Feature left bracketright bracket Winter 2023

Sustainability of the Built Environment

Researchers seek solutions for a source of 40 percent of carbon emissions worldwide—human-made infrastructure.

Colorful illustration showing how WPI researchers are working on the sustainability of the built environment

Roads threatened by coastal flooding. Homes battered by hurricanes. Air quality tested by heat waves. Communities faced with costly choices. All are linked to climate change, the long-term and accelerating shift in global temperatures and weather patterns associated with greenhouse gas emissions from human activity.

No single source is responsible for those emissions, and no simple solution for the problem exists. Yet one often-overlooked area—one that accounts for an estimated 40 percent of carbon emissions worldwide—is known as the built environment: roads, bridges, buildings, and other types of human-made infrastructure.

That’s why, in the laboratories at WPI, researchers are working on sustainable construction materials and building designs, computational models, and other advances that could not only reduce emissions related to construction and operation of the built environment, but help communities plan for and adapt to disasters and economic impacts that have been intensified by a changing climate.

“It will be critical to do many different things to reduce the impact that buildings, materials, and construction have on global emissions,” says Carrick Eggleston, professor and head of the Department of Civil, Environmental, and Architectural Engineering (CEAE). “We will need to develop new materials and retrofit older structures, all while assisting those who are least able to make the changes that are needed.”

Inspiration From Nature

When it comes to the hunt for new materials, Steven Van Dessel thinks nature might be a good place to look for inspiration.

“The field of bio-inspired materials is promising and wide open for exploration,” says Van Dessel, who is a CEAE associate professor and director of WPI’s architectural engineering program. “The goal is to discover cost-effective solutions that can easily be implemented not just in new buildings, but in existing buildings, because that is where there’s potential to have the greatest impact.”

The goal is to discover cost-effective solutions that can easily be implemented not just in new buildings, but in existing buildings, because that is where there’s potential to have the greatest impact.

Steven Van Dessel

He is working on new concepts for building envelope design—solutions that would allow a building to regulate its own temperature by using solar energy and smart materials that store and release heat.

With colleagues, including CEAE Associate Professor Mingjiang Tao and Clark University chemistry Professor Sergio Granados-Focil, Van Dessel is conducting basic research into smart polymers that could be integrated into construction coatings, foams, or other materials.

The researchers are developing new approaches for thermal energy storage that use reversible chemical reactions between sorbents and sorbates to store and release energy, much like a battery. Other work focuses on phase-change materials that, when used in coatings for windows or roofing, changes from clear or opaque under different temperatures to admit or block solar energy. A third area of research involves investigating changes to the thermal conductivity of materials to make them more or less insulating and adapt to environmental conditions and climate.

The biological inspiration comes from plants’ abilities to adapt to changes in the environment. Solid materials that change from opaque to transparent, depending on temperatures, could absorb and release heat much like how layers of a plant leaf function. Phase-change foams that the researchers studied resemble some of the cross-sectional features of a plant leaf.

“We’re trying to combine a number of different technologies into a smart system to create buildings that are comfortable for people and use zero energy from the power grid,” Van Dessel says. “It will likely require materials with different functions, especially for buildings in different climates.”

Turning a Problem into a Solution

Concrete may not be the flashiest building material, but it’s cheap, strong, and widely available. It’s also a problem for the planet.

“Concrete production and transport accounts for 9 percent of global CO2 emissions,” says Nima Rahbar, CEAE associate professor. “That’s not sustainable. We need to find alternatives to concrete that are strong, durable, and non-polluting. In fact, it will be important to develop carbon-negative materials that will absorb CO2 because we need to reduce the effect of climate change.”

Toward that goal, Rahbar and Suzanne Scarlata, professor in the Department of Chemistry and Biochemistry, have developed an enzymatic construction material (ECM) that is made of sand, gelatin, calcium, and trace amounts of a naturally occurring enzyme, carbonic anhydrase, in a process that consumes CO2 from the air. The researchers described their material in the journal Matter and says the ECM could also “heal” itself through exposure to CO2 and a calcium source, which causes a chemical reaction capable of depositing new material into damaged areas.

“The process uses carbonic anhydrase to capture carbon dioxide,” Scarlata says. “CO2 is everywhere, and we can change the form of CO2 into something that’s not causing climate change.”

The researchers have also added iron oxide nanoparticles to ECM and treated the material with incandescent light or a laser. Rahbar and Scarlata reported in Cell Reports Physical Science that the method could make it possible to manufacture ECM without oven heating and enable rapid repairs to the self-healing ECM.

Their work has led to the launch of a startup company, Enzymatic Inc., that is commercializing the technology. The researchers also recently were awarded $692,386 from the National Science Foundation to improve and develop new functions for their ECM.

Illustration depicting self-healing concrete research

For Rahbar, working on ECM represents a chance to positively impact both his field of civil engineering and, ultimately, the world. It is a path he took at the encouragement of WPI Interim President Wole Soboyejo, who was Rahbar’s PhD advisor when both were at Princeton University.

“I was working on the mechanics and physics of materials, and he said to me, ‘Why don’t you do something for the field of civil engineering?’” Rahbar says. “This is the way I can do that.”

Making Buildings Comfortable

Shichao Liu studies indoor environments such as homes, offices, schools, and cars for an important reason: That’s where humans spend most of their time.

