Cities generate a large share of greenhouse gas (GHG) emissions, which directly affect global climate change. Although it has been shown that global GHGs decreased during the socio-health pandemic, local emissions saw a sharp increase. This research studied the influence of different factors on the heating and energy carbon footprint of households in cities in south-central Chile before and during the Covid-19 pandemic. By means of multiple regression models, it was shown that wood heating, low temperatures, larger dwellings and higher number of inhabitants generally explain the increase of the carbon footprint, especially in confinement. The urgency of developing integrated public policies that consider housing energy efficiency, household energy poverty and the cultural rootedness to the use of firewood in these cities is discussed.

Los cambios en la estructura espacial de las ciudades intermedias es un tema poco estudiado, a pesar del elevado porcentaje de la población que vive en ellas. Diversos estudios aplicados a grandes metrópolis han constatado que donde más crece el empleo no es ni en el centro principal ni en los subcentros, sino es en las zonas dispersas. En esta investigación se identifican y delimitan los subcentros de empleo de 17 ciudades intermedias mexicanas, para posteriormente medir la evolución del peso del empleo en el centro principal, en los subcentros y en las zonas dispersas entre los años 2000 y 2020. Los resultados obtenidos señalan que las ciudades intermedias, crecientemente descentralizadas, tienden principalmente hacia el policentrismo, lo cual presenta ventajas relevantes en términos de planificación territorial.

The COVID-19 pandemic completely transformed the mobility of cities. The restrictions on movement led to "empty cities" throughout the world, with some environmental effects in terms of clean air and the reduction of CO2 emissions. This research considers how COVID-19 mobility restrictions have affected the carbon footprint of four medium-sized Chilean cities (Coronel, Temuco, Valdivia, and Osorno) that have environmental problems and are highly dependent on motorized systems. The study uses data from 2400 household surveys at three distinct times: pre-pandemic - T0 (winter 2019), the time of implementation of restrictive mobility policies to contain the pandemic - T1 (winter 2020), and six months later when those restrictions were gradually lifted - T2 (summer 2021). The analysis suggests that CO2 emissions actually went up, declining in the winter 2020, but then increasing with the greater use of cars in the summer 2021 due to the temporary effects of commuting to work, ultimately reaching levels higher than the pre-pandemic values, known as the "rebound effect."

The coronavirus disease 2019 (COVID-19) pandemic has strongly affected economies and human lifestyles globally. The changes observed in domestic energy consumption patterns have had an impact on household greenhouse gas (GHG) emissions. Since GHG emissions inventories are only available at the country level and at annual intervals, most studies have calculated the local emission variations by extrapolating annual emissions with smaller time and territorial scale consumption data. This research presents a bottom-up method, based on the exploitation of a survey addressed to 1200 households, that provides the information to calculate directly the variation in their energy-related GHG emissions, without the need for extrapolations. This method has been applied to four medium-sized Chilean cities with serious air quality problems. Given the high correlation between atmospheric pollutants such as NOx and CO2 emissions, we estimate that before the appearance of COVID-19, per capita CO2 emissions were already high. The results show that space heating-related GHG emissions have increased moderately (between 1 and 6%), while emissions from electricity and gas consumption for non-heating uses have increased significantly (between 8 and 23%). This has harmed the household economy, highlighting the importance of considering socioeconomic aspects when assessing the impact of COVID-19 in its entirety.

Los cambios en los patrones de consumo doméstico de energía observados durante la pandemia de coronavirus 2019 (COVID-19) han tenido un impacto en las emisiones de gases de efecto invernadero (GEI) de los hogares. El documento presenta los hallazgos de una encuesta dirigida a 1200 hogares en cuatro ciudades del centro-sur de Chile, que proporciona la información para calcular directamente las emisiones de GEI relacionadas con el uso residencial de energía. Los resultados muestran que las emisiones de GEI relacionadas con la calefacción han aumentado moderadamente durante la pandemia del COVID-19 (entre el 1 y el 6%), mientras que las emisiones del consumo de electricidad y gas para usos distintos a la calefacción han aumentado significativamente (entre el 8 y el 23%). Esto ha perjudicado la economía de los hogares, destacando la importancia de considerar aspectos socioeconómicos al evaluar el impacto del COVID-19 en las emisiones de GEI de los hogares.

