Buildings

A really efficient methane gas-burning furnace can be 95% efficient.  That means that it turns 95% of the energy stored in the methane into usable heat.  An electric heat pump can be 400% efficient.  How is that possible?  (What does it even mean?)  If you ask a physicist, and you catch them with their guard down, they’ll tell you: it’s basically magic.

A heat pump doesn’t turn the energy in electricity into heat energy, in the way that a toaster does.  Instead, it uses electricity to move (pump) heat around, from one place to another.  It works the same way a refrigerator does.  Coils full of fluid pull heat out of the cold air inside your fridge, and release it into the warm air in your kitchen, making the kitchen air even warmer.  In the summer, that’s exactly what an air-source heat pump does, too: it works as an air-conditioner, pulling heat out of the air in your home, and pumping it into the hot outdoor air.  But a heat-pump can also run in the opposite direction: in winter, it can pull heat out of the air outdoors (even if that air is already really cold) and release it into your home to warm the indoor air.  It can be 400% efficient, because one unit of electrical energy is enough to move four units of heat energy from one place to another. 

Ground-source heat pump systems are sometimes called “geothermal heating” because they pull heat out of the earth. This name can be confusing though, because “geothermal energy” also refers to a very different technology for producing electricity from the earth’s heat, as we discuss in our page on cleaning up electricity. To avoid confusion, we’ll save the term “geothermal” for geothermal electricity production. A ground-source heat pump works in the same way that an air-source heat pump does, but instead of coils full of fluid transferring heat to or from the air, coils full of fluid transfer heat to or from the ground, which stays a pretty consistent 55° F once you get a few feet underground. Less energy is needed to pump heat into 55° earth than into hot summer air; and less energy is needed to pump heat out of 55° earth than out of the cold winter air; so ground-source heat pumps are even more efficient than air-source ones.  But they usually cost more up-front to install, because you have to dig deep holes in the ground for the fluid to loop through.

⇒ To learn how one smart start-up is working to make ground-source heat pumps affordable, listen to this podcast interview with Kathy Hunan, founder of Dandelion Energy.

Both air-source and ground-source heat pumps can heat and cool commercial buildings and multi-family apartments as well as single-family homes.  Because they don’t burn anything, there’s no risk of carbon monoxide poisoning or explosions.  And because they continuously adjust the intensity they run at to keep a room at the desired temperature (rather than just switching between on and off like a conventional furnace), they’re much more comfortable.   Living in a home with a heat pump is like driving an EV: it’s not just environmentally healthier; it’s a better experience          .

⇒ Check out this memo describing five heat-pump powered buildings in New York City, including a 44 story mixed-use tower.

In addition to heating the air inside our homes, heat pump technology can also be used to heat the water that comes out of our taps.  A heat pump hot water heater can be 3.5 times more efficient than a traditional electric hot water heat (one that works like a toaster, with an electric heating element), and a crazy seven times more efficient than a gas-burning hot water heater.

One more advantage of heat pumps: because they run on electricity, they can be paired with rooftop solar, so that a home can provide most of its own energy over the course of a year, and with a home battery (or an electric pickup truck), so that your heat pump can run through a power outage.

Over the last few years, a series of ever-more-alarming studies have shown that gas cookstoves pose serious dangers to health.  When gas is burned during cooking, it releases nitrous oxides (NOx), carbon monoxide, and formaldehyde, all of which cause respiratory illnesses like asthma and COPD.  Gas stoves create indoor air pollution above legal limits for safe outdoor air; and children living in homes with gas stoves have a 42 percent higher risk of asthma symptoms.  Gas stoves leak gas even when they’re turned off, as do the pipes that deliver gas to your home and inside your home; and that uncombusted gas contains 21 different “air toxics” – including several, like Benzene, linked to cancer.   

We don’t need new technology to avoid all this: electric stoves have been around forever.  But no one loves cooking on a traditional electric stove.  Their heating elements take a long time to get hot and a long time to cool down, so they don’t have the sort of instant, precise control that cooks need.  No wonder many cooks prefer gas.  

Induction stoves solve this problem.  They run on electricity, but they don’t work like a traditional electric stove.  There’s no heating element.  Instead, an electric current runs through an electromagnetic coil underneath the surface of the cooktop, generating a magnetic field. This makes the electrons in your metal pan vibrate, heating the pan. You can set the pan to the precise temperature you want, and you can change it instantly.  A pot full of water boils in two minutes.  Like heat pumps and EVs, induction stoves are just better, even if you’re not thinking about your own health or the planet’s.

If electrified buildings are better, healthier, and nicer to live in and they save money, why aren’t we electrifying them at the rapid pace we need in order to avoid climate disaster?  

Part of the problem is that the world has a lot of buildings.  Just in the US, there are 111 million of them, 90% of which are single-family homes – and each one is a little bit different.  That means that millions of people need to decide to electrify, find a way to pay the up-front costs, and find a contractor who is willing and able to figure out the right set-up for their particular building.

