HVAC Design and Efficiency
Learn more at www.oerproject.comHVAC Design and EfficiencyBy Molly Sinnott, research by Beverly BrownExplore how we can provide comfortable indoor temperatures for people everywhere and reduce emissions from heating and cooling.
2HVAC Design and EfficiencyBy Molly Sinnott, research by Beverly BrownThe state of HVAC todayI live in Seattle, where we like to joke about “June-uary” because the month of June tends to be so chilly and wet it feels like we’re back in January. Seattle is known for mild summers, which meant air conditioning was unusual in the city. But that’s all been changing as extreme heat has pushed summer temperatures into the triple digits. Recent high temperatures caused illness and even deaths as Seattleites scrambled to install air conditioning in their homes. And they’re not alone— as temperatures get more extreme, global demand for HVAC systems to maintain livable temperatures is increasing dramatically.In California, officials urged residents to use caution and conserve energy during a 2022 heat wave that caused temperatures to rise above 112° F. © Getty Images.HVAC stands for heating, ventilation, and air conditioning. This term refers to the way we keep our indoor environments comfortable—not too hot in the summer, and not too cold in the winter. Anyone who’s spent a stuffy August day in a high school classroom knows just how important it is to have good HVAC. And temperature control is no longer merely a convenient luxury. It’s increasingly necessary for health and survival in many communities around the world. HVAC is also an equity issue, since the communities with the fewest resources often have the least access to this technology. And in many parts of our economy, services like food transportation and resources like office buildings, hospitals, and the large complexes that house computer servers rely on heating and cooling systems to function. But the HVAC systems that keep our homes, buildings, and vehicles comfortable are responsible for a lot of greenhouse gas emissions. Heating and cooling systems are responsible for 7% of annual global emissions. To keep a cool head about this hot topic, let’s explore the most promising innovations and how you can help get them into wider use.
3HVAC Design and EfficiencyBy Molly Sinnott, research by Beverly BrownLeading innovations for heating and cooling Efficient air conditioning If you live in the average U.S. home, your air conditioner (AC) is the biggest consumer of electricity you own—more than your lights, refrigerator, and computer combined. Today there are 1.5 billion AC units in use around the world, most of them in the United States and other wealthy countries. Lower-income countries, however, are the ones that tend to experience the most extreme heat. This means that as incomes rise and global populations increase, so will demand for air conditioners. Experts predict that by 2050 there’ll be as many as 6 billion AC units in use. To put that in perspective, that’s about ten new air conditioners every second for the next thirty years.The International Energy Agency (IEA) predicts that by 2050, there will be up to 6 billion AC units in use around the world. By IEA, CC BY 4.0.The answer isn’t to use les air conditioning. People everywhere deserve to be able to keep their homes at reasonable temperatures. Rather, we need AC units that are more efficient, that use less electricity to cool us. This efficiency matters for two reasons. First, most electricity comes from burning fossils fuels, so more electricity to run an AC unit means more carbon emissions. Second, on extremely hot days, when more people are running air conditioners, inefficient units put more strain on the electrical grid. This can lead to blackouts when the power grid collapses under intense demand. The good news? We have the technology we need—right now! The most efficient air conditioners on the market today are up to three times more efficient than the average unit in use.
4HVAC Design and EfficiencyBy Molly Sinnott, research by Beverly BrownWhat’s keeping these efficient AC units from being more widely installed? Adoption remains low because newer and more efficient units tend to be more expensive than standard models. More efficient units, however, often save money in the long run due to their lower electricity costs. But many consumers don’t take these savings into account and look only at the price tag when deciding what type of unit to buy. Some just can’t afford to pay the up-front price difference. They include people in lower-income countries and communities, but also those on fixed incomes, like many elders. Better cooling gases High electricity use isn’t the only problem with many AC units. There are also the refrigerants that do the work of cooling. Refrigerant refers to the chemical mixture that cycles through an air conditioner, changing from a liquid to a gas as it absorbs and releases heat. Refrigerants often leak out of an AC system. That’s a problem because traditional refrigerants are incredibly powerful greenhouse gases—thousands of times more potent than carbon dioxide, in fact. To deal with this, some companies are developing alternatives to traditional cooling gas. Many are already using a compound that’s roughly two-thirds less harmful than the standard refrigerant. This alternative is also easily recyclable, making it more likely it won’t be released into the atmosphere when an AC unit is retired. But it’s not perfect. So some researchers are looking at ways to use naturalrefrigerants. These cooling gases are called “natural” because they don’t have to be synthesized in a lab. They include substances like ammonia and propane. Natural refrigerants are promising because they have near zero global-warming potential. Still other companies are exploring innovations like magnetic refrigeration. This technology uses positive and negative magnetic fields to generate heat or cold without emissions. The exposed ceiling of this grocery store shows the many pipes pumping refrigerants through the building to keep the products cold. Grocery stores have high demand for refrigeration, but they leak about 25% of their refrigerants annually. New supermarkets are promising places to make the switch to natural refrigerants. © Getty Images.
