Perspectives pour une transition durable des territoires périurbains.

peer reviewedL’article traite de la transition durable des territoires périurbains. Deux leviers d’action sont mobilisés à cette fin: (1) la forme urbaine et (2) la mobilité. Trois types de scénarios centrés sur une évolution du stock bâti existant sont modélisés et évalués (la rénovation énergétique, la densification et la démolition/reconstruction) de façon à répondre à deux questions : « comment intervenir dans les quartiers périurbains existants? » et « où intervenir? ». Ces simulations montrent que le renouvellement périurbain par densification des quartiers les mieux localisés permet de dépasser le clivage traditionnel entre les modèles de la « ville compacte » et de la « ville diffuse », en offrant de véritables opportunités pour la transition durable des territoires périurbains existants. Ces résultats théoriques, et appréhendés du seul point de vue énergétique, sont ensuite recadrés dans un contexte plus large pour mettre en évidence les opportunités, les limitations, les contraintes et la faisabilité de ces scénarios.SOlutions for Low Energy Neighbourhood

Retrofitting the suburbs: Insulation, density, urban form and location

The effects of urban sprawl have been well documented, particularly regarding energy consumption. Suburban neighbourhoods are known to be energy inefficient and urban sprawl is considered as a major issue for sustainable development. To improve the energy efficiency of existing suburban urban fabrics is a major challenge that must be addressed to favour a sustainability transition of our built environment. In this context, this paper aims at investigating several scenarios that could be developed to improve the sustainability of existing suburban neighbourhoods: three main types of scenarios (building insulation, density, and urban form) and twelve sub-scenarios, which are focused on the possible evolution of the existing suburban building stocks, are proposed. Quantitative methods developed in previous research are used to assess and compare building and transportation energy consumption of a representative suburban case study. This application aims at investigating two main research questions: (1) "how to intervene in suburban neighbourhoods?" and (2) «where to intervene?" The main results of this application, which are focused on energy efficiency, are then studied in a larger framework to highlight their opportunities and constraints. The main findings of the paper are that, beyond the traditional polarisation of the debates on the energy efficiency of our built environment between the “compact” and the “sprawled” city, a new pragmatic paradigm, which is focused on the smooth densification of existing suburban neighbourhoods, can make them evolve towards greater sustainability.Solutions for Low Energy Neighbourhood

Des quartiers durables en Wallonie. Etat d'avancement des travaux relatifs à l'évaluation des projets de quartiers durables.

Référentiel "quartiers durables

A method to evaluate the energy consumption of suburban neighbourhoods. Prospects for a sustainable suburban renewal in Wallonia.