Different studies have estimated cities' contribution to total greenhouse gas (GHG) emissions at between forty and seventy percent. According to the so-called Compact City Approach, high density and centrality should lead to low GHG. This study compares the effect of the urban density and spatial structure (monocentrism, polycentrism, and dispersion) of the main U.S. cities on their greenhouse gas emissions from mobility and housing. The estimated models include control variables in order to improve the statistical adjustment, these variables are grouped into three categories: basic controls as temperature and Gross Domestic Product (GDP); historical-demographic controls since 1900; and geographic-urban planning controls. The results detect an environmentally positive effect, albeit a moderate one, associated with monocentric and polycentric spatial structures as compared to dispersed structures. Within the tradition of urban planning, these results can be used as an argument to stop the dispersed decentralization of cities. However, the efficacy of some policies encouraging density should be accompanied by specific policies which increase the energy efficiency of housing and promote the use of public transport.

Modifying the form and spatial structure of cities through urban planning can be an effective means to reduce greenhouse gas (GHG) emissions in cities. The supporters of the Compact City Approach to urban sustainability propose dense and centralized urban systems. In the case of population density, they argue that it promotes displacements of foot and public transport, and that typical apartments of compact fabrics require less energy than single-family dwellings. Therefore, high density should lead to low GHG emissions. During the last decade this association has been questioned because: a) there may be compensatory behaviors (more energy consumption and more GHG emissions in mobility and housing during weekends and holidays, and b) the fact of not considering the effects of the endogeneity associated with self-selection. In this paper, we analyze population density as a determinant of mobility and residential GHG emissions in Gran Concepción (Chile) using multivariate regression models. The results obtained indicate that density does not exert a significant impact on GHG emissions in mobility and housing. It is income differences that mostly explain individual GHG emissions variability. This calls into question the possible effectiveness of compactness policies in regional, cultural and climatic contexts different from those of the US and Europe and are excessively oriented towards the maintenance and increase of density in urban centers and slowing down the expansion of suburban neighborhoods.

Depuis le début du xx e siècle, et dans certains cas même avant, les grandes villes du monde connaissent un processus de décentralisation. Quoiqu'avec un certain décalage par rapport aux métropoles européennes et américaines, les capitales d'Amérique latine se décentralisent également, et la Zone Métropolitaine de la Vallée de Mexico (en abrégé Z mvm ) n'échappe pas à ce processus. Cet article examine l'impact d'une relocalisation de la population et de l'emploi sur la longueur des déplacements domicile-travail entre 2000 et 2010. La décentralisation de la population et de l'emploi a permis d'améliorer l'accessibilité des actifs à l'emploi total dans la région. Si la distance des lieux de résidence à l'emploi total s'est effectivement raccourcie, on devrait pouvoir observer une réduction des distances des déplacements pendulaires. Contrairement aux résultats d'autres études qui se sont intéressées à la Z mvm , nous avons constaté que l'accessibilité des actifs aux emplois s'est accrue, ce qui a eu pour effet une diminution des distances domicile-travail.

Since the beginning of the 20th century, and even before, world cities have been decentralizing. With some lag with respect to European and US metropolises, Latin-American capital cities are as well decentralizing. The Metropolitan Area of the Valley of Mexico (MAmv) is no exception. This research focuses on the possible effects of changes in the location of the population and employment on commuting distance between 2000 and 2010. Decentralization of the population and employment has improved workers' accessibility to total employment in the region. If the distance between population and total employment has shortened, this could lead to a reduction in commuting trip distances. Contrary to results obtained in other research applied to the MAmv, we find that workers' accessibility to total employment has shortened and that this has led to a decrease in commuting trip distances.

