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    Study shows a link between obesity and what’s on local restaurant menus

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    For many years, health experts have been concerned about “food deserts,” places where residents lack good nutritional options. Now, an MIT-led study of three major global cities uses a new, granular method to examine the issue, and concludes that having fewer and less nutritional eating options nearby correlates with obesity and other health outcomes.Rather than just mapping geographic areas, the researchers examined the dietary value of millions of food items on roughly 30,000 restaurant menus and derived a more precise assessment of the connection between neighborhoods and nutrition.“We show that what is sold in a restaurant has a direct correlation to people’s health,” says MIT researcher Fabio Duarte, co-author of a newly published paper outlining the study’s results. “The food landscape matters.”The open-access paper, “Data-driven nutritional assessment of urban food landscapes: insights from Boston, London, Dubai,” was published this week in Nature: Scientific Reports.The co-authors are Michael Tufano, a PhD student at Wageningen University, in the Netherlands; Duarte, associate director of MIT’s Senseable City Lab, which uses data to study cities as dynamic systems; Martina Mazzarello, a postdoc at the Senseable City Lab; Javad Eshtiyagh, a research fellow at the Senseable City Lab; Carlo Ratti, professor of the practice and director of the Senseable City Lab; and Guido Camps, a senior researcher at Wageningen University.Scanning the menuTo conduct the study, the researchers examined menus from Boston, Dubai, and London, in the summer of 2023, compiling a database of millions of items available through popular food-delivery platforms. The team then evaluated the food items as rated by the USDA’s FoodData Central database, an information bank with 375,000 kinds of food products listed. The study deployed two main metrics, the Meal Balance Index, and the Nutrient-Rich Foods Index.The researchers examined about 222,000 menu items from over 2,000 restaurants in Boston, about 1.6 million menu items from roughly 9,000 restaurants in Dubai, and about 3.1 million menu items from about 18,000 restaurants in London. In Boston, about 71 percent of the items were in the USDA database; in Dubai and London, that figure was 42 percent and 56 percent, respectively.The team then rated the nutritional value of the items appearing on menus, and correlated the food data with health-outcome data from Boston and London. In London, they found a clear correlation between neighborhood menu offerings and obesity, or the lack thereof; with a slightly less firm correlation in Boston. Areas with food options that include a lot of dietary fibers, sometimes along with fruits and vegetables, tend to have better health data.In Dubai, the researchers did not have the same types of health data available but did observe a strong correlation between rental prices and the nutritional value of neighborhood-level food, suggesting that wealthier residents have better nourishment options.“At the item level, when we have less nutritional food, we see more cases of obsesity,” Tufano says. “It’s true that not only do we have more fast food in poor neighborhoods, but the nutritional value is not the same.”Re-mapping the food landscapeBy conducting the study in this fashion, the scholars added a layer of analysis to past studies of food deserts. While past work has broken ground by identifying neighborhoods and areas lacking good food access, this research makes a more comprehensive assessment of what people consume. The research moves toward evaluating the complex mix of food available in any given area, which can be true even of areas with more limited options.“We were not satisfied with this idea that if you only have fast food, it’s a food desert, but if you have a Whole Foods, it’s not,” Duarte says. “It’s not necessarily like that.”For the Senseable City Lab researchers, the study is a new technique further enabling them to understand city dynamics and the effects of the urban environment on health. Past lab studies have often focused on issues such as urban mobility, while extending to matters such as mobility and air pollution, among other topics.Being able to study food and health at the neighborhood level, though, is still another example of the ways that data-rich spheres of life can be studied in close detail.“When we started working on cities and data, the data resolution was so low,” Ratti says. “Today the amount of data is so immense we see this great opportunity to look at cities and see the influence of the urban environment as a big determinant of health. We see this as one of the new frontiers of our lab. It’s amazing how we can now look at this very precisely in cities.” More

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      Building resiliency

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      Several years ago, the residents of a manufactured-home neighborhood in southeast suburban Houston, not far from the Buffalo Bayou, took a major step in dealing with climate problems: They bought the land under their homes. Then they installed better drainage and developed strategies to share expertise and tools for home repairs. The result? The neighborhood made it through Hurricane Harvey in 2017 and a winter freeze in 2021 without major damage.The neighborhood is part of a U.S. movement toward the Resident Owned Community (ROC) model for manufactured home parks. Many people in manufactured homes — mobile homes — do not own the land under them. But if the residents of a manufactured-home park can form an ROC, they can take action to adapt to climate risks — and ease the threat of eviction. With an ROC, manufactured-home residents can be there to stay.That speaks to a larger issue: In cities, lower-income residents are often especially vulnerable to natural hazards, such as flooding, extreme heat, and wildfire. But efforts aimed at helping cities as a whole withstand these disasters can lead to interventions that displace already-disadvantaged residents — by turning a low-lying neighborhood into a storm buffer, for instance.“The global climate crisis has very differential effects on cities, and neighborhoods within cities,” says Lawrence Vale, a professor of urban studies at MIT and co-author of a new book on the subject, “The Equitably Resilient City,” published by the MIT Press and co-authored with Zachary B. Lamb PhD ’18, an assistant professor at the University of California at Berkeley.In the book, the scholars delve into 12 case studies from around the globe which, they believe, have it both ways: Low- and middle-income communities have driven climate progress through tangible built projects, while also keeping people from being displaced, and indeed helping them participate in local governance and neighborhood decision-making.“We can either dive into despair about climate issues, or think they’re solvable and ask what it takes to succeed in a more equitable way,” says Vale, who is the Ford Professor of Urban Design and Planning at MIT. “This book is asking how people look at problems more holistically — to show how environmental impacts are integrated with their livelihoods, with feeling they can have security from displacement, and feeling they’re not going to be displaced, with being empowered to share in the governance where they live.”As Lamb notes, “Pursuing equitable urban climate adaptation requires both changes in the physical built environment of cities and innovations in institutions and governance practices to address deep-seated causes of inequality.”Twelve projects, four elementsResearch for “The Equitably Resilient City” began with exploration of about 200 potential cases, and ultimately focused on 12 projects from around the globe, including the U.S., Brazil, Thailand, and France. Vale and Lamb, coordinating with locally-based research teams, visited these diverse sites and conducted interviews in nine languages.All 12 projects work on multiple levels at once: They are steps toward environmental progress that also help local communities in civic and economic terms. The book uses the acronym LEGS (“livelihood, environment, governance, and security”) to encapsulate this need to make equitable progress on four different fronts.“Doing one of those things well is worth recognition, and doing all of them well is exciting,” Vale says. “It’s important to understand not just what these communities did, but how they did it and whose views were involved. These 12 cases are not a random sample. The book looks for people who are partially succeeding at difficult things in difficult circumstances.”One case study is set in São Paolo, Brazil, where low-income residents of a hilly favela benefitted from new housing in the area on undeveloped land that is less prone to slides. In San Juan, Puerto Rico, residents of low-lying neighborhoods abutting a water channel formed a durable set of community groups to create a fairer solution to flooding: Although the channel needed to be re-widened, the local coalition insisted on limiting displacement, supporting local livelihoods and improving environmental conditions and public space.“There is a backlash to older practices,” Vale says, referring to the large-scale urban planning and infrastructure projects of the mid-20th century, which often ignored community input. “People saw what happened during the urban renewal era and said, ‘You’re not going to do that to us again.’”Indeed, one through-line in “The Equitably Resilient City” is that cities, like all places, can be contested political terrain. Often, solid solutions emerge when local groups organize, advocate for new solutions, and eventually gain enough traction to enact them.“Every one of our examples and cases has probably 15 or 20 years of activity behind it, as well as engagements with a much deeper history,” Vale says. “They’re all rooted in a very often troubled [political] context. And yet these are places that have made progress possible.”Think locally, adapt anywhereAnother motif of “The Equitably Resilient City” is that local progress matters greatly, for a few reasons — including the value of having communities develop projects that meet their own needs, based on their input. Vale and Lamb are interested in projects even if they are very small-scale, and devote one chapter of the book to the Paris OASIS program, which has developed a series of cleverly designed, heavily tree-dotted school playgrounds across Paris. These projects provide environmental education opportunities and help mitigate flooding and urban heat while adding CO2-harnessing greenery to the cityscape.An individual park, by itself, can only do so much, but the concept behind it can be adopted by anyone.“This book is mostly centered on local projects rather than national schemes,” Vale says. “The hope is they serve as an inspiration for people to adapt to their own situations.”After all, the urban geography and governance of places such as Paris or São Paulo will differ widely. But efforts to make improvements to public open space or to well-located inexpensive housing stock applies in cities across the world.Similarly, the authors devote a chapter to work in the Cully neighborhood in Portland, Oregon, where community leaders have instituted a raft of urban environmental improvements while creating and preserving more affordable housing. The idea in the Cully area, as in all these cases, is to make places more resistant to climate change while enhancing them as good places to live for those already there.“Climate adaptation is going to mobilize enormous public and private resources to reshape cities across the globe,” Lamb notes. “These cases suggest pathways where those resources can make cities both more resilient in the face of climate change and more equitable. In fact, these projects show how making cities more equitable can be part of making them more resilient.”Other scholars have praised the book. Eric Klinenberg, director of New York University’s Institute for Public Knowledge has called it “at once scholarly, constructive, and uplifting, a reminder that better, more just cities remain within our reach.”Vale also teaches some of the book’s concepts in his classes, finding that MIT students, wherever they are from, enjoy the idea of thinking creatively about climate resilience.“At MIT, students want to find ways of applying technical skills to urgent global challenges,” Vale says. “I do think there are many opportunities, especially at a time of climate crisis. We try to highlight some of the solutions that are out there. Give us an opportunity, and we’ll show you what a place can be.” More