Nate “The House Whisperer” Adams is an HVAC contractor working to speed electrification in the US.  He argues that one part of the problem is that 20 years ago, heat pumps worked poorly in cold climates, and contractors who installed them had to make emergency service calls to angry customers in the middle of winter.  So, contractors in cold places stopped installing them – and many still will not, even though the technology in heat pumps has improved radically in recent years, so that they now work well even in extremely cold winters.  Contractors matter, because homeowners and building owners replace furnaces and water heaters when they break.  When it’s cold and they don’t have heat, people don’t have time or inclination to research the best technology.  Instead, they turn to a contractor, who installs what they’re already comfortable with and have ready to hand.   Nate is trying to address this by building networks to educate homeowners and contractors alike. 

⇒ Listen to this great Energy Gang podcast with Nate “The House Whisperer”

An obvious way to push through or over these obstacles is with public policies.  

• Governments (local, state, or national) can offer financial incentives to electrify existing buildings, to reduce the upfront costs for building owners.   
• As Saul Griffith argues in chapter 12 of Electrify, governments can back low-interest loans to make it affordable to electrify existing buildings – just as the US federal government did for electric appliances in the 1930s, and still does for some home mortgages.
• The US federal government can pass a bill like the HEATR Act, which offers manufacturers of central air conditioners a financial incentive to spend the extra $400 per unit that is required to make the air-conditioners they sell into two-way heat pumps, capable of heating and cooling.  That way, the 6 million Americans who replace their central air conditioners each year would be getting a heat pump at the same time. 
• Cities and states can alter building codes to encourage or require electrification whenever a furnace or cooktop is replaced.  (Right now, many building codes make electrification more difficult and expensive than it needs to be.)   
• Cities and states can prohibit new buildings being built with gas hookups. The city of Berkeley, California passed a law prohibiting gas hookups in new construction in 2019, and at least 77 other US cities have already followed them.  Several states are now considering similar gas bans state-wide.  These bans don’t affect existing buildings, but they do respect the principle that when you’re in a hole, the first step is to stop digging.   It’s cheaper and better to design a building to be all-electric from the start than to retrofit it later.  And experience building all-electric homes helps contractors to become comfortable with heat pumps.

All of these policies would help homeowners and building owners save money.  Why aren’t we enacting them everywhere?  There’s a simple answer: they threaten the profits of gas companies and utilities, and so these companies have been fighting policies like this, hard.  At the local level, they fund law suits against local gas bans that have been passed, and they create front groups with names like “Coloradans for Energy Access,” complete with fake Facebook profiles, to fight against new ones.  They charge customers who switch from gas to electric a $1400 “exit fee.”  They pay actors to show up at City Council meetings pretending to be ordinary citizens.  They secretly take over local newspapers, publishing stories that support their interests.  And, just since 2020, they have used their money and political power to get legislatures in 20 states to pass state-level “pre-emption” bills that prohibit cities in those states from enacting gas bans.     

⇒ Listen to this Carbon Copy podcast about Florida’s law preventing its cities from enacting gas bans

⇒ Read this jaw-dropping article on some of the dirty tricks that utilities employ to keep gas flowing

This means that the challenge of electrifying building is not just technological, social, and financial.  It is a political fight – one that needs to be fought at every level of government, from national to very local.  (For more, see the section on Climate Policy under Climate Careers.)

One hopeful development could help to defuse this fight, by turning some of the strongest opponents of electrification into allies.   In February 2022, Massachusetts regulators approved a pilot program allowing gas distribution utilities to create six “GeoMicroDistricts.”  The utilities, which already have equipment and a workforce skilled in laying pipes beneath city streets, will create networksof underground pipes carrying fluid for ground-source heat pumps throughout a neighborhood.  This network will bring hot (or in the summer, cold) fluid into homes and businesses; and those buildings will be able to install heat pumps to draw heat (or cooling) from that fluid. Connecting many buildings together in this way is more efficient and less expensive than installing separate ground source heat-pumps beneath individual buildings.  If this project succeeds, gas utilities will have a future in a decarbonized world: they will be able to transition from delivering piped gas to delivering piped zero-carbon heat.  The idea is already catching on.  In July, 2022 New York State passed a law creating a pilot program like the one in Massachusetts.

⇒ Listen to this great Volts podcast interview with the team behind the “GeoMicroDistricts” idea.

⇒ Read “District Heating,” in in Drawdown, p. 99 to learn about similar projects already in use in Europe.

“Renewable Natural Gas” (RNG, also called biomethane or biogas) is methane produced by bacteria digesting organic waste material – whether in landfills, farms, livestock operations, or sewage treatment plants – which would escape into the atmosphere if it were not captured and put to use.  When it is captured, it can be low-carbon-equivalent on net, because the warming power of the greenhouse gasses released in the course of capturing, compressing, transporting and combusting it may be balanced out by the warming power of the methane that would have gone straight into the atmosphere if it were not captured.  It is a “drop-in” replacement for fossil methane: it can be transported in the same pipes, then used in existing equipment in homes, businesses, and industry.  For these reasons, gas utilities promote it heavily as a path to decarbonization.  They propose to begin by mixing small a percentage of biomethane into their supply, and then increasing the percentage over time. 