In this research we examine the relationship between the ecological footprint of commuting and several variables of urban form and spatial structure for the case of the Barcelona Metropolitan Region, paying special attention to the role of population density and polycentrism. Stopping the low density urban dispersion and encourage polycentrism are two of the main policies advocated by the supporters of the Compact City Approach to achieve more sustainable cities. The literature on the impact of population density offers inconclusive results and studies that address the role of spatial structure are very scarce. The results obtained in this research indicate that polycentrism has advantages in terms of low footprint. The effect of population density is more controversial. These results indicate that polycentric spatial planning can be a good strategy to reduce the ecological footprint of cities.

A considerable proportion of the greenhouse gases (GHG) emitted into the atmosphere is attributable to transport. In the case of large cities, GHG emissions associated with transport especially commuting mobility can be reduced by acting on the built environment. According to the Compact City-Approach to urban sustainability, the amount of energy per capita used to move within a city and therefore GHG emissions can be reduced by increasing the density and mix of residential and economic functions and directing the city's growth toward greater centralization, or concentrated (not dispersed) decentralization near the subcenters of employment and the economic activity corridors along the main routes of communication. We tested the predictions of the Compact City Approach regarding the influence of the built environment on GHG emissions associated with commuting mobility in the Metropolitan Zone of Mexico Valley (MZMV). Our results indicate that almost all the predictions are fulfilled. Therefore, urban land policies in line with the Compact City Approach that seek to reduce the amount of emissions are fully relevant.

One of the most controversial aspects of the debate on urban sustainability is to what extent the overall environmental impact of cities is determined by their shape and spatial structure. Compact City Approach defenders argue that people living in the densest and central areas of large cities have low environmental impact. Residential density and distance to the Central Business District (CBD) are the most common indicators proposed to capture urban spatial structure of cities. In this paper we estimate the carbon footprint of residential energy consumption, commuting and leisure purposes mobility from 475 surveys conducted in Concepcion Metropolitan Area (Chile). After controlling for potential endogeneity problems and taken into account the socioeconomic aspects that may affect the value of the carbon footprint, residential density does not exercise significant influence, so compactness policies could prove ineffective. The results rule out that this result is due to the existence of compensatory behaviors that lead to abnormally high mobility for leisure purposes in denser areas. Income is the main element explaining the observed variability in footprint values.

Hi ha una previsio de que per l'any 2030 el 60% de la poblacio mundial viura a les ciutats, sent les arees on mes energia es gasta i mes aliments es necessiten per abastir a la poblacio. Amb aquestes dades es de preveure que es plantegin i es busquin solucions als espais urbanitzats, i en particular, a com es podran alimentar a totes les persones que viuen en les ciutats. La idea principal d'aquest treball es analitzar la capacitat de dues tipologies de barris diferents de Barcelona, Sarria i Verdum-Prosperitat, per ser alimentariament autosuficient, fent una analisi interdisciplinaria, utilitzant eines socials, ambientals i geografiques. Diferents escenaris han sigut plantejats, centrats en el cultiu en exteriors i/o terrats i conreant nomes tomaquets o hortalisses. Els resultats mes destacables assolits son, que els principals promotors de l'agricultura urbana son els centres educatius, on una gran majoria d'escoles tenen hort escolar, el 60% a Verdum-Prosperitat i el 81% a Sarria. Per una altra banda, l'espai dedicat a l'agricultura urbana en els dos barries es insignificant, 0'5cm2/habitant a Verdum-Prosperitat i 25cm2/habitant a Sarria, pero, el potencial seria considerable, de 10m2/habitant i de 47m2/habitant respectivament. El barri de Sarria es podria autoabastir del multicultiu proposat dues vegades ell mateix (202%), i Verdum-Prosperitat arribaria a autoabastir a un 40% de la seva poblacio. Finalment, s'han establert una serie de propostes per ajudar a desenvolupar noves iniciatives als barris de Barcelona, per convertir les seves cobertes i part dels seus exteriors en zones verdes d'intercanvi veinal, d'autosuficiencia alimentaria i de captacio de CO2.