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      in Environment

      MIT delegation mainstreams biodiversity conservation at the UN Biodiversity Convention, COP16

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      For the first time, MIT sent an organized engagement to the global Conference of the Parties for the Convention on Biological Diversity, which this year was held Oct. 21 to Nov. 1 in Cali, Colombia.The 10 delegates to COP16 included faculty, researchers, and students from the MIT Environmental Solutions Initiative (ESI), the Department of Electrical Engineering and Computer Science (EECS), the Computer Science and Artificial Intelligence Laboratory (CSAIL), the Department of Urban Studies and Planning (DUSP), the Institute for Data, Systems, and Society (IDSS), and the Center for Sustainability Science and Strategy.In previous years, MIT faculty had participated sporadically in the discussions. This organized engagement, led by the ESI, is significant because it brought representatives from many of the groups working on biodiversity across the Institute; showcased the breadth of MIT’s research in more than 15 events including panels, roundtables, and keynote presentations across the Blue and Green Zones of the conference (with the Blue Zone representing the primary venue for the official negotiations and discussions and the Green Zone representing public events); and created an experiential learning opportunity for students who followed specific topics in the negotiations and throughout side events.The conference also gathered attendees from governments, nongovernmental organizations, businesses, other academic institutions, and practitioners focused on stopping global biodiversity loss and advancing the 23 goals of the Kunming-Montreal Global Biodiversity Framework (KMGBF), an international agreement adopted in 2022 to guide global efforts to protect and restore biodiversity through 2030.MIT’s involvement was particularly pronounced when addressing goals related to building coalitions of sub-national governments (targets 11, 12, 14); technology and AI for biodiversity conservation (targets 20 and 21); shaping equitable markets (targets 3, 11, and 19); and informing an action plan for Afro-descendant communities (targets 3, 10, and 22).Building coalitions of sub-national governmentsThe ESI’s Natural Climate Solutions (NCS) Program was able to support two separate coalitions of Latin American cities, namely the Coalition of Cities Against Illicit Economies in the Biogeographic Chocó Region and the Colombian Amazonian Cities coalition, who successfully signed declarations to advance specific targets of the KMGBF (the aforementioned targets 11, 12, 14).This was accomplished through roundtables and discussions where team members — including Marcela Angel, research program director at the MIT ESI; Angelica Mayolo, ESI Martin Luther King Fellow 2023-25; and Silvia Duque and Hannah Leung, MIT Master’s in City Planning students — presented a set of multi-scale actions including transnational strategies, recommendations to strengthen local and regional institutions, and community-based actions to promote the conservation of the Biogeographic Chocó as an ecological corridor.“There is an urgent need to deepen the relationship between academia and local governments of cities located in biodiversity hotspots,” said Angel. “Given the scale and unique conditions of Amazonian cities, pilot research projects present an opportunity to test and generate a proof of concept. These could generate catalytic information needed to scale up climate adaptation and conservation efforts in socially and ecologically sensitive contexts.”ESI’s research also provided key inputs for the creation of the Fund for the Biogeographic Chocó Region, a multi-donor fund launched within the framework of COP16 by a coalition composed of Colombia, Ecuador, Panamá, and Costa Rica. The fund aims to support biodiversity conservation, ecosystem restoration, climate change mitigation and adaptation, and sustainable development efforts across the region.Technology and AI for biodiversity conservationData, technology, and artificial intelligence are playing an increasing role in how we understand biodiversity and ecosystem change globally. Professor Sara Beery’s research group at MIT focuses on this intersection, developing AI methods that enable species and environmental monitoring at previously unprecedented spatial, temporal, and taxonomic scales.During the International Union of Biological Diversity Science-Policy Forum, the high-level COP16 segment focused on outlining recommendations from scientific and academic community, Beery spoke on a panel alongside María Cecilia Londoño, scientific information manager of the Humboldt Institute and co-chair of the Global Biodiversity Observations Network, and Josh Tewksbury, director of the Smithsonian Tropical Research Institute, among others, about how these technological advancements will help humanity achieve our biodiversity targets. The panel emphasized that AI innovation was needed, but with emphasis on direct human-AI partnership, AI capacity building, and the need for data and AI policy to ensure equity of access and benefit from these technologies.As a direct outcome of the session, for the first time, AI was emphasized in the statement on behalf of science and academia delivered by Hernando Garcia, director of the Humboldt Institute, and David Skorton, secretary general of the Smithsonian Institute, to the high-level segment of the COP16.That statement read, “To effectively address current and future challenges, urgent action is required in equity, governance, valuation, infrastructure, decolonization and policy frameworks around biodiversity data and artificial intelligence.”Beery also organized a panel at the GEOBON pavilion in the Blue Zone on Scaling Biodiversity Monitoring with AI, which brought together global leaders from AI research, infrastructure development, capacity and community building, and policy and regulation. The panel was initiated and experts selected from the participants at the recent Aspen Global Change Institute Workshop on Overcoming Barriers to Impact in AI for Biodiversity, co-organized by Beery.Shaping equitable marketsIn a side event co-hosted by the ESI with CAF-Development Bank of Latin America, researchers from ESI’s Natural Climate Solutions Program — including Marcela Angel; Angelica Mayolo; Jimena Muzio, ESI research associate; and Martin Perez Lara, ESI research affiliate and director for Forest Climate Solutions Impact and Monitoring at World Wide Fund for Nature of the U.S. — presented results of a study titled “Voluntary Carbon Markets for Social Impact: Comprehensive Assessment of the Role of Indigenous Peoples and Local Communities (IPLC) in Carbon Forestry Projects in Colombia.” The report highlighted the structural barriers that hinder effective participation of IPLC, and proposed a conceptual framework to assess IPLC engagement in voluntary carbon markets.Communicating these findings is important because the global carbon market has experienced a credibility crisis since 2023, influenced by critical assessments in academic literature, journalism questioning the quality of mitigation results, and persistent concerns about the engagement of private actors with IPLC. Nonetheless, carbon forestry projects have expanded rapidly in Indigenous, Afro-descendant, and local communities’ territories, and there is a need to assess the relationships between private actors and IPLC and to propose pathways for equitable participation. 