5HVAC Design and EfficiencyBy Molly Sinnott, research by Beverly BrownWhile promising alternatives to traditional cooling gases exist, there are obstacles to overcome before they’re widely used. So although less potent refrigerants can and should replace traditional ones, even these alternatives have significant warming potential and won’t get us to zero. Natural refrigerants can be dangerous: Ammonia is toxic, while propane is highly flammable. Plus, they require a completely different systems of pipes and storage, so they can’t work with pre-existing structures. Innovative technologies like magnetic refrigeration are still in development and need more research before they are ready to use commercially. Improved heating systemsDon’t be misled by our discussion of keeping cool on hot days. Cold weather isn’t going anywhere. In fact, climate change means that extreme weather—not just hot weather but also periods of intense cold—will be even more common in coming years. Traditionally, buildings use furnaces, boilers, or water heaters to heat air and water. But most of these systems run on fossil fuels like natural gas, propane, and oil. Together, these heating systems are responsible for 30% of emissions from buildings.However, these traditional systems are not our only option for staying warm when temperatures drop. Heat pumpsare systems that can both heat andcool our homes by moving heat from one place to another. An air source heat pump works by pulling heat directly from the air. In the summer, the refrigerants in the coils of a heat pump pull heat from inside your house then releases it outside, leaving the inside of your house cooler. In the winter, it works in the opposite direction, pulling heat from the outside to warm the air indoors. Geothermal heat pumps are another style of heat pump that operate by pulling heat from the ground rather than the air. Even if the weather is scorching hot or freezing cold, the ground just a few feet below the surface of the earth remains at a relatively constant temperature. Geothermal heat pumps take advantage of this fact by using underground pipes to bring in ground heat in the winter and cool air in the summer. Technicians install an air source heat pump outside a home. © Getty Images.
6HVAC Design and EfficiencyBy Molly Sinnott, research by Beverly BrownWhen the electricity needed to operate heat pumps comes from renewable sources, these systems are net-zero emitters. Plus, heat pumps often save people money—the cost of running an electric heat pump is usually less than that of running an AC unit and furnace or boiler. Heat pumps sound pretty great, right? They’re cheaper and more efficient than the alternatives. So why are they in only about 10% of U.S. homes? Well, average furnaces and boilers have a lifespan of up to 20 years. It’s not reasonable to expect many homeowners will replace functioning equipment before it’s necessary. Some consumers also aren’t aware of the cost-saving potential of heat pumps when they’re shopping for new heating systems. And heat pumps require space outside a house, which makes them more challenging to install in dense urban areas. Action opportunities and careersThe exciting thing about HVAC design and efficiency is that we have most of the technology we need available right now. What can you do to help get these innovations in use in more homes and buildings?To start, we need policy to encourage adoption. For example, some countries in Europe have successfully lowered emissions by offering subsidies to consumers to encourage them to buy heat pumps. Similarly, some communities in the United States have banned the installation of fossil fuel-burning heating systems in new city building projects. Governments can also set stricter performance standards so that all AC units on the market meet a minimum efficiency standard. Some of these policies might be right for the area where you live, and you could encourage local policymakers to support them. We also need to increase awareness to ensure people are making informed decisions when buying heating and cooling systems. One way to do that is to make sure consumers are aware of the long-term cost saving potential of more efficient devices. What’s more, there may already be policies in place that can help people in your community save money when buying new heating and cooling systems. For example, the Inflation Reduction Act of 2022 offers tax incentives for people to install heat pumps in their homes. You can help educate your community about their options to reduce HVAC emissions at a lower cost. Or you might choose to follow a career to help bring heat and cooling emissions to zero. We’re going to need a lot of trained technicians to install efficient HVAC systems in homes and buildings. Scientists like chemical engineers are needed to continue improving refrigerants for air conditioning units. And we’ll need city officials, architects, and builders to work together to ensure that new construction is developed with the most efficient heating and cooling technology. How will you help?Experts like these engineers are needed to install and maintain efficient HVAC systems. © Getty Images.
7HVAC Design and EfficiencyBy Molly Sinnott, research by Beverly BrownMolly Sinnot and Beverly BrownMolly Sinnott is a member of the Climate Project editorial team. She was previously a classroom reading and writing teacher, specializing in supporting students in executive-function skills development. She focuses on building approachable and inclusive content for a diverse range of students. Beverly Brown is a member of the Climate Project team living and working in Washington DC as a college administrator and adjunct lab instructor. She is a graduate student studying mechanical engineering and has a bachelor’s degree in astrophysics and government. She uses her interdisciplinary background to create informative and accessible science writing for broad audiences. Credit: “HVAC Design and Efficiency”, By Molly Sinnott, research by Beverly Brown / OER Project, https://www.oerproject.com/Image credits This work is licensed under CC BY 4.0 except for the following: Cover image: Thermostat, close-up. © Jeffrey Hamilton / Stockbyte / Getty Images.In California, officials urged residents to use caution and conserve energy during a 2022 heat wave that caused temperatures to rise above 112° F. © PATRICK T. FALLON / AFP / Getty Images.The International Energy Agency (IEA) predicts that by 2050, there will be up to 6 billion AC units in use around the world. By IEA, CC BY 4.0. https://www.iea.org/fuels-and-technologies/coolingThe exposed ceiling of this grocery store shows the many pipes pumping refrigerants through the building to keep the products cold. Grocery stores have high demand for refrigeration, but they leak about 25% of their refrigerants annually. New supermarkets are promising places to make the switch to natural refrigerants. © Victoria Jones / PA Images / Getty Images.Technicians install an air source heat pump outside a home. © Andrew Aitchison / In Pictures / Getty Images.Experts like these engineers are needed to install and maintain efficient HVAC systems. © sturti / E+ / Getty Images.OER Project aims to empower teachers by offering free and fully supported history courses for middle- and high-school students. Your account is the key to accessing our standards-aligned courses that are designed with built-in supports like leveled readings, audio recordings of texts, video transcripts, and more. Offerings include a variety of materials, from full-year, standards-based courses to shorter course extensions, all of which build upon foundational historical thinking skills in preparation for AP, college, and beyond. To learn more about The OER Project, visit www.oerproject.com