Anne-Françoise Marique

Toward Low Energy Cities

Summary Within the framework of sustainable development, it is important to take into account environmental aspects of urban areas related to their energy use. In this article a methodology is proposed for assessing residential energy uses for buildings and transport at the city scale. This method is based on the use of geographic information system (GIS) tools combined with a statistical treatment of urban and transport criteria. The methodology allows us to model building and transport energy use at the city scale, as well as to consider the possible evolution of city energy consumption and to simulate the effects of some strategies of urban renewal. An application is given to study different energy management strategies for the urban area of Li` ege, Belgium. Building and transport energy consumption are compared at the city scale and their possible evolution in the future is highlighted. Forecast scenarios

A method to evaluate the energy consumption of suburban neighborhoods

Energy use in buildings, transportation systems, and lighting networks represents a significant contribution to the overall energy consumption in urban and suburban areas. This article 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 taken 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.

Towards sustainable neighbourhoods: a new handbook and its application

This paper presents a practical handbook that aims at helping local authorities and private developers to build and assess “sustainable neighbourhoods” in Wallonia (Belgium). This handbook was developed by the Research Centre on Territorial, Urban and Rural Sciences (Lepur, University of Liege), at the request of the Walloon Minister of the Environment, Spatial Planning and Mobility. The concrete aim of the handbook is to concretely define the concept of “sustainable neighbourhood” by clearly tagging the minimum criteria that a real estate project must meet to obtain the “sustainable neighbourhood” label in Wallonia. It is a tool for decision support in the design as well as the evaluation of real estate projects, since the early stages of their design. The handbook is structured into 5 main themes and 25 criteria of sustainability. In a broad vision of sustainability, this handbook is not strictly limited to energy issues but considers “sustainability” in all its multiple components: location, network connection, mobility of inhabitants, use of natural resources, landscaping, waste management, diversity of function, social interactions, among others. The handbook is firstly presented and, then, applied to 12 recent case studies in order to identify common invariants in the design process of “sustainable neighbourhoods” and barriers to the integration of cross-cutting principles of sustainability in neighbourhood projects. Our main results namely show that the criteria dealing with energy performance of buildings and green spaces have percolated in many cases. However, the diversity of housing types, the accessibility to handicapped peoples, social diversity and participation issues remain poorly addressed in most of the cases studies.

Cradle-to-grave life-cycle assessment within the built environment: Comparison between the refurbishment and the complete reconstruction of an office building in Belgium

In the current context of the necessary sustainability transition of the built environment, it is widely recognized that buildings are a major contributor to the energy consumption of fossil fuels and the emission of CO2. Most of the debates, policies and research are however dedicated to the sole construction of new very efficient (up to zero-energy) building, neglecting the potential of actions on the existing building stock. In this context, we argue that LCA tools are of a huge interest to objectivise the need to refurbish old buildings, in order to increase their energy efficiency and extend their life span, and to compare this strategy to the demolition/reconstruction of buildings. To achieve this aim, this paper aims at updating an existing tool that enables to carry out the life cycle assessment of buildings, by taking into account demolition and construction phases. Then, the tool is applied to one case study of the low-energy refurbishment of a public office building in Brussels, to compare the impacts of the complete demolition followed by a complete reconstruction (rebuild project) to the retrofitting of the existing building (retrofit project). Our main findings confirm the huge impact of the use phase, highlight the impact (energy and CO2 emissions) of the construction and demolition phases and show that the in-depth renovation of this building leads to lower environmental indicators compared to its full reconstruction. The tool and results provided in this paper support the development of policies in favour of the retrofitting of the existing building stock and highlight the importance of including the whole life cycle of the building in the analysis.