      Panelists pose at the equitable markets side event at the Latin American Pavilion in the Blue Zone.

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      The research presentation and subsequent panel with representatives of the association for Carbon Project Developers in Colombia Asocarbono, Fondo Acción, and CAF further discussed recommendations for all actors in the value chain of carbon certificates — including those focused on promoting equitable benefit-sharing and safeguarding compliance, increased accountability, enhanced governance structures, strengthened institutionality, and regulatory frameworks  — necessary to create an inclusive and transparent market.Informing an action plan for Afro-descendant communitiesThe Afro-Interamerican Forum on Climate Change (AIFCC), an international network working to highlight the critical role of Afro-descendant peoples in global climate action, was also present at COP16.At the Afro Summit, Mayolo presented key recommendations prepared collectively by the members of AIFCC to the technical secretariat of the Convention on Biological Diversity (CBD). The recommendations emphasize:creating financial tools for conservation and supporting Afro-descendant land rights;including a credit guarantee fund for countries that recognize Afro-descendant collective land titling and research on their contributions to biodiversity conservation;calling for increased representation of Afro-descendant communities in international policy forums;capacity-building for local governments; andstrategies for inclusive growth in green business and energy transition.These actions aim to promote inclusive and sustainable development for Afro-descendant populations.“Attending COP16 with a large group from MIT contributing knowledge and informed perspectives at 15 separate events was a privilege and honor,” says MIT ESI Director John E. Fernández. “This demonstrates the value of the ESI as a powerful research and convening body at MIT. Science is telling us unequivocally that climate change and biodiversity loss are the two greatest challenges that we face as a species and a planet. MIT has the capacity, expertise, and passion to address not only the former, but also the latter, and the ESI is committed to facilitating the very best contributions across the institute for the critical years that are ahead of us.”A fuller overview of the conference is available via The MIT Environmental Solutions Initiative’s Primer of COP16. More

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      in Environment

      Has remote work changed how people travel in the U.S?

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      The prevalence of remote work since the start of the Covid-19 pandemic has significantly changed urban transportation patterns in the U.S., according to new study led by MIT researchers.

      The research finds significant variation between the effects of remote work on vehicle miles driven and on mass-transit ridership across the U.S.

      “A 1 percent decrease in onsite workers leads to a roughly 1 percent reduction in [automobile] vehicle miles driven, but a 2.3 percent reduction in mass transit ridership,” says Yunhan Zheng SM ’21, PhD ’24, an MIT postdoc who is co-author of a the study.

      “This is one of the first studies that identifies the causal effect of remote work on vehicle miles traveled and transit ridership across the U.S.,” adds Jinhua Zhao, an MIT professor and another co-author of the paper.

      By accounting for many of the nuances of the issue, across the lower 48 states and the District of Columbia as well as 217 metropolitan areas, the scholars believe they have arrived at a robust conclusion demonstrating the effects of working from home on larger mobility patterns.

      The paper, “Impacts of remote work on vehicle miles traveled and transit ridership in the USA,” appears today in the journal Nature Cities. The authors are Zheng, a doctoral graduate of MIT’s Department of Civil and Environmental Engineering and a postdoc at the Singapore–MIT Alliance for Research and Technology (SMART); Shenhao Wang PhD ’20, an assistant professor at the University of Florida; Lun Liu, an assistant professor at Peking University; Jim Aloisi, a lecturer in MIT’s Department of Urban Studies and Planning (DUSP); and Zhao, the Professor of Cities and Transportation, founder of the MIT Mobility Initiative, and director of MIT’s JTL Urban Mobility Lab and Transit Lab.

      The researchers gathered data on the prevalence of remote work from multiple sources, including Google location data, travel data from the U.S. Federal Highway Administration and the National Transit Database, and the monthly U.S. Survey of Working Arrangements and Attitudes (run jointly by Stanford University, the University of Chicago, ITAM, and MIT).

      The study reveals significant variation among U.S. states when it comes to how much the rise of remote work has affected mileage driven.

      “The impact of a 1 percent change in remote work on the reduction of vehicle miles traveled in New York state is only about one-quarter of that in Texas,” Zheng observes. “There is real variation there.”

      At the same time, remote work has had the biggest effect on mass-transit revenues in places with widely used systems, with New York City, Chicago, San Francisco, Boston, and Philadelphia making up the top five hardest-hit metro areas.

      The overall effect is surprisingly consistent over time, from early 2020 through late 2022.

      “In terms of the temporal variation, we found that the effect is quite consistent across our whole study period,” Zheng says. “It’s not just significant in the early stage of the pandemic, when remote work was a necessity for many. The magnitude remains consistent into the later period, when many people have the flexibility to choose where they want to work. We think this may have long-term implications.”

      Additionally, the study estimates the impact that still larger numbers of remote workers could have on the environment and mass transit.

      “On a national basis, we estimate that a 10 percent decrease in the number of onsite workers compared to prepandemic levels will reduce the annual total vehicle-related CO2 emissions by 191.8 million metric tons,” Wang says.

      The study also projects that across the 217 metropolitan areas in the study, a 10 percent decrease in the number of onsite workers, compared to prepandemic levels, would lead to an annual loss of 2.4 billion transit trips and $3.7 billion in fare revenue — equal to roughly 27 percent of the annual transit ridership and fare revenue in 2019.

