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International audience; Performance optimization has become a standard approach for the design and control of energy systems. The building sector doesn't escape this trend with very dynamic research activity on the subject. This allows designing more and more efficient buildings that contributes to limit the climate change's effects. Design of buildings is usually based on a sequential approach: reduction of demand improvement of energy efficiency and finally use of renewable energies. A holistic building design approach is more efficient since the optimum of a system can be different from the one obtained by separating its components. It is thus necessary to optimize the design by considering the building as a whole (envelope, system, occupants, and environment) and over its lifetime, particularly in the perspective of the climate change. In this context, there are significant difficulties linked to calculation time, dynamic simulations of the building (envelope and systems), taking into account the climate change, combinatorial explosion related to the decision parameters during the optimization, and inclusion of uncertainties ... It is therefore necessary to use specific methodologies such as the use of surrogate models or parallel computing. The optimization is obviously multi-criteria and the overall optimum must be obtained with a reasonable computing time for an engineering office for example. The performance functions (environment, financial, comfort, reliability ...) can be evaluated with different tools that must be interoperable. In this context, we present a methodology and an environment for the holistic optimization of buildings. This environment allows the interoperability of numerical tools used by engineering offices. Finally, two optimized multi-criteria design case studies (2 test functions and the real building "Les Roches Blanche" in Chambéry) are presented to illustrate the approach and the developed environment.

International audience; Cities contribute to a large extent to anthropogenic environmental impacts, and their population is growing. Sustainability requires to provide suitable spaces for dwelling and working, while preserving resources, human health, biodiversity and climate. In this context, the aim of our work is to better understand the systemic links between decisions made by urban designers and consequences like emissions of pollutants and related impacts. Urban developments are complex systems including many interacting elements: buildings, outside spaces, networks, and occupants. Temporal and spatial transfer of pollution should be avoided, as well as replacing some impacts by others (e.g. emitting less greenhouse gases but increasing health problems). Such complex issues are generally addressed using qualitative approaches. But the importance of risks would justify more efforts towards a more rational decision making process. The objective is then to develop tools helping such a process.

International audience; Designing plus energy buildings, at lower environmental impact and lower cost, is a complex optimisation problem. In this context, this paper presents an ecodesign approach of a plus-energy house assisted by multicriteria optimisation. Illustrated by a real case, this approach uses a genetic algorithm to find a set of solutions as close as possible to the theoretical Pareto front, corresponding to the best compromises for the formulated problem. The solutions’ performance was evaluated using a dynamic building energy model (COMFIE), a life cycle analysis model (novaEQUER), and a construction cost database. In order to study the solutions’ robustness, the diversity of occupants’ behaviour was stochastically modelled. The proposed approach is thus contributing to the decision making process, beyond simple evaluation by simulation.

International audience; Environmental performance considerations in the construction sector extend from buildings to neighbourhoods, cities and territory. This transition implies a Life Cycle Assessment (LCA) adaptation to efficiently treat such complex systems. Indeed, performing environmental performance evaluations has already been done over the past few years but the existing LCA tools have to be improved regarding their userfriendliness to allow everyday urban planning stakeholders to use them. Providing keys to help the practice is a main subject to spread the large scale LCA evaluation and ensure a better urban planning trending to sustainable solutions. This objective is also motivated by local, national and European policies, particularly within the context of Paris COP21. The aim of this study is to explore enhancement perspectives to facilitate LCA scaling up from building to territory. This work is based on observations from case studies underlining operational issues due to the evaluation time consumption. The urban planning process is analysed to focus, at different stages, on operational responses that could be proposed considering objectives, stakeholders’ needs and potential drivers. In particular, for early stage decision making, an approach introducing urban typo-morphologies has been adopted to facilitate the comparison of large scale evaluations and scenarios. Such typo-morphologies, representing elemental bricks at building or block scale to build neighbourhoods or larger, have been widely described in the past. However, this work concentrates on the applicability of the approach to integrate this sort of description for environmental evaluation based on a multicomponent (buildings, energy, water, public spaces, transportation) description of the systems. Particularly, a focus has to be given to scaling up mechanism. Expert systems sets on heuristic rules could help exploiting a typo-morphologies database. This solution should ease the practice of urban environmental assessments.

