With increasing construction and demolition waste, the demand for recycled concrete aggregates (RCA) has risen, yet their inherent poor-quality limits usage. In response, CO2 treatment has been developed to enhance RCA quality while contributing to CO2 reduction efforts. This study investigates the effect of CO2 treatment on RCA with high mortar contents for sustainable construction applications. Treatment conditions were optimized by evaluating the CO2 consumption ratio and reaction kinetics under various temperatures (10–50°C), pressures (250–1000 kPa), relative humidity (30–70%), and initial saturation (30–100%). X-ray imaging confirms carbonation within the mortar, evidenced by increased grey values. Environmental assessment of leachate reveals a significant reduction in chromium concentration from 0.18 mg/L to 0.11 mg/L and a decrease in pH from 10.1 to 7.8 after CO2 treatment, suggesting the potential of CO2 conditioning to mitigate the environmental impacts. Mechanical tests, the aggregate crushing value (ACV) test, and the freeze-thaw (FT) resistance test demonstrate improved resistance and durability, with a decrease in ACV from 35.5% to 33.2% and FT mass loss from 25.1% to 20.0%. The life cycle assessment analysis shows that a simplified CO2 treatment achieved a significant reduction of 138.257 kg CO2 eq per ton of RCA compared to the conventional RCA process. These findings highlight the dual benefits of CO2 treatment: enhanced mechanical performance and reduced environmental impact, promoting the use of recycled aggregates in sustainable construction practices.

The Intergovernmental Panel on Climate Change (IPCC) ambitious goal of achieving carbon neutrality by 2050 has been embraced by a variety of countries including South Korea. In South Korea, an increasingly vital neutrality strategy is enhancing carbon absorption through land use planning. A key consideration in these strategies is the comprehensive evaluation of carbon sinks present in various land cover categories. These carbon sinks—most notably forests, grasslands, and wetlands—play a critical role in mitigating the effects of climate change by locking carbon dioxide out of the atmosphere. However, forests and grasslands have long been prime avenues for new exurban development. This study analyzes the effects of large-scale development across several key carbon sinks for the Seoul Metropolitan Area of South Korea. Our findings indicate that the key carbon sinks increased from 2007 to 2021. Regardless, urban development has flourished where greenbelts were released, leading to significant depletion of forests, grasslands, and wetlands. However, converting farmland to New Town developments with massive park systems has contributed to an increase in carbon sinks in some parts of the region. In the perspective of South Korea’s goals for carbon neutrality, absorption is insufficient. Therefore, it is necessary to reflect the loss of sinks as a cost of sprawl and frame policies to expand storage through afforestation or reassessment of idle, undeveloped land.

Over the past decade, the number of patients with heat-related illnesses has steeply increased in South Korea. South Korea’s main heat adaptation planning revolves around providing cooling shelters, mostly in the form of elderly centers, to those who cannot afford adequate cooling resources. While implementing such a policy is important, it is also important to evaluate the effectiveness of existing policies to derive useful planning implications for future heat adaptation planning. Controlling for the spatial autocorrelation of residuals using the Generalized Least Squares (GLS), we found that the cooling centers in Seoul are overall well-distributed which was attributable to the local heat response policies. However, cooling shelters have been mostly designated in senior shelters lacking mainstream discussion that heat vulnerability can be influenced by much diverse factors than age.

Winter Storm Uri hit Texas in February 2021, leaving millions of people without power. This winter storm and energy crisis provide an example of failed climate planning but present an opportunity to understand response and resiliency during climate change-related events in Texas. Comparing the impacts experienced by the public to communications of elected officials and utility providers could help us understand whether their responses were sufficient enough to address the needs of the communities during the disaster. We performed text content analyses on Twitter data collected from San Antonio’s elected officials, utility providers, and the public during the pre- and post-disaster periods. The results demonstrate three major outcomes: 1) elected officials' Twitter activities spiked during the storm which focused on warnings, resources, and situation updates but not so much on recovery, 2) while the public discussed the storm concerning climate change, climate change was largely missing from the elected officials’ and utility providers’ tweets, and lastly 3) communications did not lead to sufficient action to prepare for future climate change-related crises. 

Many governments, businesses, and institutions are committing to net zero greenhouse gas emissions by 2050, a goal and process known as deep decarbonization. Achieving this goal in the United States requires a national, economy-wide transformation in energy production and use in five sectors: electricity, transportation, industry, land-based carbon sinks, and buildings. All of these sectors interact with planning for the built environment and land use, so planning scholars and practitioners have many opportunities to engage policymakers working on national-level decarbonization strategies. This article analyzes the consequences of deep decarbonization for the future speed, scale, scope, role, and relevance of planning. 