      “The substantial influence of remote work on transit ridership highlights the need for transit agencies to adapt their services accordingly, investing in services tailored to noncommuting trips and implementing more flexible schedules to better accommodate the new demand patterns,” Zhao says.

      The research received support from the MIT Energy Initiative; the Barr Foundation; the National Research Foundation, Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise program; the Research Opportunity Seed Fund 2023 from the University of Florida; and the Beijing Social Science Foundation. More

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      in Environment

      Think globally, rebuild locally

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      Building construction accounts for a huge chunk of greenhouse gas emissions: About 36 percent of carbon dioxide emissions and 40 percent of energy consumption in Europe, for instance. That’s why the European Union has developed regulations about the reuse of building materials.

      Some cities are adding more material reuse into construction already. Amsterdam, for example, is attempting to slash its raw material use by half by 2030. The Netherlands as a whole aims for a “circular economy” of completely reused materials by 2050.

      But the best way to organize the reuse of construction waste is still being determined. For one thing: Where should reusable building materials be stored before they are reused? A newly published study focusing on Amsterdam finds the optimal material reuse system for construction has many local storage “hubs” that keep materials within a few miles of where they will be needed.

      “Our findings provide a starting point for policymakers in Amsterdam to strategize land use effectively,” says Tanya Tsui, a postdoc at MIT and a co-author of the new paper. “By identifying key locations repeatedly favored across various hub scenarios, we underscore the importance of prioritizing these areas for future circular economy endeavors in Amsterdam.”

      The study adds to an emerging research area that connects climate change and urban planning.

      “The issue is where you put material in between demolition and new construction,” says Fábio Duarte, a principal researcher at MIT’s Senseable City Lab and a co-author of the new paper. “It will have huge impacts in terms of transportation. So you have to define the best sites. Should there be only one? Should we hold materials across a wide number of sites? Or is there an optimal number, even if it changes over time? This is what we examined in the paper.”

      The paper, “Spatial optimization of circular timber hubs,” is published in NPJ Nature Urban Sustainability. The authors are Tsui, who is a postdoc at the MIT Senseable Amsterdam Lab in the Amsterdam Institute for Advanced Metropolitan Solutions (AMS); Titus Venverloo, a research fellow at MIT Senseable Amsterdam Lab and AMS; Tom Benson, a researcher at the Senseable City Lab; and Duarte, who is also a lecturer in MIT’s Department of Urban Studies and Planning and the MIT Center for Real Estate.

      Numerous experts have previously studied at what scale the “circular economy” of reused materials might best operate. Some have suggested that very local circuits of materials recycling make the most sense; others have proposed that building-materials recycling will work best at a regional scale, with a radius of distribution covering 30 or more miles. Some analyses contend that global-scale reuse will be necessary to an extent.

      The current study adds to this examination of the best geographic scale for using construction materials again. Currently the storage hubs that do exist for such reused materials are chosen by individual companies, but those locations might not be optimal either economically or environmentally. 

      To conduct the study, the researchers essentially conducted a series of simulations of the Amsterdam metropolitan area, focused exclusively on timber reuse. The simulations examined how the system would work if anywhere from one to 135 timber storage hubs existed in greater Amsterdam. The modeling accounted for numerous variables, such as emissions reductions, logistical factors, and even how changing supply-and-demand scenarios would affect the viability of the reusehubs.

      Ultimately, the research found that Amsterdam’s optimal system would have 29 timber hubs, each serving a radius of about 2 miles. That setup generated 95 percent of the maximum reduction in CO2 emissions, while retaining logistical and economic benefits.

      That results also lands firmly on the side of having more localized networks for keeping construction materials in use.

      “If we have demolition happening in certain sites, then we can project where the best spots around the city are to have these circular economy hubs, as we call them,” Duarte says. “It’s not only one big hub — or one hub per construction site.”

      The study seeks to identify not only the optimal number of storage sites, but to identify where those sites might be.

      “[We hope] our research sparks discussions regarding the location and scale of circular hubs,” Tsui says. “While much attention has been given to governance aspects of the circular economy in cities, our study demonstrates the potential of utilizing location data on materials to inform decisions in urban planning.”

      The simulations also illuminated the dynamics of materials reuse. In scenarios where Amsterdam had from two to 20 timber recycling hubs, the costs involved lowered as the number of hubs increased — because having more hubs reduces transportation costs. But when the number of hubs went about 40, the system as a whole became more expensive — because each timber depot was not storing enough material to justify the land use.

      As such, the results may be of interest to climate policymakers, urban planners, and business interests getting involved in implementing the circular economy in the construction industry.

      “Ultimately,” Tsui says, “we envision our research catalyzing meaningful discussions and guiding policymakers toward more informed decisions in advancing the circular economy agenda in urban contexts.”

      The research was supported, in part, by the European Union’s Horizon 2020 research and innovation program. More

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      in Energy

      Local journalism is a critical “gate” to engage Americans on climate change

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      Last year, Pew Research Center data revealed that only 37 percent of Americans said addressing climate change should be a top priority for the president and Congress. Furthermore, climate change was ranked 17th out of 21 national issues included in a Pew survey. 

      But in reality, it’s not that Americans don’t care about climate change, says celebrated climate scientist and communicator MIT Professor Katharine Hayhoe. It’s that they don’t know that they already do. 

      To get Americans to care about climate change, she adds, it’s imperative to guide them to their gate. At first, it might not be clear where that gate is. But it exists. 

      That message was threaded through the Connecting with Americans on Climate Change webinar last fall, which featured a discussion with Hayhoe and the five journalists who made up the 2023 cohort of the MIT Environmental Solutions Journalism Fellowship. Hayhoe referred to a “gate” as a conversational entry point about climate impacts and solutions. The catch? It doesn’t have to be climate-specific. Instead, it can focus on the things that people already hold close to their heart.

      “If you show people … whether it’s a military veteran or a parent or a fiscal conservative or somebody who is in a rural farming area or somebody who loves kayaking or birds or who just loves their kids … how they’re the perfect person to care [about climate change], then it actually enhances their identity to advocate for and adopt climate solutions,” said Hayhoe. “It makes them a better parent, a more frugal fiscal conservative, somebody who’s more invested in the security of their country. It actually enhances who they already are instead of trying to turn them into someone else.”

      The MIT Environmental Solutions Journalism Fellowship provides financial and technical support to journalists dedicated to connecting local stories to broader climate contexts, especially in parts of the country where climate change is disputed or underreported. 

      Climate journalism is typically limited to larger national news outlets that have the resources to employ dedicated climate reporters. And since many local papers are already struggling — with the country on track to lose a third of its papers by the end of next year, leaving over 50 percent of counties in the United States with just one or no local news outlets — local climate beats can be neglected. This makes the work executed by the ESI’s fellows all the more imperative. Because for many Americans, the relevance of these stories to their own community is their gate to climate action. 

