Étude d'un modèle simplifié pour l'analyse de cycle de vie des bâtiments

Co-encadrement de la thèse : Jacques CHEVALIEREnergy and environmental aspects are more and more integrated in the design process of buildings. Life Cycle Assessment (LCA) is generally used to assess the environmental performance of buildings. This method uses to date a high number of data which can be a limiting aspect for its application. For instance, it can be difficult for some manufacturers to give life cycle inventory (LCI) gathering several hundreds of flows. In addition, the interpretation of the results with about ten environmental indicators can be complex for the building practitioners. In this context, the aim of this research is to study a simplified model for the LCA of buildings. A simplified life cycle inventory (LCI) database gathering building materials, products and processes is first developed. It is composed of data from the Ecoinvent and INIES database with the help of a homogeneous nomenclature. The use of statistical methods then enables to assess the relevance of simplification of the LCA model. Simplified life cycle impact assessment (LCIA) model are built between the LCI flows and the LCIA indicators. They enable previously to the applications using the database to identify the flows that are the most significant in the environmental impact of a building. The understanding of the consequences of the simplification of the LCA model and the statistical methods used in this work enable to better appreciate the reliability of simplified LCA applied to building products and buildings as a whole.Les préoccupations énergétiques et environnementales sont de plus en plus au cœur du processus de conception des bâtiments. L'approche couramment retenue pour évaluer la performance environnementale d'un bâtiment est la méthode d'Analyse de Cycle de Vie (ACV). Cette méthode utilise, à ce jour, un nombre de données très important pouvant parfois être une limite pour son application. Par exemple, il est difficile pour certains fabricants de fournir des inventaires sous la forme de plusieurs centaines de flux. De même, l'interprétation des résultats à l'aide d'une dizaine d'indicateurs environnementaux peut paraître complexe pour les professionnels du bâtiment. Dans ce contexte, l'objectif de cette recherche est d'étudier un modèle simplifié pour l'ACV des bâtiments. Pour cela, une base de données simplifiée de flux d'inventaire de cycle de vie sur les matériaux, produits de construction et procédés est dans un premier temps développée. Elle est composée de données des bases Ecoinvent et INIES à l'aide d'une nomenclature homogénéisée. L'utilisation de méthodes statistiques permet ensuite de mettre en évidence les limites et potentialités de la simplification du modèle ACV. Des modèles simplifiés d'évaluation des impacts reliant les flux et les indicateurs de l'ACV sont notamment mis au point. Ils permettent préalablement aux applications utilisant la base de données, d'identifier les flux qui sont les plus déterminants dans l'impact environnemental d'un bâtiment. La compréhension des conséquences de la simplification du modèle et les méthodes statistiques utilisées dans ce travail permettent alors de mieux cerner la fiabilité des ACV simplifiées appliquées aux produits de construction et aux bâtiments

Towards the development of a simplified LCA-based model for buildings: recycling aspects

Disponible à l'adresse : http://leso.epfl.ch/files/content/sites/leso/files/download/publications/cisbat_proceedings_final_download.pdfInternational audienceThe building sector identified as a main contributor of energy and resources consumption contributes to many environmental impacts such as resources depletion or climate change. The identification, quantification and analysis of the main flows of matter, energy and pollution through the building system by means of appropriate methods can help to provide knowledge and tools for decision making. The Life Cycle Assessment (LCA) is, in this context, a method which can be applied to study the environmental impacts of buildings. Several LCA-based environmental analysis tools have been developed over the past few years. However, the relevance of such tools is often questioned. The methodological choices seriously influence the results of the analysis particularly in terms of data quality, type and number of environmental indicators, recycling take-account, modelling of the end of life (EOL) and more widely the chosen system boundaries. As a result of all of these shortcomings, the LCA studies are often seen as being too complex for application in the design process. In this article, we present the current LCA models characteristics for buildings. Then, we focus the analysis on the recycling and EOL of products by presenting the current practices. It has been found that current LCA models do account for material, recycling and end of life aspects but in a way so that it is not an easy task to evaluate the design choices for these aspects. Through the adopted methodology, main recycling criteria of LCA models were identified and consequences of defining a proper boundary system for a LCA model are discussed. We conclude by discussing the challenges of improving the LCA methodology for buildings

Energy saving potentials in historic buildings’ renovations ::to which extent is the heating demand limit value (SIA 380/1) reachable and at which costs?