The process of urban sprawl, which commonly describes physically expanding urban areas, is a major issue for sustainable development. Urban sprawl is known to represent a significant contribution to the overall energy consumption of a territory for energy needs in buildings and for transportation. In this context, the thesis focuses on the energy assessment of existing suburban neighborhoods. The assessment includes two parts: (1) a computational approach combining dynamic simulation tools and a database of building typologies to determine the energy consumed in heating and (2) an empirical approach to assess the energy consumed by transportation systems (home-to-work and home-to-school journeys). The links between the spatial structure of the territory and energy use for commuting are highlighted. Several renewal strategies are proposed to improve energy efficiency in existing suburban neighborhoods. There investigate the thermal retrofitting of existing neighborhoods, the built density and demolition/reconstruction processes together with the location of the neighborhoods. Urban structure acts upon travel energy consumption for commuting. A good mix between work, schools and dwellings at the local scale, which allows reduced travel distances, is a good strategy to reduce transport energy consumption, whereas means of transport used is only of little impact. Student travel behaviors are specific to the level of education and the type of neighborhood. Finally, the thesis discusses the practical implications of the research to operationalize a suburban renewal that articulates energy efficiency of buildings and neighborhoods but also energy efficiency of the urban structure.L’étalement urbain monofonctionnel et peu dense de la fonction résidentielle constitue un des phénomènes les plus marquants de l’évolution de nos territoires depuis la révolution industrielle. Selon un rapport de l’Agence Européenne pour l’Environnement (2006), l’étalement urbain menace, par sa rapidité et sa constance, l’équilibre environnemental, social et économique de l’Europe. La question énergétique, en particulier, est centrale et concerne directement ce modèle de développement, tant en termes de bâti que de mobilité car les territoires périurbains sont très dépendants de l'automobile. Partant des hypothèses que la crise énergétique est un élément déclencheur pour interroger la mutation des espaces périurbains vers un modèle plus durable et que les modèles de la ville compacte et de la ville diffuse ne peuvent répondre aux enjeux rencontrés, la thèse aborde la question du recyclage des quartiers périurbains existants, sous l'angle énergétique. Une instrumentation permettant de quantifier les consommations énergétiques relatives au chauffage des bâtiments et aux déplacements des personnes, à l’échelle des quartiers, est d’abord développée. Sur cette base, l’efficacité énergétique du modèle périurbain wallon et les conditions de sa mutation vers des quartiers périurbains plus durables sont investiguées. Deux leviers d’actions sont mobilisés dans le cadre de cette intervention : la forme urbaine et la mobilité. La forme urbaine, d’abord, est étudiée en complémentarité de l’échelle du bâtiment individuel car les mesures apportées à l’échelle du bâtiment (renforcement de l’isolation, recours à des énergies renouvelables, etc.) ne sont pas en mesure de répondre, seules, à l’ampleur des enjeux énergétiques qui touchent les territoires périurbains. La mobilité, ensuite, car l’étalement urbain est entretenu et favorisé, en grande partie, par la capacité des ménages à se déplacer individuellement, rapidement et sur de grandes distances. A cet effet, deux indicateurs principaux sont développés et discutés : les besoins de chauffage de différents types de formes périurbaines et un indice de performance des déplacements qui prend en compte distance parcourue, fréquence et mode de transport. Des variations paramétriques sont réalisées sur des quartiers représentatifs pour déterminer les paramètres les plus influents. Sur cette base, des scénarios de renouvellement des quartiers périurbains sont proposés et leur impact énergétique potentiel quantifié. Ces scénarios abordent la rénovation énergétique des quartiers, la densification et la démolition / reconstruction. Ils montrent, qu’outre l’efficacité énergétique des bâtiments, les caractéristiques relatives à la forme urbaine ont un impact significatif sur les consommations. L’impact de la structure territoriale (définie comme la conjonction de la localisation spatiale des emplois, des commerces, etc., la distribution spatiale de la population selon son lieu de résidence et les infrastructures) sur les consommations d’énergie relatives aux déplacements des personnes est enfin investiguée sur l’ensemble du territoire régional, en abordant l’influence de la localisation résidentielle sur les déplacements domicile-travail et sur les déplacements scolaires. La génération de mobilité est fortement liée à la localisation spatiale des lieux émetteurs et récepteurs de flux (résidences, emplois, écoles). Une approche locale permet d’identifier, hors des agglomérations principales, des noyaux secondaires qui présentent également des consommations faibles pour les déplacements. La mixité fonctionnelle en particulier permet, mieux que la densité de logements, d’expliquer la variation des consommations d’énergie pour les déplacements. La distance parcourue a un impact considérable sur les consommations d’énergie pour les déplacements alors que le mode de transport utilisé n’a qu’une influence relativement faible. Les comportements de mobilité pour les déplacements scolaires présentent des spécificités propres selon le niveau de scolarité considéré mais restent nettement moins consommateurs que les déplacements domicile-travail. La thèse se conclut par la discussion des incidences pratiques de la recherche pour l’opérationnalisation d’un renouvellement périurbain qui s’articule autour de l’efficacité énergétique des bâtiments et des quartiers et de l’efficacité énergétique de l’urbanisation. L’aménagement du territoire doit créer des conditions favorables pour orienter les activités et les investissements au bon endroit et pour favoriser des formes urbaines plus efficaces

Development of an urban typology to assess residential environmental performance at the city scale

peer reviewedIn this research, a typology of urban blocks is drawn up for the urban area of Liege. This typology of urban blocks is organized into a set of themes according to various environmental parameters. This paper presents the energy part of this typology on the residential building stock of Liege, which includes four topics: residential buildings energy consumption; transport energy consumption of residents; development potentialities of public transport and development potentialities of energy networks. The proposed typology was elaborated through the use of GIS tools combined with a statistical treatment of several specific criteria at the urban block scale. For each class of this typology, a representative block is selected for further energy simulations in order to model residential energy use related to buildings, transport and energy networks at the city scale. The methodology developed in this paper is adapted to urban, suburban and rural zones. It can thus be adapted and/or reproduced on many other territories in Belgium but also in Europe or even further

