conditioning all year long.

So, what’s the history of the modern heat pump?

Heat Pumps: The Origin Story

To understand how we’ve reached this innovative, energy-saving technology in our homes today, let’s look at the earliest heat pumps.

The very first heat pump system is credited to Austrian scientist Peter von Rittinger, who pioneered the technology in the 1850s. His heat pump used the same basic concept as today’s heat pumps: heat absorbed from air, water or the ground is transferred indoors to heat a space, and heat absorbed from indoor air is transferred outdoors to provide air conditioning. This early technology was used in salt mines — we know, a bit of a stretch from home heating — but stay with us.

In 1928, von Rittinger’s heat pump was first used for space heating in Geneva, Switzerland via a water-source system. As the pioneers in energy technology, the Swiss get credit for being the first to produce heat pumps in mass, with several companies jumping on the bandwagon. The original heat pump system installed in Zurich’s city hall in 1937 was used until 2001 — talk about some long-lasting technology!

By 1945, heat pumps were becoming more widespread. An American inventor, Robert C. Webber, experimented with the technology and created the first functioning ground-source heat pump system. They started getting attention as an option for American homes in the 1950s and 60s and gained ground when the 1970s oil crisis spotlighted the benefits of using electricity over fossil fuels.

Efficiency Joins the Party

Conventional heat pumps run at full capacity and power regardless of environmental conditions and typically overshoot the set point or desired temperature. This lack of precision causes conventional heat pumps to waste energy by cycling on and off as the indoor temperature drifts above and below the set point.

Heat pumps could get by with this kind of performance in the early 1990s, when the U.S. Department of Energy (DoE) set minimums for HVAC products’ seasonal energy efficiency ratio (SEER) and heating seasonal performance factor (HSPF) at 10 and just under 7, respectively. But as American homeowners began to grow increasingly energy-conscious in recent decades, and the DoE continuously raised efficiency standards, demand grew for more efficient heat pump technology.

Fortunately, the solution had already been in the works in Japan, where a combination of population density and increased energy costs (Japan had been hit especially hard by the 1973 oil crisis) had motivated engineers to design more energy-efficient buildings, appliances and systems decades ago. Japanese engineers developed the first inverter-driven compressors. Heat pumps with inverter-driven compressors save energy by running continuously and ramping capacity up and down as needed. Thus, the variable-capacity heat pump was born!

A New Generation of Heat Pumps

By adjusting capacity based on real-time comfort requirements, variable-capacity systems maintain set points consistently while only using minimal electricity. After decades of successful adoption in Japan and gradual expansion overseas, Mitsubishi Electric brought variable-capacity heat pumps to the U.S. in 2001.

This introduction revolutionized the American heating and air-conditioning industry. Still today, variable-capacity systems continue to gain attention as we navigate an increasingly energy-conscious world.

The variable-capacity heat pump technology available today is a testament to how far heat pumps have come since their humble beginnings. Homeowners enjoy superior comfort; environment-friendly, all-electric operation; reliable performance in all climates and reduced energy consumption by up to 40 percent compared to conventional heat pump systems.

If only von Rittinger could see his creation now!

For more information on our all-electric heat pump products and technologies, visit MitsubishiComfort.com.
 

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Like phones, televisions, and even cars, today’s split heat pump systems are very different from the originals installed in homes decades ago. Over time, their indoor comfort effectiveness and energy-efficient heat transfer properties have allowed heat pumps to grow in popularity - gaining approval from homeowners across the country.

Evolution of the Heat Pump

Every generation is shaped by world events and major cultural, political, and economic influences. These events have also impacted the evolution and popularity of the split system heat pump. Let’s look at the generational breakdown of the evolution of the split system, air-source heat pump:

• Baby Boomer (born approximately between 1946 and 1964)

  :

  In the 1950 and 60s, heat pumps were becoming an electric heating option for the residential marketplace. By the late 1960s, the average Baby Boomer was in their 20s and purchasing their first home. Suburban neighborhoods continued to expand across the country. Although air conditioners were available in some of these new homes, heat pumps were not a conventional heat source.

  According to the 1960 US Census, only 1.8% of homes used electricity as a source of heat.1 Nearly 81% used some form of ‘fuel’ to keep their home warm in the cold months of the year.1 By the 1970 US Census, 7.7% of households used electricity as a source of heat.1

• Generation X (born approximately between 1965 and 1980)

  : By the 1970s, an oil crisis was in full swing with many Generation Xers witnessing the full brunt of its impacts. As a result of the crisis, the heat pump became a more popular choice for heating and cooling homes because they used electricity instead of fuel.2 The decreased supply of fuel increased the cost, which may have played a significant factor in this growth. By 1980, 18.4% of homes used electricity as a source of heat, more than doubling the rate of the previous decade.3
  
  Before 1980, the heat pump may have been merely an available alternative to fuel. Heat pumps, which have energy-efficient heat transfer properties, had a Seasonal Energy Efficiency Rating (SEER) of 6 or less and a Heating Seasonal Performance Factor (HSPF) of below 5. Energy-efficiency and conservation didn’t seem to be the primary objective. By 1992, the energy conservation movement was in full swing, and Generation X’s push for more energy-efficient products was evident. As a result, the U.S. Department of Energy (DOE) raised the minimum energy-efficiency standards of heat pumps to 10 SEER/ 6.8 HSPF.

• Millennial (born approximately between 1981 and 1994)

  : By the early 2000s, the average Millennial was a teenager, and energy efficiency was a mainstream concept. During this time, nearly 67% of the population were used fuels as a heat source and 30.3% used electricity 4 Yet, energy conservation and minimizing environmental impacts continued to be an actionable 

  priority. In 2006, the DOE raised the minimum required SEER/HSPF standards for split system heat pumps from 10 SEER/6.8 HSPF to 13 SEER/7.7 HSPF nationwide.