The renovation of historic buildings is essential to meet the Swiss objectives for energy consumption in 2050. These buildings offer a great saving potential, however, the heritage preservation has to be considered in the renovation scenarios. While essential for the historic conservation, this consideration restricts the renovation possibilities to achieve the heating demand requirements according to the SIA 380/1 standard. This study introduces a framework for identifying the suitable historic buildings’ renovation schemes considering life cycle costs, energy and life cycle environmental impacts. With a case study, the feasibility of achieving the energy performance SIA 380/1 standard is then discussed

Adaptation of environmental data to national and sectorial context: application for reinforcing steel sold on the French market

Purpose: Environmental data for steel products are generally proposed at a continental or a global scale. The question we are tackling here is: does the fact that steel as a global market necessarily reduces the need for national data? Methods: In this study, the environmental impact of reinforcing steel sold in France is evaluated. To do so, a specific environmental inventory is adapted from Ecoinvent database. CML method is used for impact calculation and both methods "recycled content” as well as "end of life recycling approach” are tested. Results and discussion: This study shows that there is a specificity of reinforcing steel products sold in France compared to European value. It is due to the fact that reinforcing steel is mainly made with recycled steel as the market growth for construction product in France is limited allowing a very high recycled content. This result is not sensitive neither to the allocation method used for recycling (cut-off approach or system expansion) nor to transport distance and electricity country mix used. Conclusions: The result of this study can be used with confidence in every construction site work located on the French territory. Furthermore, the present study advocates for an adaptation of global database to local context defined by a specific industrial sector and a geographic region even for product such as steel that may be considered as a first approximation as a global produc

Methodology for cost-effective energy and carbon emissions optimization in building renovation (Annex 56)

"Energy in Buildings and Communities Programme, March 2017"Buildings are responsible for a major share of energy use and have been a special target in the global actions for climate change mitigation, with measures that aim at improving their energy efficiency, reduce carbon emissions and increase renewable energy use. The IEA-EBC Annex 56 project «Cost-Effective Energy and Carbon Emissions Optimization in Building Renovation» intends to develop the basics for future standards, which aim at maximizing effects on reducing carbon emissions and primary energy use while taking into account the cost-effectiveness of related measures. The IEA EBC Annex 56 project pays special attention to cost effective energy related renovation of existing residential buildings and low-tech office buildings (without air conditioning systems).info:eu-repo/semantics/publishedVersio

DE LA GESTION DES INCERTITUDES EN ANALYSE DE CYCLE DE VIE

International audienc

Assessing the operational energy profiles of UK educational buildings ::findings from detailed surveys and modelling compared to measured consumption

This paper presents the preliminary findings from the first stage of a physical survey and modelling Case Study conducted to obtain Modelled and Actual Energy Consumption Profiles for a UK multi-storey mixed use educational building. The purpose of the study is to provide an insight into how accurately current models and software can predict the actual energy consumption in such a building, with a view to informing the development of Operational and Asset Ratings for Buildings in the EU as part of the EPBD Article 7 requirements. The study also briefly discusses the potential problems inherent in the use of modelling techniques for assessing the energy performance of buildings. The data obtained through this study allowed predicted energy usage profiles to be compiled from the level of individual items of equipment through to the whole building. These data were subsequently analysed using standard spreadsheet and building energy simulation software. The results of the analysis enabled predicted energy consumption profiles for both heating/cooling and electrical energy use to be obtained, as well as a UK iSBEM asset-type compliance rating. The predicted profiles and compliance rating were then compared to the monitored actual energy consumption profiles obtained over the same period. The main conclusions were that, despite the time needed to undertake the physical survey, the level of detail of this study and survey were insufficient to predict the energy consumptions of the building with confidence. It was seen that the various approaches gave a reasonable estimate of the gas consumption using ECOTECT, and a reasonable estimate of the electrical consumption using iSBEM. However, overall it was felt that the models were too inaccurate to be used with any confidence. This results of this Case Study also support the view that for prediction of electrical consumption then statistical measures, such as benchmarks, are likely to enable more confident predictions of energy use by generic activity type

Calcul probabiliste de la performance énergétique des bâtiments

Le Laboratoire d'Energétique Solaire et de Physique du Bâtiment (LESBAT) de l'Institut de Génie Thermqiue (IGT) de la Haute École d'Ingénierie et de Gestion du Canton de Vaud (HEIG-VD) a développé une méthode de simulation énergétique probabiliste des bâtiments tenant compte de l'incertitude des valeurs standards des normes SIA (climat, performance réelle des équipements, température intérieure, etc.)