International audience; Sustainability is now targeted in nearly all urban projects, but life cycle assessment (LCA) is generally seen as too complex, so that more qualitative approaches are preferred. Indeed, the importance of environmental problems regarding e.g. climate change, human health, biodiversity and resource depletion justifies a more precise decision making process. A life cycle simulation tool has been developed to model urban projects including various buildings, streets, green and other public spaces, and networks (drinking water, waste water, district heating...). This tool, developed in an object oriented approach, associates dynamic building energy simulation and LCA, complemented with modules for open spaces and networks. A set of environmental indicators is evaluated, e.g. resource depletion, energy and water consumption, global warming, waste generation, toxicity. Several alternatives can be compared, constituting an urban design aid. Continuous improvement of the tool has been performed since the 90’s, expanding the boundaries from buildings to districts assessment. A dynamic model was recently introduced to take into account temporal variation of the electricity consumption in buildings and interaction with the electricity system. Results show the importance of this dynamic evaluation in the case of plus-energy buildings. This multidisciplinary approach allows comprehensive assessment of districts, constituting a decision support in early phases of urban projects. The assessment of a project in the Greater Paris Area is presented to illustrate this integrated approach.

International audience; Designing plus energy buildings, at lower environmental impact and lower cost, is a complex optimisation problem. In this context, this communication presents an ecodesign approach assisted by multicriteria optimisation of plus-energy house. Illustrated by a real case, this approach uses a genetic algorithm to reach as much as possible the theoretical Pareto front, including solutions corresponding to the best compromise for the formulated problem. The solutions’ performance is evaluated using a dynamic thermal simulation model (COMFIE), a life cycle analysis mode (novaEQUER), and a cost database. A stochastic model was used to generate average occupancy scenarios in more realistic way than conventional approaches. The proposed approach is thus contributing to an aid in decision making, beyond simple evaluation by simulation.; Concevoir des bâtiments à énergie positive, à moindre impact environnemental et à moindre coût, constitue un problème d’optimisation complexe. Dans ce contexte, cette communication présente une démarche d’éco-conception de maisons à énergie positive assistée par optimisation multicritère. Illustrée sur un cas réel, cette démarche utilise un algorithme génétique pour approcher le plus efficacement possible le front de Pareto théorique, i.e. l’ensemble des solutions présentant les meilleurs compromis du problème formulé. La performance des solutions est évaluée par un modèle de simulation thermique dynamique (COMFIE), un modèle d’analyse de cycle de vie (novaEQUER) et des données de coûts de construction. Un modèle stochastique de comportement des occupants a permis de générer des scénarios moyens plus réalistes que les approches conventionnelles. La démarche proposée contribue ainsi à une aide à la décision, au-delà d’une simple évaluation par simulation.

International audience; La garantie de performance énergétique (GPE) est un levier essentiel pour le financement des bâtiments performants. L’objectif de ce travail est d’élaborer un processus fiable pour la GPE en définissant un objectif de performance intégrant des sources d’incertitudes ainsi que des possibilités d’ajustement sur des grandeurs relatives à l’occupation et au climat. La méthodologie suivie se divise en quatre étapes. Avant les travaux, les paramètres du modèle considérés a priori comme incertains sont caractérisés par une plage d’incertitude. Dans l’objectif d’identifier les paramètres les plus influents sur la consommation énergétique, une analyse de sensibilité est ensuite effectuée. Une loi de probabilité a priori est alors définie pour ces paramètres influents et une propagation des incertitudes et variabilités est réalisée permettant de définir un modèle d’ajustement et un seuil a priori de consommation dans une situation de référence. Après les travaux, la consommation réelle mesurée est ajustée pour tenir compte du climat et du comportement réel des occupants et peut être comparée à la valeur garantie.

International audience; Les outils d’analyse de cycle de vie (ACV) des bâtiments sont utilisés pour orienter la conception vers des ensembles bâtis plus durables. Ils doivent donc être des outils d’aide à la décision robustes. Or, les praticiens d’ACV sont confrontés à de nombreux choix (méthodes, scénarios, paramètres…) induisant des incertitudes dans les sorties du modèle et potentiellement une remise en question des résultats. Dans ce cadre, l’influence des paramètres incertains doit être mieux connue. Trois types d’analyses de sensibilité (le criblage de Morris et les analyses de sensibilité locale et globale), offrant différents compromis coût calculatoire - précision, ont permis d’identifier les paramètres les plus influents pour une maison individuelle performante. Ces travaux, menés avec l’outil d’ACV novaEQUER ont souligné l’influence de la durée de vie du bâtiment, du mix de production d’électricité et des contributeurs majeurs de l’efficacité énergétique de l’enveloppe. Une meilleure compréhension de l’effet des paramètres influents contribue à réduire l’incertitude et à fiabiliser les résultats d’ACV des bâtiments.