      “This is the only climate journalism fellowship that focuses exclusively on local storytelling,” says Laur Hesse Fisher, program director at MIT ESI and founder of the fellowship. “It’s a model for engaging some of the hardest audiences to reach: people who don’t think they care much about climate change. These talented journalists tell powerful, impactful stories that resonate directly with these audiences.”

      From March to June, the second cohort of ESI Journalism Fellows pursued local, high-impact climate reporting in Montana, Arizona, Maine, West Virginia, and Kentucky. 

      Collectively, their 26 stories had over 70,000 direct visits on their host outlets’ websites as of August 2023, gaining hundreds of responses from local voters, lawmakers, and citizen groups. Even though they targeted local audiences, they also had national appeal, as they were republished by 46 outlets — including Vox, Grist, WNYC, WBUR, the NPR homepage, and three separate stories on NPR’s “Here & Now” program, which is broadcast by 45 additional partner radio stations across the country — with a collective reach in the hundreds of thousands. 

      Micah Drew published an eight-part series in The Flathead Beacon titled, “Montana’s Climate Change Lawsuit.” It followed a landmark case of 16 young people in Montana suing the state for violating their right to a “clean and healthful environment.” Of the plaintiffs, Drew said, “They were able to articulate very clearly what they’ve seen, what they’ve lived through in a pretty short amount of life. Some of them talked about wildfires — which we have a lot of here in Montana — and [how] wildfire smoke has canceled soccer games at the high school level. It cancels cross-country practice; it cancels sporting events. I mean, that’s a whole section of your livelihood when you’re that young that’s now being affected.”

      Joan Meiners is a climate news reporter for the Arizona Republic. Her five-part series was situated at the intersection of Phoenix’s extreme heat and housing crises. “I found that we are building three times more sprawling, single-family detached homes … as the number of apartment building units,” she says. “And with an affordability crisis, with a climate crisis, we really need to rethink that. The good news, which I also found through research for this series … is that Arizona doesn’t have a statewide building code, so each municipality decides on what they’re going to require builders to follow … and there’s a lot that different municipalities can do just by showing up to their city council meetings [and] revising the building codes.”

      For The Maine Monitor, freelance journalist Annie Ropeik generated a four-part series, called “Hooked on Heating Oil,” on how Maine came to rely on oil for home heating more than any other state. When asked about solutions, Ropeik says, “Access to fossil fuel alternatives was really the central equity issue that I was looking at in my project, beyond just, ‘Maine is really relying on heating oil, that obviously has climate impacts, it’s really expensive.’ What does that mean for people in different financial situations, and what does that access to solutions look like for those different communities? What are the barriers there and how can we address those?”

      Energy and environment reporter Mike Tony created a four-part series in The Charleston Gazette-Mail on West Virginia’s flood vulnerabilities and the state’s lack of climate action. On connecting with audiences, Tony says, “The idea was to pick a topic like flooding that really affects the whole state, and from there, use that as a sort of an inroad to collect perspectives from West Virginians on how it’s affecting them. And then use that as a springboard to scrutinizing the climate politics that are precluding more aggressive action.”

      Finally, Ryan Van Velzer, Louisville Public Media’s energy and environment reporter, covered the decline of Kentucky’s fossil fuel industry and offered solutions for a sustainable future in a four-part series titled, “Coal’s Dying Light.” For him, it was “really difficult to convince people that climate change is real when the economy is fundamentally intertwined with fossil fuels. To a lot of these people, climate change, and the changes necessary to mitigate climate change, can cause real and perceived economic harm to these communities.” 

      With these projects in mind, someone’s gate to caring about climate change is probably nearby — in their own home, community, or greater region. 

      It’s likely closer than they think. 

      To learn more about the next fellowship cohort — which will support projects that report on climate solutions being implemented locally and how they reduce emissions while simultaneously solving pertinent local issues — sign up for the MIT Environmental Solutions Initiative newsletter. Questions about the fellowship can be directed to Laur Hesse Fisher at climate@mit.edu. More

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      in Environment

      3 Questions: How are cities managing record-setting temperatures?

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      July 2023 was the hottest month globally since humans began keeping records. People all over the U.S. experienced punishingly high temperatures this summer. In Phoenix, there were a record-setting 31 consecutive days with a high temperature of 110 degrees Fahrenheit or more. July was the hottest month on record in Miami. A scan of high temperatures around the country often yielded some startlingly high numbers: Dallas, 110 F; Reno, 108 F; Salt Lake City, 106 F; Portland, 105 F.

      Climate change is a global and national crisis that cannot be solved by city governments alone, but cities suffering from it can try to enact new policies reducing emissions and adapting its effects. MIT’s David Hsu, an associate professor of urban and environmental planning, is an expert on metropolitan and regional climate policy. In one 2017 paper, Hsu and some colleagues estimated how 11 major U.S. cities could best reduce their carbon dioxide emissions, through energy-efficient home construction and retrofitting, improvements in vehicle gas mileage, more housing density, robust transit systems, and more. As we near the end of this historically hot summer, MIT News talked to Hsu about what cities are now doing in response to record heat, and the possibilities for new policy measures.

      Q: We’ve had record-setting temperatures in many cities across the U.S. this summer. Dealing with climate change certainly isn’t just the responsibility of those cities, but what have they been doing to make a difference, to the extent they can?

      A: I think this is a very top-of-mind question because even 10 or 15 years ago, we talked about adapting to a changed climate future, which seemed further off. But literally every week this summer we can refer to [dramatic] things that are already happening, clearly linked to climate change, and are going to get worse. We had wildfire smoke in the Northeast and throughout the Eastern Seaboard in June, this tragic wildfire in Hawaii that led to more deaths than any other wildfire in the U.S., [plus record high temperatures]. A lot of city leaders face climate challenges they thought were maybe 20 or 30 years in the future, and didn’t expect to see happen with this severity and intensity.

      One thing you’re seeing is changes in governance. A lot of cities have recently appointed a chief heat officer. Miami and Phoenix have them now, and this is someone responsible for coordinating response to heat waves, which turn out to be one of the biggest killers among climatological effects. There is an increasing realization not only among local governments, but insurance companies and the building industry, that flooding is going to affect many places. We have already seen flooding in the seaport area in Boston, the most recently built part of our city. In some sense just the realization among local governments, insurers, building owners, and residents, that some risks are here and now, already is changing how people think about those risks.

      Q: To what extent does a city being active about climate change at least signal to everyone, at the state or national level, that we have to do more? At the same time, some states are reacting against cities that are trying to institute climate initiatives and trying to prevent clean energy advances. What is possible at this point?

      A: We have this very large, heterogeneous and polarized country, and we have differences between states and within states in how they’re approaching climate change. You’ve got some cities trying to enact things like natural gas bans, or trying to limit greenhouse gas emissions, with some state governments trying to preempt them entirely. I think cities have a role in showing leadership. But one thing I harp on, having worked in city government myself, is that sometimes in cities we can be complacent. While we pride ourselves on being centers of innovation and less per-capita emissions — we’re using less than rural areas, and you’ll see people celebrating New York City as the greenest in the world — cities are responsible for consumption that produces a majority of emissions in most countries. If we’re going to decarbonize society, we have to get to zero altogether, and that requires cities to act much more aggressively.