Because methane is such a potent greenhouse gas, capturing and using biomethane where it exists, before it escapes into the atmosphere, is a good idea.  And there are some “hard-to-abate” industrial processes where captured biomethane can usefully be put to work.  But there is not nearly enough biomethane to replace most of the fossil gas that we use now. 

That’s actually a good thing.  Fugitive biomethane leaking from pipes is still a super-potent greenhouse gas, just like fossil methane.  Biomethane still produces pollutants like NO_x when it’s burned, just like fossil methane.  And low income people and communities of color still live closest to the factories and refineries that would use biomethane, and would still suffer from it disproportionately.

⇒ To learn more about the way in which fossil gas companies are pushing biomethane, even though it is not a realistic or desirable solution for most uses, read this great explainer from David Roberts.

Gas companies propose that they could distribute hydrogen, rather than fossil methane, to homes and businesses, where it could be combusted in furnaces and stoves.  Burning hydrogen does not emit carbon dioxide, and hydrogen can be produced in ways that do not emit carbon dioxide either – most notably, by using renewable electricity to electrolyze water.  However, hydrogen burns differently from methane, so existing furnaces and stoves would have to be replaced to burn pure hydrogen.  And because hydrogen molecules are much smaller than methane molecules, pure hydrogen would both damage and escape from most existing gas pipes.  So, gas companies propose to start by mixing hydrogen with the methane that they already deliver in small quantities, thus partially decarbonizing the energy they provide. 

This is another case of gas utilities grasping for a way to stay in business.  No more than 5% hydrogen can be mixed with methane in existing pipes without damaging them.  Because hydrogen is less dense than methane, this would supply less than 2% of delivered energy content.  And producing hydrogen without carbon emissions and then combusting it are both inefficient processes. (See our discussion in the page on transportation.)  These inefficiencies can be worth accepting in some industrial and transportation uses that cannot easily be electrified.  But this make no sense at all as a way of heating buildings.  Delivering one unit of heat to a home via “green” hydrogen would require five to six times more renewable electricity than delivering it with a heat pump.  This would in turn require five to six times more generating capacity, five to six times more resources to produce that capacity, and five to six times more land to site it on.

These are important climate solutions!  It’s much easier for a heat pump to keep a well-insulated building warm or cool than a leaky one.  And new buildings built to standards like Passive House can be so efficient that they hardly need any HVAC at all.   

⇒ Check out:

• “Net Zero Buildings,”in Drawdown, pp. 84–85
• “Green Roofs,” in Drawdown, pp. 90-91
• “Smart Glass,” in Drawdown, pp. 96-97
• “Smart Thermostats,” in Drawdown, p. 98
• “Insulation,” in Drawdown, p. 101
• “Retrofitting,” in Drawdown, pp. 102-103
• “Building Automation,” in Drawdown, p. 106
• “Living Buildings,” in Drawdown, pp. 188-189
• Amanda Sturgeon, “Buildings Designed for Life” in All We Can Save, pp. 166-169

An efficient building heated by fossil-fuels is better than an inefficient building heated by fossil fuels.  But as Saul Griffith says, “we can’t efficiency our way to zero.”   So it’s important that efficiency is used as a complement to building electrification, not a substitute for it.

We’re glad you asked!

1. Because the challenge of electrifying buildings is, in part, a political challenge, it has political solutions!  State-level policy is key, but individual cities can do a lot.  As we describe on the Climate Careers Overview page, the cities of Ithaca, New York and Menlo Park, California have voted to electrify every building they have in the next few years, and they’re working with a smart company, BlocPower, to get the job done.  Even if a city isn’t ready to be so ambitious, there’s a lot it can do just by strengthening its local building code.  Every city that does this helps to accelerate the snowball rolling down, and makes it easier for the next city to do the same. Organize a campaign to electrify your city – or run for local office, and push for these policies from the inside!
2. Many businesses are finding clever, innovative ways to make it simpler and cheaper for homeowners and building owners to electrify.  Individual contractors are building local businesses around electrification.  Startups like Goodleap provide low-cost financing specifically designed for sustainability improvements to homes, and a seamless marketplace to purchase and finance those improvements.  Sealed will insulate and electrify your home with no upfront cost, and with monthly payments coming only from your energy savings, so that you never have to pay more than you did before the retrofit.  And there are many more.  Help build a business, or start one, that removes obstacles to electrification.
3. If you own a home (or have family members who do), electrify it!  Climate change is a systems problem, and most of our individual consumer choices have little impact on it.  But as Griffith points out in chapter 9 of Electrify, choices regarding our homes and our vehicles are different. These are our personal infrastructure, which we use every day.  Together, they account for more than 40% of Americans’ emissions.  (If we include offices and company cars, the number goes to 60%.)  So, this is one place where individual choices really can make a meaningful difference. Everyone’s decisions matter, because the only way to decarbonize buildings is one building at a time.  And our decisions are contagious: when people visit friends’ electrified home, and realize it’s more comfortable and more economical, they want one themselves.
4. Push your workplace or school to electrify.  It will save money, make your workplace more comfortable, and help us preserve a livable planet.  Many colleges are making the necessary investments because of pressure from students, faculty and other employees, and alumuni.