  By 2016, Millennials became the largest sector in the U.S. labor force, and the DOE once again raised the minimum SEER/HSPF requirement for split system heat pumps.5

• Generation Z (1995 to early 2000s)

  : Born during a time of technological innovation, Generation Z is accustomed to accessing information at their fingertips. In 2011, smart thermostats, such as the Google Nest, started populating the marketplace and indoor comfort could be controlled from mobile devices. As a result, some segments of Generation Z will never live in an environment with any other form of indoor temperature control.
  
  

  By 2015, the majority of Generation Z was enrolled in school and nearly 12.1 million households used electric heat pumps for indoor comfort.6

  By 2020 the first waves of Generation Z were absorbed into the workforce and first-time home ownership was a reality for a few in their mid-20s. Meanwhile, heating and cooling equipment manufacturers continued to embrace technology-based, energy-efficiency advancements such as inverter technology. Heat pumps installations were increasing and shipments of air source heat pumps continued to escalate at a record pace.7

• Generation Alpha (early 2010s to 2020s)

  : 

  This young generation is growing up in a fully digital world where it's commonplace for technology to set expectations. By 2023, the heating and cooling industry continues to evolve and heat pump adoption numbers continue to rise.

  Based on the data, advancements in heat pump technology are resulting in greater adoption across the U.S. as a heating and cooling equipment source. From 2018 to 2022, according to Air Conditioning, Heating, and Refrigeration Institute (AHRI) data, there was nearly a 68% jump in shipments of heat pumps from U.S. manufacturers.8

NOTE: AHRI defines a shipment as when a unit transfers ownership from a manufacturer.8

As communities across the country are engaging in decarbonization and sustainability efforts, generations of citizens are embracing heat pumps and electrification. The Inflation Reduction Act of 2022 included a 10-year, historic plan to encourage customers to invest in energy-saving retrofits and replace inefficient HVAC systems. This legislation includes significant rebates and increased tax incentives for homeowners to replace fossil-fuel systems with eligible, high-efficiency ENERGY STAR® products. As part of this policy, qualified homeowners may be eligible for up to a $2,000 tax credit for eligible heat pumps. In the coming decade, Generation Alpha will certainly be influenced by the current decarbonization policies and the push for heat pump adoption.

What will indoor comfort expectations be like for a generation where technology sets expectations?

There may come a time when homeowners ‘expect’ their heat pump to directly communicate status updates either to them, or their HVAC professional. Will their notion of “normal” extend to home heating and cooling equipment? Only time will tell!

More Heat Pump Options

Historically, air source heat pumps were only installed for homes in milder climates. However, in recent years, technology and engineering has allowed heat pumps to create a cozy, comfortable, electric heating alternative for homes in colder regions. Today’s cold climate heat pumps systems are now being installed from Alaska to Florida.9

Unlike the heat pump systems of the past, some of today’s models are equipped with inverter technology, like the Amana® brand S Series Heat Pump. Heat pumps with inverter technology are designed to control and modulate the electrical current running into the compressor’s motor, the heart of the indoor comfort system. This energy-saving technology allows the heat pump to adjust how much energy is needed to maintain indoor comfort. If looking to reduce Co2 emissions by investing in a heat pump, consider one that includes the benefits of inverter technology. 

Additional advancements, including design and engineering evolutions, smart controls, and other mechanics that simplify installation have also impacted the indoor comfort and energy costs associated with residential heat pumps.

"Smart" Home Comfort

Numerous smart thermostats now offer a wide range of control features and connectivity with virtual assistants and smartphones, making it easier to align your heat pump operation with your lifestyle. As technology continues to become more integrated into heating and cooling equipment, the future of heat pumps will most likely evolve.

Imagine a technician contacting you because they received a diagnosis notification from your heat pump. This technician could potentially arrive at your home for a repair or proactive maintenance before you ever experience an uncomfortable temperature in your home. Future generations may never know what it is like to walk into a hot or cold home on a sweltering or frigid day! Isn’t that a comforting thought!

1, 3, 4 United States Census Bureau. (2011, October 31). Historical Census of Housing Tables. Retrieved from Census of Housing: https://www.census.gov/data/tables/time-series/dec/coh-fuels.html.
2 Cormany, Charles. The Perfect Solution, and Why it is Not Working. 19 January 2017. http://www.efficiencyfirstca.org/news/2017/01/19/perfect-solution-and-why-it-not-working. 30 July 2017.
5 Pew Research Center. The Generations Defined. 8 May 2015. https://www.pewresearch.org/fact-tank/2018/04/11/millennials-largest-generation-us-labor-force/ 15 Feb 2023.
6. U.S. Energy Information Administration, U.S. households’ heating equipment choices are diverse and vary by climate region, April 6, 2017. https://www.eia.gov/todayinenergy/detail.php?id=30672
7. AHRI, Monthly Shipments Feb 12, 2021 https://www.ahrinet.org/sites/default/files/2023-02/Dec2020StatisticalRelease_4.pdf
8. International Energy Agency, Heat Pumps, September 2022 https://www.iea.org/reports/heat-pumps
9. Vanessa Stevens, Colin Craven, Robbin Garber-Slaght. Air Source Heat Pumps in Southeast Alaska. Fairbanks: Cold Climate Housing Research Center, 2013. http://www.cchrc.org/sites/default/files/docs/ASHP_final_0.pdf

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