Smart, cool and recycled: 5 ways tomorrow’s buildings could be easier on the planet
Story by Yvaine Ye; illustrations by Mariah Scallan
April 14, 2026—In 2025, U.S. greenhouse gas emissions in two years, driven largely by increased fuel use for heating buildings, according to a recent report.
Commercial and residential structures are a major part of the climate equation, accounting for about a third of greenhouse gas emissions in the United States and worldwide.
In addition to powering and heating them, constructing them also takes a heavy toll. A study early this year showed that emissions from construction alone could push global warming above 2°C (3.6°F), a goal countries agreed to in the Paris Agreement to prevent the worst outcomes of climate change.
“Buildings are especially important to ourcleanenergy transition, because they consume about 75% of US electricity,” said Chuck Kutscher, a research affiliate with the Renewable and Sustainable Energy Institute(RASEI) at CU 91Ҹ.
“In Coloradowe're making excellent progress in transitioning our electric grid from coal and naturalgas to solar and wind power, and we are a national leader in adopting electric cars,” Kutscher said. “But most of our buildings are still heated with natural gas,which is primarily methane and emits pollutants.Addressing climate change will require reducing the environmental impact of construction andtransitioning to all-electric heating and cooling systems using today’s high-performance heat pumps.”
Here are five ideas CU 91Ҹ researchers are developing to reduce the climate footprint of buildings.
Turning wasted heat into a neighborhood resource
As the demand for artificial intelligence increases, technology companies are racing to build more data centers. These facilities not only consume enormous amounts of electricity, they also generate lots of waste heat.
Modern data centers use water to cool the computer processors down. Gregor Henze, professor in the Department of Civil, Environmental and Architectural Engineering, wants to reuse that heat instead.
Gregor Henze
“Data centers are basically massive toasters,” said Henze, also a RASEI fellow. “At the same time, buildings nearby might need heating. Why don’t we move the rejected heat to where it’s needed in the city?”
He envisions using underground water pipes to carry unwanted heat from data centers to nearby offices and apartments. These buildings could then extract heat from the water using heat pumps, devices that generate hot or cold air using electricity. The cooled water would eventually return to the data centers, forming a continuous loop.
Henze and his graduate student, Anneliese Fensch, simulated such a network in a neighborhood in Chicago. Using a custom designed simulation program, they modeled a community that had three apartment buildings with more than 200 units and two hospitals surrounding a small data center.
They found that in the city’s cold climate, the waste heat from one data center could supply more than enough heat for all these buildings.
In many cases, the researchers say, the challenge isn’t a lack of heat, but having far more than a neighborhood needs.
“Data centers are developed almost everywhere,” Henze said. “Part of our vision is that these facilities could actually provide a community service.”
Better window, better temperatures
Anyone who has walked into a sun-drenched office on a summer afternoon knows how quickly the windows can turn a room into a toasty greenhouse.
As average global air temperature increases, so does the use of air-conditioning. Cooling already represents around , and one recent study estimates that air conditioning-related emissions alone could boost the global-mean temperature by mid-century.
Mike McGehee, professor in the Department of Chemical and Biological engineering and a RASEI fellow, has designed a new type of window with adjustable tint that can block sunlight and keep rooms from overheating.
Mike McGehee
“While windows provide natural light, they also allow heat from the sun to enter the rooms,” said McGehee. “But even the best blinds are not very efficient in keeping the heat out.”
His technology, known as a dynamic window, embeds transparent electrodes between windowpanes. Under a small electrical current, a thin metal layer forms on the electrodes, darkening the window and blocking light. Reversing the voltage dissolves the layer and restores the window to its clear state.
When connected to a smart control system, the windows can respond dynamically to weather conditions. A window might remain clear on a cold morning to allow more heat inside, then gradually tint during the afternoon to prevent overheating.
McGehee and his team estimate that dynamic windows could reduce the energy costs associated with heating, cooling and lighting of buildings by 20% and save $44 billion a year.
“The windows can help stabilize the grid by reducing the surge in demand from air conditioning on summer afternoons,” McGehee said. “And in places without adequate access to air conditioning, these windows could protect people from extreme heat.”
McGehee and his former student, Tyler Hernandez, are working to commercialize the product through their spinoff company, .
Smart control for the grid
The power grid requires a near perfect balance between supply and demand. As utility companies race to incorporate more renewable energy from sources like solar and wind, that balancing act becomes more complex. Unlike burning fossil fuels, most renewable energy generation varies with environmental factors, because the sun isn’t always shining, and the wind isn’t always blowing.
There is also often a mismatch between when renewable energy is produced and when people use electricity, said Kyri Baker, associate professor in the Department of Civil, Environmental and Architectural Engineering and fellow at RASEI.