“Most people stay indoors for about 90 percent of each day,” says Liu, a CEAE assistant professor who is affiliated with the Department of Fire Protection Engineering. “To understand human well-being during climate change, we have to look at how occupants of buildings are affected by extreme weather and disasters, such as heat and wildfires.”

In his Building Occupants Signal Synthesis (BOSS) Lab, Liu is bringing together advanced sensors and artificial intelligence to understand the impact that indoor spaces have on the comfort, health, and happiness of occupants.

Illustration depicting the impact of climate change on indoor environments

Liu and his collaborators have examined how indoor temperatures, air quality, lighting, and sound levels affected college students’ mental health and learning during the COVID-19 pandemic. The work, funded with a $199,999 grant from the National Science Foundation, showed a weak, but not negligible, link between indoor environmental factors and depression the students experienced.

He has also built a driving simulator to study how carbon dioxide levels and chemicals emitted by the human body affect driving performance. With funding from WPI’s Transformative Research and Innovation Accelerating Discovery (TRIAD) seed grant program, he has led an interdisciplinary study of how temperature, humidity, lighting, sounds, and air quality affect group decision-making.

Liu’s interest in indoor environments arose partly from his own experiences—he grew up in a home without central heating or air-conditioning. Now he sees that, in some communities, a significant percentage of residents live in low-income households that lack the resources to sustainably cool hot rooms and filter wildfire smoke from the air in their homes.

“Rather than cool entire buildings, it might be better to adapt existing systems with smart devices to create comfortable microenvironments around individuals,” Liu says. “That could include pointing cool or warm air to specific points in a room or developing origami-like structures that could surround a person and limit the amount of space that needs to be heated or cooled. Solutions for those who are most vulnerable to climate change will need to be simple and inexpensive.”

Storms, Flooding, and Roads

When Hurricane Katrina descended on New Orleans in 2005, it killed more than 1,800 people, displaced thousands more, and damaged buildings and infrastructure. Just weeks later, Hurricane Rita swept into southwestern Louisiana, causing additional destruction.

As floodwaters receded from the region, a researcher at the Louisiana Transportation Research Center in Baton Rouge became interested in a critical question: Just how safe are the roads that have been submerged in floods?

“A flooded road may look fine, but the layers below the paved surface can be weakened by flooding,” says Mingjiang Tao, now a CEAE associate professor at WPI. “It’s like looking at a patient who appears healthy but is actually very sick.”

Tao’s research has focused primarily on making transportation infrastructure more sustainable and resilient. He has worked to develop risk assessment models that will enable federal, state, and local transportation agencies to make proactive long-term planning and informed short-term response to climate-compounded hazards.

“With climate change and more extreme weather, it’s not just coastal communities that will be impacted by hurricanes and severe storms,” Tao says. “Locations far from the coasts are experiencing flooding and disruptions to infrastructure. This is a complex problem, and there is a practical need to help communities that are vulnerable to climate change but lack the staff and resources to prepare for its effects.”

Illustrating the effect of climate change on infrastructure

And with other researchers, Tao has also investigated durable and sustainable asphalt alternatives, including recycled asphalt pavement, to reduce the amounts of new materials going into road construction. He has studied geopolymers that could be synthesized from abundant industrial byproducts like coal ash and red mud to create a greener cement than the ordinary portland cement now used in mixing concrete.

Making Decisions When Climate Changes

Two important things to know about climate change, according to Sarah Strauss, professor in the Department of Integrative and Global Studies (DIGS) in The Global School, are that it intensifies existing problems and upends zoning and construction expectations that were based on historic experiences.

“Climate change shows us that ‘natural’ disasters now are often not really natural,” says Strauss. “If we think about Florida, where marshes have been drained and paved over, rising seawater now has nowhere to drain. This raises questions about what communities are doing as they build and repair infrastructure, add housing, and think about the things that society has come to expect in the built environment.”

An anthropologist who co-directs WPI’s master of science program in Community Climate Adaptation, Strauss has studied the way that communities address climate change and has co-edited an anthropological examination of climate in the book Weather, Climate, Culture, published in 2004. Her more recent work focuses on transitions to renewable energy systems (Cultures of Energy, Power, Practice, Technologies, 2013), looking at how communities are responding to the need to reduce greenhouse gases.

It won’t always be possible for communities to do things in the future the way they did things in the past, but using our collective imagination to envision and produce a vibrant and innovative path forward is very much within our grasp.

Sarah Strauss

Climate change is a global problem, but the strategies we take to address this challenge are local and depend on the needs, histories, resources, and desires of different communities, Strauss says. Those solutions also have implications about justice and equity for the people in those communities.

As a collaborator on the TRIAD-funded study led by Liu, Strauss participated in research into how temperature, humidity, lighting, sounds, and air quality affect group decision-making. One takeaway from the research was that people will need to have conversations about whether to continue doing the things they’ve always done, the things that grow from a community’s culture but may lead to impacts in the future. That could mean not rebuilding a structure that was destroyed in a disaster, or even moving a community to a location less vulnerable to disasters.

“Building and rebuilding are not just a matter of mechanics, materials, and locations,” says Strauss. “There will be conversations about the things that were not considered when a community formed, when settlers created a certain kind of society in a place, or when people paved over marshes. There is a need for conversations about whether people can continue doing things that they have always done, or how they want to ‘build back better.’ It won’t always be possible for communities to do things in the future the way they did things in the past, but using our collective imagination to envision and produce a vibrant and innovative path forward is very much within our grasp.”

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