International audience; L’analyse du cycle de vie (ACV) est une méthode de plus en plus utilisée dans le secteur du bâtiment, en particulier pour l’aide à la conception Les études d’ACV sont classées en deux grandes familles : l’approche attributionnelle (ACV-A) et l’approche conséquentielle (ACV-C). Les études ACV-A allouent une responsabilité environnementale au cycle de vie du produit étudié (e.g. l’impact d’un bâtiment). L’ACV-C se focalise sur les conséquences environnementales d’une décision (e.g. décision de construire un nouveau bâtiment). Ceci influence la réalisation de l’étude, notamment au niveau des données utilisées et des techniques d’allocations employées (allocation ou extension du système). Cette communication propose une comparaison entre ACV-A et ACV-C sur un cas d’étude simple : une maison individuelle passive située près de Chambéry. Les différences entre les deux approches sont importantes et peuvent affecter le classement des variantes de conception. Les deux approches sont discutées en fonction de leur apport concernant un objectif d’éco-conception.

International audience; In France, 40 % of buildings are heated with electrical devices causing high peak load in winter. In this context, optimal strategies (under constraints related to comfort and maximum heating power) have been developed using the dynamic programming method in order to shift electricity consumption used for heating, taking advantage of the building thermal mass. However, this exact optimisation method is computationally intensive and can hardly be applied to real-time control. Complementary statistical techniques exist that allow for the extraction of logistic decision models from the optimal control simulation results. These rule extraction techniques model the relationship between explanatory variables and a response variable. In this study, a generalised linear model was used because it is able to mimic the general characteristics of the dynamic programming results with good precision and greatly reduced computational effort (150 times faster than the dynamic programming method).

International audience; A life cycle approach (LCA) is now commonly used for the environmental assessment of buildings. However, different methodological rules are currently found in the literature to estimate the energy and LCA balance for the use stage e.g. from an annual assessment to a one hour time step assessment. Another critical issue is related to the assessment of new low energy buildings equipped with on-site renewable energies. In this study, first, the consequences of using different Life Cycle Inventory (LCI) calculations for the electricity mix are analysed. Then, the consequences of using different allocation rules for the on-site renewable energy produced by PV panels are assessed. The results on a single individual house showed that the use phase results are very sensitive to the allocation rules. Regarding the temporal aspects, this study highlights the differences between dynamic and static approaches for both energy and LCA calculations. Finally, recommendations are given to improve the reliability of building LCA tools.

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International audience; Existing Building LCA tools are based upon a static method, considering yearly average processes and impacts. This paper presents a dynamic method that has been developed to evaluate electricity-related impacts in buildings. Results on case studies show important discrepancy between the static and dynamic methods. This study is a first step towards the introduction of consequential LCA parameters in life-cycle assessment of buildings.

International audience; In some Product Category Rules (PCR) defined to produce EDP according to ISO 14025, templates for reporting a reduced list of LCI flows can be provided e.g. ET Env. Declaration (Finland), INIES (France) etc.In the French EPD (called FDES), this template, not compulsory but hughly followed by the building industry, is included in the publicly EPD report available onlineObjective of the study : Assess the relevance of such reduced list of LCI flows in a French LCI database using industry data

International audience

International audience; The present paper gives an overview of a French national project on building performance. Named COMEPOS, started in 2013, it focuses on « Positive Energy » detached houses. It consists in the design, construction, operation and evaluation of 20 inhabited and innovative houses. This collaborative project includes constructors, industrial and academic partners, the latter involved both in the monitoring and the use of building performance simulation at different stages of the building's life. The paper offers an overview of how simulation technics can be used, in coordination with measurements, concerning points like the optimization of the design, performance evaluation, fault detection, but also improving simulation of real-life situations, for example by improving the knowledge about the impact of occupants' behaviour.

The IEA EBC Annex 72 focuses on the assessment of the primary energy demand, greenhouse gas emissions and environmental impacts of buildings during production, construction, use (including repair and replacement) and end of life (dismantling), i.e. during the entire life cycle of buildings. In one of its activities, reference buildings (size, materialisation, operational energy demand, etc.) were defined on which the existing national assessment methods are applied using national (if available) databases and (national/regional) approaches. The "be2226" office building in Lustenau, Austria was selected as one of the reference buildings. TU Graz established a BIM model and quantified the amount of building elements as well as construction materials required and the operational energy demand. The building assessment was carried out using the same material and energy demand but applying the LCA approach used in the different countries represented by the participating Annex experts. The results of these assessments are compared in view of identifying major discrepancies. Preliminary findings show that the greenhouse gas emissions per kg of building material differ up to a factor of two and more. Major differences in the building assessments are observed in the transports to the construction site (imports) and the construction activities as well as in the greenhouse gas emissions of the operational energy demand (electricity). The experts document their practical difficulties and how they overcame them. The results of this activity are used to better target harmonisation efforts.