      There is not only a pessimistic narrative. With the Inflation Reduction Act, which is rapidly accelerating the production of renewable energy, you see many of those subsidies going to build new manufacturing in red states. There’s a possibility people will see there are plenty of better paying, less dangerous jobs in [clean energy]. People don’t like monopolies wherever they live, so even places people consider fairly conservative would like local control [of energy], and that might mean greener jobs and lower prices. Yes, there is a doomscrolling loop of thinking polarization is insurmountable, but I feel surprisingly optimistic sometimes.

      Large parts of the Midwest, even in places people think of as being more conservative, have chosen to build a lot of wind energy, partly because it’s profitable. Historically, some farmers were self-reliant and had wind power before the electrical grid came. Even now in some places where people don’t want to address climate change, they’re more than happy to have wind power.

      Q: You’ve published work on which cities can pursue which policies to reduce emissions the most: better housing construction, more transit, more fuel-efficient vehicles, possibly higher housing density, and more. The exact recipe varies from place to place. But what are the common threads people can think about?

      A: It’s important to think about what the status quo is, and what we should be preparing for. The status quo simply doesn’t serve large parts of the population right now. Heat risk, flooding, and wildfires all disproportionately affect populations that are already vulnerable. If you’re elderly, or lack access to mobility, information, or warnings, you probably have a lower risk of surviving a wildfire. Many people do not have high-quality housing, and may be more exposed to heat or smoke. We know the climate has already changed, and is going to change more, but we have failed to prepare for foreseeable changes that already here. Lots of things that are climate-related but not only about climate change, like affordable housing, transportation, energy access for everyone so they can have services like cooking and the internet — those are things that we can change going forward. The hopeful message is: Cities are always changing and being built, so we should make them better. The urgent message is: We shouldn’t accept the status quo. More

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      in Environment

      Helping the transportation sector adapt to a changing world

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      After graduating from college, Nick Caros took a job as an engineer with a construction company, helping to manage the building of a new highway bridge right near where he grew up outside of Vancouver, British Columbia.  

      “I had a lot of friends that would use that new bridge to get to work,” Caros recalls. “They’d say, ‘You saved me like 20 minutes!’ That’s when I first realized that transportation could be a huge benefit to people’s lives.”

      Now a PhD candidate in the Urban Mobility Lab and the lead researcher for the MIT Transit Research Consortium, Caros works with seven transit agencies across the country to understand how workers’ transportation needs have changed as companies have adopted remote work policies.

      “Another cool thing about working on transportation is that everybody, even if they don’t engage with it on an academic level, has an opinion or wants to talk about it,” says Caros. “As soon as I mention I’ve worked with the T, they have something they want to talk about.”

      Caros is drawn to projects with social impact beyond saving his friends a few minutes during their commutes. He sees public transportation as a crucial component in combating climate change and is passionate about identifying and lowering the psychological barriers that prevent people around the world from taking advantage of their local transit systems.

      “The more I’ve learned about public transportation, the more I’ve come to realize it will play an essential part in decarbonizing urban transportation,” says Caros. “I want to continue working on these kinds of issues, like how we can make transportation more sustainable or promoting public transportation in places where it doesn’t exist or can be improved.”

      Caros says he doesn’t have a “transportation origin story,” like some of his peers who grew up in urban centers with robust public transit systems. As a child growing up in the Vancouver suburbs, he always enjoyed the outdoors, which were as close as his backyard. He chose to study engineering as an undergraduate at the University of British Columbia, fascinated by the hydroelectric dams that supply Vancouver with most of its power. But after two projects with the construction company, the second of which took him to Maryland to work on a fossil fuel project, he decided he needed a change.

      Not quite sure what he wanted to do next, Caros sought out the shortest master’s program he could find that interested him. That ended up being an 18-month master’s program in transportation planning and engineering at New York University. Initially intending to pursue the course-based program, Caros was soon offered the chance to be a research assistant in NYU’s Behavioral Urban Informatics, Logistics, and Transport Laboratory with Professor Joseph Chow. There, he worked to model an experimental transportation system of modular self-driving cars that could link and unlink with each other while in motion.

      “It was this really futuristic stuff,” says Caros. “It turned out to be a really cool project to work on because it’s kind of rare to have a blank-slate problem to try and solve. A lot of transportation engineering problems have largely been solved. We know how to make efficient and sustainable transportation systems; it’s just finding the political support and encouraging behavioral change that remains a challenge.”

      At NYU, Caros fell in love with research and the field of transportation. Later, he was drawn to MIT by its interdisciplinary PhD program that spans both urban studies and planning and civil engineering and the opportunity to work with Professor Jinhua Zhao.

      His research focuses on identifying “third places,” locations where some people go if their job gives them the flexibility to work remotely. Previously, transportation needs revolved around office spaces, typically located in city centers. With more people working from home, the first assumption is that transportation needs would decrease. But that’s not what Caros has found.

      “One major finding from our research is that people have changed where they’re going when they go to work,” says Caros. “A lot of people are working from home, but some are also working in other places, like coffee shops or co-working spaces. And these third places are not evenly distributed in Boston.”

      Identifying the concentration of these third places and what locations would benefit from them is the core of Caros’ dissertation. He’s building an algorithm that identifies ideal locations to build more shared workplaces based on both economic and social factors. Caros seeks to answer how you can minimize travel time across the board while leaving room for the spontaneous social interactions that drive a city’s productivity. His research is sponsored by seven of the largest transit agencies in the United States, who are members of the MIT Transit Research Consortium. Rather than a single agency sponsoring a single specific project, funding is pooled to tackle projects that address general topics that can apply to multiple cities.

      These kinds of problems require a multidisciplinary approach that appeals to Caros. Even when diving into the technical details of a solution, he always keeps the bigger picture in mind. He is certain that changing people’s views of public transportation will be crucial in the fight against climate change.

      “A lot of it is not necessarily engineering, but understanding what the motivations of people are,” says Caros. “Transportation is a leading sector for carbon emissions in the U.S., and so figuring out what makes people tick and how you can get them to ride public transit more, for example, would help to reduce the overall carbon cost.”

      Following the completion of his degree, Caros will join the Organization for Economic Cooperation and Development. He already spent six months at its Paris headquarters as an intern during a leave from MIT, something his lab encourages all of its students to do. Last fall, he worked on drafting policy guidelines for new mobility services such as vehicle-share scooters, and addressing transportation equity issues in Ghana. Plus, living in Paris gave him the opportunity to practice his French. Growing up in Canada, he attended a French immersion school, and his internship offered his first opportunity to use the language outside of an academic context.

      Looking forward, Caros hopes to keep tackling projects that promote sustainable public transportation. There is an urgency in getting ahead of the curve, especially in cities experiencing rapid growth.