Greenbelts are large areas of open land close to cities and suburbs and are found in several countries, including the US. The basic purposes of a greenbelt are to limit the extension of urban growth into the countryside as well as to protect and preserve farmland, forestland, and natural areas. Recently, the value of greenbelts has been recognized for providing carbon sinks to store and sequester carbon. We analyze the performance of six greenbelt counties in limiting sprawl and retaining open land. We then compare six counties with greenbelts to 19 adjacent counties without greenbelts to show that greenbelt counties experienced less land conversion from 2006 to 2016. Next, we calculate the conversion of the land by four land cover types in the six greenbelt counties. Finally, we analyze the conversion of land cover types by their carbon storage and sequestration capacity to indicate which land cover types different counties should prioritize for protection and preservation in their greenbelts. 

Campus district energy (DE) systems present opportunities to reduce energy costs, reduce greenhouse gas emissions, manage peak loads, and increase the share of renewable energy. We investigate the opportunities and barriers to expanding campus DE systems off-campus through surveys and interviews with 18 campus DE managers and providers, and a case study modeling heat demand near campus. The impact of DEs on buildings’ energy consumption reductions are estimated at around 33%. Expanding the campus DE systems to nearby buildings may yield similar energy efficiency gains off-campus. However, about half the survey respondents do not see off-campus DE expansions as currently possible. Barriers to extension include high infrastructure installation costs, stringent utility regulations, insufficient financial and institutional incentives, and individualistic mentalities whereby building owners prefer to control their energy systems. 

This article explores the possibility that pairing desirable community amenities with polluting, industrial, or otherwise unwanted sites, such as waste incinerators, may have the potential to mitigate, or even compensate for, some of their negative local impacts. The environmental justice literature shows that polluting sites tend to disproportionately affect low income and disenfranchised communities. Could this be reversed or mitigated by linking positive amenities to polluting sites? The South Korean experiment of building community amenities (recreation centers, pools, gyms, etc.) at waste incinerators may provide answers to this intriguing question. Using the Difference-in-Differences design we found that while incinerators without amenities have substantial negative impacts on local land and real estate markets, we did not observe any such impact in areas with incinerators that have amenity features. Thus, the amenity features of the incinerators (along with enhanced regulatory emissions standards) are mitigating the negative economic impacts of incinerators. 

Buildings and energy systems are shaped within many different kinds of departments and agencies throughout local governments. This article argues that further opportunities exist to reduce the energy use of buildings and their associated greenhouse gas (GHG) emissions through the existing powers and jurisdiction of local governments. We use the example of New York City, where buildings produced 73 percent of all GHG emissions in 2014. By analyzing a data set of almost four thousand large buildings, we identify new opportunities for planners and other professionals to reduce energy use and GHG emissions by focusing on different mechanisms and/or collaborations. 

A growing number of governments have begun to implement benchmarking or energy disclosure policies. By requiring owners to measure and disclose their energy use, these policies are intended to transform the market for energy-efficient investments in existing buildings. To improve future policy efforts, two critical questions are: first, how much energy do these policies save? and second, what particular aspects of these policies are most effective? To answer these questions, this study explores how different aspects of these policies were phased-in to different groups of buildings over the first four years of the City of New York's benchmarking ordinance. By applying a novel difference-in-differences strategy, we can causally attribute observed declines in energy consumption to specific owner behaviors and policy mechanisms. Our analysis indicates that in comparison with the control group and before the policies were implemented in 2011, total disclosure of both energy use and Energy Star together can be credited with a 6% reduction in building energy use intensity (EUI) three years later and a 14% reduction in EUI four years later. Disclosure of Energy Star scores decreased building EUI by 9% three years later and 13% four years later. These two separate findings are a consequence of the policy design and different control groups. 

This study explores the changes in the regional growth patterns in the nine largest Canadian Census Metropolitan Areas (CMAs) between 1990 and 2010. We analyzed whether the metropolitan areas matched the Inside Game (i.e., intensification) with a strong Outside Game (i.e., regional planning) of growth management as represented by physical growth patterns. Overall, Toronto, Vancouver, and London CMAs matched the Inside Game with a strong Outside Game. Conversely, the CMAs of Ottawa, Montreal, Quebec, Calgary, Edmonton, and Winnipeg, where regional governance is fragmented or absent, exhibited signs of regional sprawl. All studied CMAs but Quebec City exhibited signs of intensification. 

Since the late 1990s, Smart Growth has found broad acceptance within Canadian planning as a framework for sustainable urban development. Smart Growth emerged as a response to decades of dispersed and decentralized growth that dominated urbanization patterns in North America post-WWII. Through a series of spatial analysis methods, this research examines whether Smart Growth has influenced growth patterns of six mid-sized Canadian census metropolitan areas from 1990 to 2010. Findings of this research suggest that municipalities and regions have adopted policies consistent with Smart Growth, however, its influence on dispersed patterns of spatial growth has been limited. 