Kyri Baker
For example, many people run dishwashers and charge electric vehicles after work, when the sun is setting. During sunny afternoons, when solar production peaks, electricity demand at homes is often lower.
When supply and demand don’t align, utility companies may have to intentionally reduce the amount of renewable power they take on or rely on fossil fuels to fill the gap.
Baker said AI could help solve the problem. She has been designing AI-powered smart control systems that automatically shift when buildings use electricity.
For example, homes could automaticallystart pre-cooling earlier in the day when solar power is abundant and electricity is cheaper, then coast through the evening when demand spikes.
The same system could also charge electric vehicles when excess renewable energy is available.
While some homes already use smart thermostats, there needs to be a coordinated system on the utility level, so the utility companies could send signals to rotate who’s pre-cooling, or who’s charging their cars to avoid overloading the grid.
“We don’t want to be thinking about when we run our dishwasher to overlap with when it's windy. So ideally, we want to build systems to make this happen automatically,” Baker said. “If we change when and how people use energy in buildings, we can have a big impact on the broader power grid.”
Sustainable concrete
Concrete is the most widely used construction material in the world, but it comes with a steep climate cost.
Cement is the main ingredient in concrete, and it acts like a glue that holds other ingredients like water and sand together. Making cement typically requires heating raw materials, such as limestone, to extremely high temperatures, a process that releases a large amount of CO2. Today, the cement industry is responsible for 8% of global carbon emissions.
Seeking a sustainable alternative,Mija Hubler, associate professor in the Department of Civil, Environmental and Architectural Engineering, and her team, including CU 91Ҹ professors Wil Srubar, Sherri Cook and the late Jeffery Cameron, have turned to cyanobacteria for help.
Mija Hubler
These microbes use sunlight, seawater and CO2 to produce a hard, mineral shell that functions like a natural cement.
Unlike traditional cement, this biomaterial doesn’t require high heat. In addition, instead of emitting carbon, it captures and stores it during the processes.
, a CU startup founded in 2021, is commercializing the research. The company recently supplied materials for the concrete used in building part of the foundation of the Limelight Hotel 91Ҹ on the CU 91Ҹ campus. The company estimated that by mixing 40% of the bio-cement into existing commercial cement mix could offset 100% of carbon emissions in cement.
“We've been making concrete the same way for such a long time that we will run out of resources,” Hubler said. “The bio-based approach provides an alternative that’s better for our planet. We can further drive down the carbon footprint by producing the material locally.”
Hubler’s team is also exploring biological solutions for repairing concrete cracks. Instead of demolishing and rebuilding damaged structures, they hope to use a sticky cellulose-like material produced by bacteria to keep the cracks together like a tape.
“Cement is the most used construction material,” said Hubler. “Any advances we could take to improve it will have a large environmental benefit.”
Designing buildings for reuse instead of demolition
When a building reaches the end of its useful life, the typical response is to tear it down.
In the U.S. alone, demolition generates tons of construction and demolition debris annually, much of which ends up in landfills. These landfills are large emitters of methane, a highly potent greenhouse gas. Demolition also generates large amounts of greenhouse gases from the use of heavy machinery.
Azza Kamal, associate teaching professor in the Department of Environmental Design, is pushing for another approach: deconstruction. Instead of a total demolition, deconstruction involves taking down buildings piece by piece so their materials can be reused.
Azza Kamal
“Over 95% of the building materials, from the floors to the foundation and the beams, can be reused,” Kamal said. She has worked with the City of San Antonio, Texas and the City of Gainesville, Florida on preservation and deconstruction policies.
91Ҹers sometimes describe the deconstruction process as an “urban forestry” for building materials, where resources are harvested, stored and reused locally.
Currently, demolition remains far more common, because deconstruction is more expensive, takes more time and requires skilled worker. With the United States facing a shortage of 4 to 8 million homes, many cities, including Denver, are simply demolishing older properties to make way for higher density housing. Toria Lindenmuth, a former graduate student of Kamal’s, calculated that between 2014 and 2024, Denver issued a total of 5,743 demolition permits,but rarely any for deconstruction.
Urban forestry can also preserve unique architectural elements, like historic windows, doors and façades, that would otherwise be lost.
With policy support, cities like 91Ҹ, Portland and San Antonio are beginning to encourage deconstruction.
In 2023, the City of 91Ҹ completed its very first large deconstruction project at the former 91Ҹ Community Hospital. Even for a highly specialized building like a hospital, the project salvaged more than 93% of the building materials, keeping some 30 million pounds of material out of the landfill.
“These technological advances reduce air pollution and climate change emissions in both construction and operation, support a clean and stable electric grid, and reduce building sector waste,” Kutscher said. “In this way, we are moving toward a future where buildings are no longer part of the climate change problem, but rather are a key part of the solution.”