      “You kind of get locked in,” says Caros. “It becomes much harder to build sustainable transportation systems after the fact. But it’s really just a geometry problem. Trains and buses are a way more efficient way to move people using the same amount of space as private cars.” More

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      in Energy

      Cutting urban carbon emissions by retrofitting buildings

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      To support the worldwide struggle to reduce carbon emissions, many cities have made public pledges to cut their carbon emissions in half by 2030, and some have promised to be carbon neutral by 2050. Buildings can be responsible for more than half a municipality’s carbon emissions. Today, new buildings are typically designed in ways that minimize energy use and carbon emissions. So attention focuses on cleaning up existing buildings.

      A decade ago, leaders in some cities took the first step in that process: They quantified their problem. Based on data from their utilities on natural gas and electricity consumption and standard pollutant-emission rates, they calculated how much carbon came from their buildings. They then adopted policies to encourage retrofits, such as adding insulation, switching to double-glazed windows, or installing rooftop solar panels. But will those steps be enough to meet their pledges?

      “In nearly all cases, cities have no clear plan for how they’re going to reach their goal,” says Christoph Reinhart, a professor in the Department of Architecture and director of the Building Technology Program. “That’s where our work comes in. We aim to help them perform analyses so they can say, ‘If we, as a community, do A, B, and C to buildings of a certain type within our jurisdiction, then we are going to get there.’”

      To support those analyses, Reinhart and a team in the MIT Sustainable Design Lab (SDL) — PhD candidate Zachary M. Berzolla SM ’21; former doctoral student Yu Qian Ang PhD ’22, now a research collaborator at the SDL; and former postdoc Samuel Letellier-Duchesne, now a senior building performance analyst at the international building engineering and consulting firm Introba — launched a publicly accessible website providing a series of simulation tools and a process for using them to determine the impacts of planned steps on a specific building stock. Says Reinhart: “The takeaway can be a clear technology pathway — a combination of building upgrades, renewable energy deployments, and other measures that will enable a community to reach its carbon-reduction goals for their built environment.”

      Analyses performed in collaboration with policymakers from selected cities around the world yielded insights demonstrating that reaching current goals will require more effort than city representatives and — in a few cases — even the research team had anticipated.

      Exploring carbon-reduction pathways

      The researchers’ approach builds on a physics-based “building energy model,” or BEM, akin to those that architects use to design high-performance green buildings. In 2013, Reinhart and his team developed a method of extending that concept to analyze a cluster of buildings. Based on publicly available geographic information system (GIS) data, including each building’s type, footprint, and year of construction, the method defines the neighborhood — including trees, parks, and so on — and then, using meteorological data, how the buildings will interact, the airflows among them, and their energy use. The result is an “urban building energy model,” or UBEM, for a neighborhood or a whole city.

      The website developed by the MIT team enables neighborhoods and cities to develop their own UBEM and to use it to calculate their current building energy use and resulting carbon emissions, and then how those outcomes would change assuming different retrofit programs or other measures being implemented or considered. “The website — UBEM.io — provides step-by-step instructions and all the simulation tools that a team will need to perform an analysis,” says Reinhart.

      The website starts by describing three roles required to perform an analysis: a local sustainability champion who is familiar with the municipality’s carbon-reduction efforts; a GIS manager who has access to the municipality’s urban datasets and maintains a digital model of the built environment; and an energy modeler — typically a hired consultant — who has a background in green building consulting and individual building energy modeling.

      The team begins by defining “shallow” and “deep” building retrofit scenarios. To explain, Reinhart offers some examples: “‘Shallow’ refers to things that just happen, like when you replace your old, failing appliances with new, energy-efficient ones, or you install LED light bulbs and weatherstripping everywhere,” he says. “‘Deep’ adds to that list things you might do only every 20 years, such as ripping out walls and putting in insulation or replacing your gas furnace with an electric heat pump.”

      Once those scenarios are defined, the GIS manager uploads to UBEM.io a dataset of information about the city’s buildings, including their locations and attributes such as geometry, height, age, and use (e.g., commercial, retail, residential). The energy modeler then builds a UBEM to calculate the energy use and carbon emissions of the existing building stock. Once that baseline is established, the energy modeler can calculate how specific retrofit measures will change the outcomes.

      Workshop to test-drive the method

      Two years ago, the MIT team set up a three-day workshop to test the website with sample users. Participants included policymakers from eight cities and municipalities around the world: namely, Braga (Portugal), Cairo (Egypt), Dublin (Ireland), Florianopolis (Brazil), Kiel (Germany), Middlebury (Vermont, United States), Montreal (Canada), and Singapore. Taken together, the cities represent a wide range of climates, socioeconomic demographics, cultures, governing structures, and sizes.

      Working with the MIT team, the participants presented their goals, defined shallow- and deep-retrofit scenarios for their city, and selected a limited but representative area for analysis — an approach that would speed up analyses of different options while also generating results valid for the city as a whole.

      They then performed analyses to quantify the impacts of their retrofit scenarios. Finally, they learned how best to present their findings — a critical part of the exercise. “When you do this analysis and bring it back to the people, you can say, ‘This is our homework over the next 30 years. If we do this, we’re going to get there,’” says Reinhart. “That makes you part of the community, so it’s a joint goal.”

      Sample results

      After the close of the workshop, Reinhart and his team confirmed their findings for each city and then added one more factor to the analyses: the state of the city’s electric grid. Several cities in the study had pledged to make their grid carbon-neutral by 2050. Including the grid in the analysis was therefore critical: If a building becomes all-electric and purchases its electricity from a carbon-free grid, then that building will be carbon neutral — even with no on-site energy-saving retrofits.

      The final analysis for each city therefore calculated the total kilograms of carbon dioxide equivalent emitted per square meter of floor space assuming the following scenarios: the baseline; shallow retrofit only; shallow retrofit plus a clean electricity grid; deep retrofit only; deep retrofit plus rooftop photovoltaic solar panels; and deep retrofit plus a clean electricity grid. (Note that “clean electricity grid” is based on the area’s most ambitious decarbonization target for their power grid.)

      The following paragraphs provide highlights of the analyses for three of the eight cities. Included are the city’s setting, emission-reduction goals, current and proposed measures, and calculations of how implementation of those measures would affect their energy use and carbon emissions.

      Singapore

      Singapore is generally hot and humid, and its building energy use is largely in the form of electricity for cooling. The city is dominated by high-rise buildings, so there’s not much space for rooftop solar installations to generate the needed electricity. Therefore, plans for decarbonizing the current building stock must involve retrofits. The shallow-retrofit scenario focuses on installing energy-efficient lighting and appliances. To those steps, the deep-retrofit scenario adds adopting a district cooling system. Singapore’s stated goals are to cut the baseline carbon emissions by about a third by 2030 and to cut it in half by 2050.

      The analysis shows that, with just the shallow retrofits, Singapore won’t achieve its 2030 goal. But with the deep retrofits, it should come close. Notably, decarbonizing the electric grid would enable Singapore to meet and substantially exceed its 2050 target assuming either retrofit scenario.

      Dublin

      Dublin has a mild climate with relatively comfortable summers but cold, humid winters. As a result, the city’s energy use is dominated by fossil fuels, in particular, natural gas for space heating and domestic hot water. The city presented just one target — a 40 percent reduction by 2030.