The Calgary Metropolitan Area experienced unprecedented growth between 1991 and 2011, becoming the most densifying metropolitan area in Canada. New developments during this period were concentrated in the city edge and exurban areas in parallel with the population growth and occurred contiguously to the existing urban areas. Local growth management policies were found to be effective in densifying the inner suburban areas. However, during the same 2 decades, municipalities outside the city boundary also experienced substantial growth and a considerable increase in the number of their residents relying on automobiles to commute to jobs in Calgary, showing the sign of regional sprawl. The growth challenges of the Calgary metro were felt increasingly more regionally over the years, creating a need for stronger regional growth management. 

In this paper, we examine the merits and pitfalls of greenbelt policy by analyzing the history of greenbelt policy adoption and practice in five countries – UK, Canada, Australia, US and Korea. Despite its local implications, many greenbelt policies have been pursued and implemented at the national level, and yet few studies have incorporated the national context into understanding the scope of greenbelt policy in urban areas. A cross-national approach broadens our understanding about why greenbelt policies have achieved varying levels of success and acceptance in the urban planning process and reveals how national contexts can affect the scope of regional and local planning. Our analysis is built on a continuum across two regimes - UK as a prototype of state-controlled growth restriction regime on the one hand, and US as a prototype of the decentralized privatization regime on the other. Between these two regimes, we place hybrid cases – Canada, Australia and South Korea – that reflect a combination of characteristics in each regime. This typology not only offers a unifying framework to encompass the variants of greenbelt policies, but it also helps explain how changes might occur in strengthening or relaxing the scope of greenbelt policy. We show that although each country (or its subnational jurisdictions) maintains fairly stable greenbelt policy once it is adopted, its scope and direction is not entirely unchangeable but contingent upon the shifting political climate. 

This study analyzes the effects of relaxing the greenbelt in the Seoul Metropolitan Area of South Korea. Ordinary least squares and generalized least squares regressions were employed to measure the policy’s effect on four sprawl measurement criteria: physical growth containment, land and housing values, community service provision cost, and commuting cost. Relaxing the greenbelt guided new development inside the greenbelt and decreased the percentage change in property tax and land price relative to the urban core throughout the region. The relaxation decreased fiscal burden in areas beyond the greenbelt; however, commuting data analyses showed that the commuting costs remained high. 

Plans can only impact practice when elected officials adopt, enact, and approve funding for specific strategies. We explore ways to track implementation from the planning documents to elected officials’ priorities and to their voting patterns to identify the consistencies and gaps that may limit the impact of plans. We use Twitter data mining, text content analysis, and voting records from the digitized council minutes in Calgary, Alberta between the 2017 municipal election and the last quarter of 2020. We connect the expressed preferences to votes for each councilor over the study period. On the two most salient topics – transit and affordable housing – those who expressed support on Twitter also supported investments. With one exception of an anti-tax councilor, over time, the rest of the councilors reached agreements on public investments (supra-local funding lightened the financial burdens for the city facilitating “yes” votes). Planners can derive meaningful information from the elected officials’ social media communication, such as concerns and support for specific planning initiatives, to promote successful plan implementation. This information can also enhance voters’ awareness of local officials’ views and actions on planning initiatives.

Problem, research strategy, and findings
Local elected officials play a leadership role in setting plan directions and can jeopardize implementation if they are not committed to plan goals. In this research, we apply topic modeling, semantic networks, and sentiment analyses to Calgary’s (Canada) plans and candidates’ social media communications in the 2017 Calgary municipal election to assess alignments or divergences between plans’ and candidates’ priorities. Though the mayor, ward representatives, incumbents, and challengers prioritized different topics, we find overall support for transit infrastructure, development, and improving the downtown and the municipal tax base. However, candidates showed little interest in environmental issues, growth management, and regional cooperation, which are important plan goals that may not be addressed. The methodology has limitations: Using social media posts underrepresents the views of some candidates; text data processing may miss metaphorical phrases; elected officials’ priorities during campaigns may not determine their actual votes once in office; and this cross-sectional analysis does not capture the ever-changing relations between officials’ priorities, plan-making, and implementation.
Takeaway for practice
Candidates focused mainly on transit and taxes to the detriment of regional and environmental issues (energy, watershed, and growth management), revealing the incoming municipal administration’s priorities and its potential blind spots. Planners may use this methodology to analyze large text data from both online and offline sources, understand local implementation barriers, explain shifts in municipal policy directions, and engage elected officials to build support for important plan components.