Climate Control Systems By the Decade: What to Know About HVAC in Homes From Different Eras

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Today’s new homes are the most energy efficient homes ever built, but they only represent a small percentage of the total homes in the country. The vast majority of American homes were built in not only a different decade, but a different century. And while older homes can be retrofitted with modern and energy efficient climate control systems, how a home is constructed has a huge impact on how energy efficient it can ultimately be.

Climate control systems are constantly evolving. Whether you’re a current or prospective homeowner, or whether you’re a new and aspiring HVAC professional, it’s important to know about the types of climate control systems in homes built in different eras. Asbestos, now considered a serious health hazard, was commonly used as an insulator for a large part of the 20th century and it still remains in some homes. Other aspects of a home’s architecture, such as how air flows through it, may not be easily changed.

If you’re looking to buy an older home, it’s not a bad idea to ask the owner for a copy of a few recent utility bills to get an idea about the home’s energy consumption. But you’ll also want to know about the quirks of their native climate control systems, so you can better mitigate their inefficiencies (or avoid them altogether).

To learn more about the climate control systems of homes built in recent decades, read on.

Climate Control in Homes Built in the 1940s

A post-war economy and the rise of the automobile led to a housing boom in the second half of the 1940s. Air conditioning was still a ways away, but home heating was a necessity for a population largely located in northern climates, and several wartime innovations in heating systems became available to the consumer during peacetime. The housing boom required more affordable heating systems; radiant heating systems became popular as a result. Asbestos cement siding and roofing were also widely used during this time.

While the 1940s saw the beginnings of some modern climate control systems, the tooling and architecture of houses built in this era do not match modern standards. Houses from the 1940s lack features considered essential today for radiant heating in homes, and almost certainly have innate inefficiencies that have been made even worse over the years.

Everything HVAC-related from the time that the house was built will need to be replaced, and likely already has been more than once—but even the replacements might now be out of date.

Air conditioning will need to be installed if it hasn’t been already. A full inspection for air leaks, asbestos, and other climate control inefficiencies is recommended. Some issues (e.g., room layout, structural problems, whether the house was built on a concrete slab or not) may not be fixable from an energy-efficiency perspective.

Climate Control in Homes Built in the 1950s

The 1950s were a boom time for the American economy, and for the housing market. Returning soldiers starting families wanted cheap, modern homes in the suburbs; builders resorted to the assembly line style of tract housing.

HVAC professionals responded by experimenting with low-cost heating systems, like ductless wall heaters. Furnace rooms were also common. But air conditioning was still not standard, and homes were built for open windows and cross-ventilation in the summer.

Energy was cheap during this period, so insulation was minimal. Many homes built in the 1950s also had jalousie windows, which are ideal for summer ventilation but do not close fully, making them a major source of energy leakage in the winter.

Today, most homeowners keep their windows closed year-round, and high energy prices mean energy efficiency is now a priority. But homes with flat gravel roofs—a popular style in the 1950s—may not have adequate space for added insulation and air conditioning ducts. Furthermore, asbestos was still a common element in houses of this era. A thorough inspection of all HVAC equipment and structural components in the house is necessary.

Climate Control in Homes Built in the 1960s

The 1960s were cool: air conditioning finally went mainstream. The heat pump also solidified its place in the average American home, though its early performance levels were debatable.

Energy was still cheap in the 1960s, and houses built in this era had minimal wall insulation and single-paned windows as a result. They also are likely to have significant air leaks.

Ducted central heating systems came into use, first with forced air distributed through rigid ducts. While this was a major improvement over wall heaters, these ducts could leak at their connections. Asbestos was still common in several structural components of houses.

Furthermore, many of the previously mentioned inefficiencies from prior decades still existed in the 1960s. A thorough inspection of all HVAC equipment and structural components in a house from this era is highly recommended.

Climate Control in Homes Built in the 1970s

Due to the Baby Boomers reaching homeowner age, nearly 20 million homes were built during the 1970s—more than any other decade in the century. Air conditioners continued their march towards ubiquity, with more than half the homes in the South built after 1970 including cooling systems. Heat pumps became a major force in the HVAC industry. Solar energy lit up several expositions across the country but remained far away from (and far too expensive for) retail use.

While energy prices rose in the 1970s, energy efficiency was still not a priority when building American homes. The R-value of wall and attic insulation in the 1970s was around half of what it is in the 21st century, and many windows were still single-pane. Many of these inefficiencies may still exist.