      Dublin has many neighborhoods made up of Georgian row houses, and, at the time of the workshop, the city already had a program in place encouraging groups of owners to insulate their walls. The shallow-retrofit scenario therefore focuses on weatherization upgrades (adding weatherstripping to windows and doors, insulating crawlspaces, and so on). To that list, the deep-retrofit scenario adds insulating walls and installing upgraded windows. The participants didn’t include electric heat pumps, as the city was then assessing the feasibility of expanding the existing district heating system.

      Results of the analyses show that implementing the shallow-retrofit scenario won’t enable Dublin to meet its 2030 target. But the deep-retrofit scenario will. However, like Singapore, Dublin could make major gains by decarbonizing its electric grid. The analysis shows that a decarbonized grid — with or without the addition of rooftop solar panels where possible — could more than halve the carbon emissions that remain in the deep-retrofit scenario. Indeed, a decarbonized grid plus electrification of the heating system by incorporating heat pumps could enable Dublin to meet a future net-zero target.

      Middlebury

      Middlebury, Vermont, has warm, wet summers and frigid winters. Like Dublin, its energy demand is dominated by natural gas for heating. But unlike Dublin, it already has a largely decarbonized electric grid with a high penetration of renewables.

      For the analysis, the Middlebury team chose to focus on an aging residential neighborhood similar to many that surround the city core. The shallow-retrofit scenario calls for installing heat pumps for space heating, and the deep-retrofit scenario adds improvements in building envelopes (the façade, roof, and windows). The town’s targets are a 40 percent reduction from the baseline by 2030 and net-zero carbon by 2050.

      Results of the analyses showed that implementing the shallow-retrofit scenario won’t achieve the 2030 target. The deep-retrofit scenario would get the city to the 2030 target but not to the 2050 target. Indeed, even with the deep retrofits, fossil fuel use remains high. The explanation? While both retrofit scenarios call for installing heat pumps for space heating, the city would continue to use natural gas to heat its hot water.

      Lessons learned

      For several policymakers, seeing the results of their analyses was a wake-up call. They learned that the strategies they had planned might not be sufficient to meet their stated goals — an outcome that could prove publicly embarrassing for them in the future.

      Like the policymakers, the researchers learned from the experience. Reinhart notes three main takeaways.

      First, he and his team were surprised to find how much of a building’s energy use and carbon emissions can be traced to domestic hot water. With Middlebury, for example, even switching from natural gas to heat pumps for space heating didn’t yield the expected effect: On the bar graphs generated by their analyses, the gray bars indicating carbon from fossil fuel use remained. As Reinhart recalls, “I kept saying, ‘What’s all this gray?’” While the policymakers talked about using heat pumps, they were still going to use natural gas to heat their hot water. “It’s just stunning that hot water is such a big-ticket item. It’s huge,” says Reinhart.

      Second, the results demonstrate the importance of including the state of the local electric grid in this type of analysis. “Looking at the results, it’s clear that if we want to have a successful energy transition, the building sector and the electric grid sector both have to do their homework,” notes Reinhart. Moreover, in many cases, reaching carbon neutrality by 2050 would require not only a carbon-free grid but also all-electric buildings.

      Third, Reinhart was struck by how different the bar graphs presenting results for the eight cities look. “This really celebrates the uniqueness of different parts of the world,” he says. “The physics used in the analysis is the same everywhere, but differences in the climate, the building stock, construction practices, electric grids, and other factors make the consequences of making the same change vary widely.”

      In addition, says Reinhart, “there are sometimes deeply ingrained conflicts of interest and cultural norms, which is why you cannot just say everybody should do this and do this.” For instance, in one case, the city owned both the utility and the natural gas it burned. As a result, the policymakers didn’t consider putting in heat pumps because “the natural gas was a significant source of municipal income, and they didn’t want to give that up,” explains Reinhart.

      Finally, the analyses quantified two other important measures: energy use and “peak load,” which is the maximum electricity demanded from the grid over a specific time period. Reinhart says that energy use “is probably mostly a plausibility check. Does this make sense?” And peak load is important because the utilities need to keep a stable grid.

      Middlebury’s analysis provides an interesting look at how certain measures could influence peak electricity demand. There, the introduction of electric heat pumps for space heating more than doubles the peak demand from buildings, suggesting that substantial additional capacity would have to be added to the grid in that region. But when heat pumps are combined with other retrofitting measures, the peak demand drops to levels lower than the starting baseline.

      The aftermath: An update

      Reinhart stresses that the specific results from the workshop provide just a snapshot in time; that is, where the cities were at the time of the workshop. “This is not the fate of the city,” he says. “If we were to do the same exercise today, we’d no doubt see a change in thinking, and the outcomes would be different.”

      For example, heat pumps are now familiar technology and have demonstrated their ability to handle even bitterly cold climates. And in some regions, they’ve become economically attractive, as the war in Ukraine has made natural gas both scarce and expensive. Also, there’s now awareness of the need to deal with hot water production.

      Reinhart notes that performing the analyses at the workshop did have the intended impact: It brought about change. Two years after the project had ended, most of the cities reported that they had implemented new policy measures or had expanded their analysis across their entire building stock. “That’s exactly what we want,” comments Reinhart. “This is not an academic exercise. It’s meant to change what people focus on and what they do.”

      Designing policies with socioeconomics in mind

      Reinhart notes a key limitation of the UBEM.io approach: It looks only at technical feasibility. But will the building owners be willing and able to make the energy-saving retrofits? Data show that — even with today’s incentive programs and subsidies — current adoption rates are only about 1 percent. “That’s way too low to enable a city to achieve its emission-reduction goals in 30 years,” says Reinhart. “We need to take into account the socioeconomic realities of the residents to design policies that are both effective and equitable.”

      To that end, the MIT team extended their UBEM.io approach to create a socio-techno-economic analysis framework that can predict the rate of retrofit adoption throughout a city. Based on census data, the framework creates a UBEM that includes demographics for the specific types of buildings in a city. Accounting for the cost of making a specific retrofit plus financial benefits from policy incentives and future energy savings, the model determines the economic viability of the retrofit package for representative households.

      Sample analyses for two Boston neighborhoods suggest that high-income households are largely ineligible for need-based incentives or the incentives are insufficient to prompt action. Lower-income households are eligible and could benefit financially over time, but they don’t act, perhaps due to limited access to information, a lack of time or capital, or a variety of other reasons.

      Reinhart notes that their work thus far “is mainly looking at technical feasibility. Next steps are to better understand occupants’ willingness to pay, and then to determine what set of federal and local incentive programs will trigger households across the demographic spectrum to retrofit their apartments and houses, helping the worldwide effort to reduce carbon emissions.”

      This work was supported by Shell through the MIT Energy Initiative. Zachary Berzolla was supported by the U.S. National Science Foundation Graduate Research Fellowship. Samuel Letellier-Duchesne was supported by the postdoctoral fellowship of the Natural Sciences and Engineering Research Council of Canada.

      This article appears in the Spring 2023 issue of Energy Futures, the magazine of the MIT Energy Initiative. More