Urban Sprawl and Travel Energy Consumption: the Case of the Walloon Region of Belgium

peer reviewedIn the actual context of growing interests in environmental issues, reducing energy consumption in the transport sector, which represents 27% of final energy in the Walloon region of Belgium, appears as an important policy target. Although it is often argued that more compact urban forms would significantly reduce transport energy consumption, urban sprawl is a concern in a large part of the regional territory. Moreover, assessment tools dedicated to transport energy consumption are lacking. In this context, the paper first presents a quantitative method developed to assess the transport system in the Walloon region of Belgium. Statistical data available at the neighbourhood scale and characteristics of cars and public vehicles are used to predict transport needs and assess energy consumption as far as home-to-work and home-to-school travels are concerned. Three index are presented and mapped (the energy performance index, the modal share and the mean distance travelled) to investigate the interdependences between spatial planning, urban sprawl and travel energy consumption in the Walloon region of Belgium. Three complementary scales are used: the “municipality” scale allows to highlight the general structure of the territory whereas the “former municipality” and the “census block” scales (the smallest geographical unit in which data are available in Belgium) highlight more detailed phenomenon. The evolution of the performance index between 1991 and 2001 and the difference in energy performance between home-to-work and home-to-school travels are also presented. Our main findings are presented and highlight that urban planning acts upon travel energy consumption. We show particularly that main cities present low energy consumption. However, a local scale approach is useful to highlight the existence of secondary suburban and rural cores presenting low transport energy consumption. In this respect, distance from home to destination is paramount while the mode of transport used has a lower impact.Suburban Areas Favoring Energy efficiency (SAFE

Les projets SUN et SOLEN : Soutenir la régénération durable des quartiers.

SUN (Sustainable Urban Neighbourhoods) et SOLEN (SOlutions for Low Energy Neighbourhoods

A method for evaluating transport energy consumption in suburban areas

peer reviewedUrban sprawl is a major issue for sustainable development. It represents a significant contribution to energy consumption of a territory especially due to transportation requirements. However, transport energy consumption is rarely taken into account when the sustainability of suburban structures is studied. In this context, the paper presents a method to estimate transport energy consumption in residential suburban areas. The study aimed, on this basis, at highlighting the most efficient strategies needed to promote awareness and to give practical hints on how to reduce transport energy consumption linked to urban sprawl in existing and future suburban neighborhoods. The method uses data collected by using empirical surveys and GIS. An application of this method is presented concerning the comparison of four suburban districts located in Belgium to demonstrate the advantages of the approach. The influence of several parameters, such as distance to work places and services, use of public transport and performance of the vehicles, are then discussed to allow a range of different development situations to be explored. The results of the case studies highlight that travelled distances, and thus a good mix between activities at the living area scale, are of primordial importance for the energy performance, whereas means of transport used is only of little impact. Improving the performance of the vehicles and favoring home-work give also significant energy savings. The method can be used when planning new areas or retrofitting existing ones, as well as promoting more sustainable life styles regarding transport habits.SAFE (Suburban Areas Favoring Energy efficiency

A method to assess global energy requirements of suburban areas at the neighbourhood scale

peer reviewedThis article presents the method developed to assess existing suburban neighbourhoods in order to improve their energy efficiency. It combines the use of dynamic simulation tools to evaluate energy requirements for heating and lighting residential buildings, a statistical approach to assess the transport system and a simplified calculation to take also into account public lighting. The method is completed by a life-cycle analysis of buildings. An application is presented concerning the comparison of three typical suburban structures in the Walloon region of Belgium. The influence of parameters which are often underestimated, like distribution of buildings or location, on the global energy performances of suburban fabrics is tested. The results of this exercise are presented and its limits are discussed.Suburban Areas Favoring Energy efficienc

A Method to Evaluate the Energy Consumption of Suburban Neighbourhoods

Energy use in buildings, transportation systems and lighting networks represents a significant contribution to the overall energy consumption in urban and suburban areas. This paper presents a method to evaluate the energy consumption of suburban neighborhoods from these three points of view, aiming to highlight the most relevant variables linking urban form and neighborhoods energy consumptions. The method includes three parts: 1) a computational approach combining dynamic simulation tools and a database of building typologies to determine the energy consumed in heating; 2) an empirical approach to assess the energy consumed by transportation systems (four purposes of travel are taking into account: work, school, leisure and shopping); and 3) a simplified approach to calculate the energy consumed by public lighting. Results from the application of the method to three characteristic suburban neighborhoods in Belgium are presented along with a life cycle energy assessment of buildings. A sensitivity analysis was conducted to determine the effects of building and neighborhood characteristics and of building inhabitant behavior on calculated energy consumption. Results from the analysis show that building insulation, building distribution, heating system management and neighborhood location are critically important factors in the energy efficiency of suburban residential areas.Suburban Areas Favoring Energy efficiency (SAFE