In the mid-1970s, heating changed from rigid ducts to flexible ducts, which improved ease of installation. But the first flexible ducts were not UV-stable, meaning that direct sunlight could cause them to degrade and fall apart. Even a small amount of sunlight, such as that which can seep through the vents of an attic, was and is enough to cause significant damage to this type of ductwork.

Note that while asbestos was banned in 1978, some houses from that time may still have popcorn ceilings or other instances of asbestos. A thorough inspection of all HVAC equipment and structural components in the house is recommended.

Climate Control in Homes Built in the 1980s

An energy crisis in the late 1970s led to a search for greater energy efficiency when building homes in the 1980s. Unfortunately, many of these early attempts led to what is known as Sick Building Syndrome (SBS), where homes built tightly to prevent the loss of climate-controlled air resulted in poor indoor air quality (IAQ). By 1984, the World Health Organization (WHO) estimated that 30 percent of new and remodeled homes and buildings had poor IAQ.

A rare but significant danger for houses built in the 1980s was a horizontal furnace developed by Consolidated Industries. These furnaces were relatively low-cost heating units that could be installed in attic spaces. Unfortunately, the ones sold by Consolidated Industries were particularly prone to starting fires. A recall has since been issued for the estimated 1.2 million horizontal furnaces at risk of fire, but some remain installed in homes built in the 1980s and remain a serious fire hazard.

On the positive side, insulation in houses built in the 1980s improved significantly. The R-value of wall and attic insulation in homes built in the 1980s was about 75 percent of the standard today. Some homes started to include double-paned windows for the first time, but homes in this era are still prone to air leaks.

Also note that even though asbestos was banned in the previous decade, some houses from the early-80s may still have instances of asbestos. A thorough inspection of all HVAC equipment and structural components in the house is recommended.

Climate Control in Homes Built in the 1990s

Though they still wouldn’t match modern standards around preventing air leakage and boosting the R-value of insulation, houses built in the 1990s took energy efficiency seriously. Air conditioners finally began to shift away from refrigerants that used environmentally-unfriendly chlorofluorocarbons (CFCs). New residential heating systems like the Pulse furnace offered a nearly 50 percent increase in efficiency over their competitors. The tankless water heater also washed onto American shores: a product of Japan, it took up little space and wasted less energy than older water heaters.

The most important event of the 1990s, HVAC-wise, was the implementation of minimum energy efficiency standards for cooling and heating equipment; air conditioners, heat pumps, and furnaces purchased after 1993 had to meet minimum efficiency levels. While those are close to modern standards, HVAC systems generally last between 15 to 20 years, meaning most houses from the 1990s have had recent, major replacements to their HVAC systems—or are overdue for such replacements. A careful inspection is recommended.

Climate Control in Homes Built in the 2000s

A booming real estate market in the early- to mid-2000s led to a large increase in house construction, which sometimes affected quality. A 2011 article in Angie’s List Magazine claimed that houses built between 1997 and 2007 have more problems than houses built during any other time period. Many of those problems are structural and have side effects on the energy efficiency of a home: air leaks, insufficient insulation, and improperly sized HVAC systems.

Still, the 2000s saw the introduction of several energy-efficient standards and green building codes in new homes, which represented a significant improvement over previous decades. Homes built after the year 2000 are on average 30 percent larger than those built before, but use roughly the same amount of energy.

But homes built in the 2000s now sit at an interesting point where the original HVAC systems are just about due for replacement. Whether they have been recently replaced or not can make a significant difference in a home’s energy efficiency (and its cost). A thorough inspection is recommended.

Climate Control in Homes Built in the 2010s

The 2010s saw some of the fewest houses built in any decade, but those that were built were built to modern energy efficiency standards. Solar power became a popular fixture. The idea of sealing a house in an air envelope came into common practice and is still used today to reduce air and energy leakage. Homes from the 2010s have better insulation and more efficient HVAC systems than their predecessors, with builders taking sustainability and energy efficiency into account from day one.

Furthermore, the 2010s saw the introduction of smart systems, which used AI and internet connectivity in climate control systems for improved efficiency. However, HVAC systems continue to evolve every year, and regular maintenance is important to achieving peak efficiency.

Matt Zbrog

Matt Zbrog is a writer and researcher from Southern California. He's been living abroad since 2016. Long spells in Eastern Europe, Southeast Asia, and Latin America have made the global mindset a core tenet of his perspective. From conceptual art in Los Angeles, to NGO work on the front lines of Eastern Ukraine, to counterculture protests in the Southern Caucasus, Matt's writing subjects are all over the map, and so is he.

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