Introduction: The international research project IEA EBC Annex 72 investigates the life cycle related environmental impacts caused by buildings. The project aims inter alia to harmonise LCA approaches on buildings. Methods: To identify major commonalities and discrepancies among national LCA approaches, reference buildings were defined to present and compare the national approaches. A residential high-rise building located in Tianjin, China, was selected as one of the reference buildings. The main construction elements are reinforced concrete shear walls, beams and floor slabs. The building has an energy reference area of 4566 m$^{2}$ and an operational heating energy demand of 250 MJ/m$^{2}$a. An expert team provided information on the quantities of building materials and elements required for the construction, established a BIM model and quantified the operational energy demand. Results: The greenhouse gas emissions and environmental impacts of the building were quantified using 17 country-specific national assessment methods and LCA databases. Comparisons of the results are shown on the level of building elements as well as the complete life cycle of the building. Conclusions: The results of these assessments show that the main differences lie in the LCA background data used, the scope of the assessment and the reference study period applied. Despite the variability in the greenhouse gas emissions determined with the 17 national methods, the individual results are relevant in the respective national context of the method, data, tool and benchmark used. It is important that environmental benchmarks correspond to the particular LCA approach and database of a country in which the benchmark is applied. Furthermore, the results imply to include building technologies as their contribution to the overall environmental impacts is not negligible. Grant support: The authors thank the IEA for its organizational support and the funding organizations in the participating countries for their financial support.

International audience; This chapter describes the research experience of the International Energy Agency-Energy in Buildings and Communities Programme Annex 72 members on the application of multi-objective optimization processes for the selection of design or retrofit actions that allow for improving different aspects (energy, environmental, economic, etc.) of buildings in a life cycle perspective. Thirteen case studies were examined focussing on methodologies, applications and results and deriving generic conclusions and guidelines for building designers and decision-makers.

Introduction: The international research project IEA EBC Annex 72 investigates the life cycle related environmental impacts caused by buildings. The project aims inter alia to harmonise LCA approaches on buildings. Methods: To identify major commonalities and discrepancies among national LCA approaches, reference buildings were defined to present and compare the national approaches. A residential high-rise building located in Tianjin, China, was selected as one of the reference buildings. The main construction elements are reinforced concrete shear walls, beams and floor slabs. The building has an energy reference area of 4566 m2 and an operational heating energy demand of 250 MJ/m2a. An expert team provided information on the quantities of building materials and elements required for the construction, established a BIM model and quantified the operational energy demand. Results: The greenhouse gas emissions and environmental impacts of the building were quantified using 17 country-specific national assessment methods and LCA databases. Comparisons of the results are shown on the level of building elements as well as the complete life cycle of the building. Conclusions: The results of these assessments show that the main differences lie in the LCA background data used, the scope of the assessment and the reference study period applied. Despite the variability in the greenhouse gas emissions determined with the 17 national methods, the individual results are relevant in the respective national context of the method, data, tool and benchmark used. It is important that environmental benchmarks correspond to the particular LCA approach and database of a country in which the benchmark is applied. Furthermore, the results imply to include building technologies as their contribution to the overall environmental impacts is not negligible. Grant support: The authors thank the IEA for its organizational support and the funding organizations in the participating countries for their financial support., IEA -International Energy Agency(undefined)

The IEA EBC Annex 72 focuses on the assessment of the primary energy demand, greenhouse gas emissions and environmental impacts of buildings during production, construction, use (including repair and replacement) and end of life (dismantling), i.e. during the entire life cycle of buildings. In one of its activities, reference buildings (size, materialisation, operational energy demand, etc.) were defined on which the existing national assessment methods are applied using national (if available) databases and (national/regional) approaches. The ?be2226? office building in Lustenau, Austria was selected as one of the reference buildings. TU Graz established a BIM model and quantified the amount of building elements as well as construction materials required and the operational energy demand. The building assessment was carried out using the same material and energy demand but applying the LCA approach used in the different countries represented by the participating Annex experts. The results of these assessments are compared in view of identifying major discrepancies. Preliminary findings show that the greenhouse gas emissions per kg of building material differ up to a factor of two and more. Major differences in the building assessments are observed in the transports to the construction site (imports) and the construction activities as well as in the greenhouse gas emissions of the operational energy demand (electricity). The experts document their practical difficulties and how they overcame them. The results of this activity are used to better target harmonisation efforts., IEA -International Association for the Evaluation of Educational Achievement(Slovenia)