This article estimates the effect of polycentrism on population distribution in the Metropolitan Zone of the Mexico Valley (MZMV) between 1995 and 2010. According to NUE [New Urban Economics] polycentric models, the higher the distance to employment centers, the lower the population density. It was found that sub-centers have a positive effect on population density, despite the strong monocentric inertia in the metropolitan area. However, the results also show an increasing gap between employment and housing spaces. This gap makes it increasingly difficult to reduce commuting distances. On the other hand transportation infrastructure has a strong structuring capacity, and its effect on population density becomes stronger at the expense of the influence of employment sub-centers.

The compensation hypothesis poses the possibility that individuals who live in dense urban centres have a greater propensity to have a second residence and/or to travel more frequently to more distant destinations on the weekends and vacations than individuals who live in zones that are not so dense. Given this context, the net effect of density in environmental terms is not clear. In this study, we check the compensation hypothesis in the Barcelona Metropolitan Area using the ecological footprint of mobility and housing as global environmental impact indicator. The results strongly reject the compensation hypothesis, although they do detect the existence of a maximum level of density beyond which a positive impact is exerted. (C) 2013 Elsevier B.V. All rights reserved.

No existe una definicion comunmente aceptada de dispersion urbana (urban sprawl), de modo que la investigacion aplicada ha trabajado con diferentes indicadores que pretenden a su vez capturar los distintos significados con que se ha dotado al termino. En este trabajo se mide como ha evolucionado la dispersion de la poblacion y del empleo de la Region Metropolitana de Barcelona (RMB) entre 1986 y 2001. Las dimensiones exploradas se dividen en dos grupos: i) forma urbana (desconcentracion, baja densidad y discontinuidad) y ii) estructura urbana. A diferencia de algunos trabajos donde el policentrismo y el crecimiento lineal se presentan como dos formas de dispersion, en nuestro caso contraponemos la idea de expansion urbana estructurada (lineal o policentrica) con la de expansion urbana desestructurada (amorfa, caotica o aleatoria), equiparando esta ultima con la cuarta dimension de la dispersion. Los resultados obtenidos indican que la poblacion y el empleo de la RMB se han descentralizado de forma desconcentrada y la densidad residencial se ha reducido. Sin embargo, la RMB no ha crecido de forma discontinua ni desestructurada, sino todo lo contrario.

Latin American cities, like those from North America and Europe, experience problems of urban sprawl. However, few studies have dedicated exclusively to this phenomenon in specific cities, and this omission is particularly noticeable regarding cities not considered among the megalopolis of the continent. The present work analyzes urban sprawl through an urban form in the Concepción Metropolitan Area, Chile, between 1990 and 2009, considering local aspects that may have played a role in the process. The main empirical results obtained from this study reveal a metropolitan area that has expanded intensely over a 20-year period, growing from 9000 hectares to more than 17,000 ha for a 96% increment in the built-up area. The new urban surfaces consolidate a central conurbation that strengthens the role of the main downtowns, with less-intense occupation towards the sub-centers but in a structure that follows the transportation infrastructure. Over the last 20 years, the distance between the shapes has grown progressively by around 2 km, increasing the size of the ellipse by more than 1000 km2. In particular the complexity of the urbanized surfaces has grown, becoming more irregular in shape and less compact as they come to occupy larger areas. So our principal findings include: an increment of nearly 100% in the urban surface, the importance of a polycentric urban structure in the process of consolidation as a support for analyzing different spatial dynamics, and the growing morphological irregularity of the territory of the sprawl.