The built environment is composed of buildings, infrastructures and cultural landscapes (stocks). These man-made artefacts constitute a complex capital (natural, man-made, human, social and cultural) and its evolution is a crucial parameter in sustainable development. Their composition and dynamics can be modelled as flows or as capitals or combinations of the two. Examples of the modelling of the long-term behaviour of different types of stock are given and their behaviour is analysed and discussed. A resource economic framework is presented and strategies for two different types of stocks, old/stationary and new/expanding, are compared. The importance of institutional regimes for the long-term management of stocks and the relation to demographic and retirement finance are discussed. The long-term institutional aspects have to be taken into account to avoid dramatic losses of economic, social and cultural capitals in the coming decades. L'environnement construit est composé de bâtiments, d'infrastructures et de paysages aménagés (parcs et jardins). Ces artéfacts fabriqués par l'homme constituent un capital complexe (naturel, façonné par l'homme, humain, social et culturel) et son évolution est un paramètre crucial du développement durable. Leur composition et leur dynamique peuvent être modélisées sous la forme de flux ou de capitaux ou d'une combinaison des deux. L'article donne des exemples de la modélisation du comportement à long terme de différents types de stocks de bâtiments puis analyse et examine leur comportement. Il présente un cadre d'analyse d'économie de ressource et compare des stratégies pour de deux types différents de stocks de bâtiments, à savoir un stock ancien/statique et un stock nouveau/en extension. L'article examine ensuite l'importance des régimes institutionnels pour la gestion à long terme de stocks de bâtiments ainsi que leurs rapports avec l'évolution démographique et les plans de financement de la retraite. Les aspects institutionnels dans le long terme doivent être pris en compte pour éviter les pertes dramatiques de capitaux économiques, sociaux et culturels dans les décennies à venir. Mots clés: gestion des actifs, stocks de bâtiments, remise en état, rénovation, économie de ressources, développement durable

During China's rapid urbanization and modernization process, the energy and mass flows as well as the related environmental impacts of the Chinese building and infrastructure stocks deserve attention due to the high volume of construction activity, the possibly short lifespan of the new constructions, and the increasing need for energy and construction materials, which have already led to severe environmental impacts. The objective of this study is to model the energy and material input and output through the construction and operation activities in the reference year (2005) to estimate future development during the ongoing urbanization process (until 2050) under present conditions (Trend scenario) and to formulate alternative scenarios with reduced resource consumption and environmental impacts. An integrated life cycle assessment (LCA) model is proposed by taking into account the material and energy flows and the related environmental impacts through a combined bottom-up and top-down approach. The historical evolution from 1978 to 2005 is analysed as a basis for the forecasting projections. The different age classes of the stock are modelled as cohorts classified by use and by type (urban/rural). The transitions of the key parameters follow a logistic function. The results show the possibilities and limitations of alternative long-term developments. The limitations of the model both in structure and input data are discussed. Alors que la Chine s'urbanise et se modernise rapidement, les flux d'énergie et de masse ainsi que les impacts correspondants sur l'environnement du patrimoine bâti et du stock d'infrastructures méritent notre attention pour les raisons suivantes: activité importante dans la construction, courte vie possible des constructions nouvelles et augmentation des besoins en énergie et matériaux de construction, qui ont déjà des conséquences graves sur l'environnement. L'objectif de cette étude est de modéliser les entrées et les sorties d'énergie et de matériaux liées aux activités et aux opérations de construction au cours de l'année de référence (2005) et d'estimer l'évolution durant l'urbanisation actuelle (jusqu'en 2050) dans les conditions actuelles (Scénario des tendances) et d'élaborer des scénarios alternatifs caractérisés par une réduction de la consommation des ressources et de l'impact environnemental. L'auteur propose un modèle d'évaluation intégrée du cycle de vie (LCA) qui tiendrait compte des flux de matériaux et d'énergie et de l'impact correspondant sur l'environnement dans le cadre d'une approche ascendante et descendante. Il étudie l'évolution historique de 1978 à 2005 comme base de projection de prévisions. Les différentes classes d'âge des stocks sont modélisés comme cohortes classées par usage et par type (urbain/rural). Les transitions des paramètres clés suivent une fonction logique. Les résultats indiquent les possibilités et les limites d'autres développements à long terme. Les limites du modèle tant en en ce qui concerne les structures que les données d'entrée sont examinées. Mots clès: patrimoine bâti, stock d'infrastructures, analyse du cycle de vie, consommation de ressources, durabilité, analyse des tendances, Chine

The integrated description of the building geometry and the element attributes of the building information model (BIM) can reduce the effort needed to acquire data for life cycle assessment (LCA) and life cycle costing (LCC) at each design stage while supporting their potential for analyzing life cycle performances and feeding back to the design process. To support this, several methods and tools have been proposed that aim to obtain the life cycle performances of buildings following the level of model fidelity with the life cycle inventory (LCI) database at different scales. However, inconsistencies in decision-making caused by regional differences in LCA/LCC data sources, benchmarks, and building standards cannot be ignored. In this study, a scalable LCA/LCC method integrated with the BIM platform is proposed for the whole green building design process in the Chinese context, and it is implemented with a developed tool based on Revit. A national-/regional-specified database of building elements and materials is established. Referring to China’s carbon-neutral target and relevant standards for green buildings, the baseline values are deduced, and a reference building is defined accordingly to facilitate the evaluation and improvement of the design scheme. According to the Assessment Standard for Green Building (GB50378-2019) and the survey of architectural design practices in China, the key parameters at different design stages are defined. The method and tool are demonstrated using the case study of a school building, analyzing its life cycle carbon emissions and life cycle costs throughout the design process. The results show that the proposed method can facilitate the improvement of the scheme at different design stages and that it can cope with different data accuracies and different LODs in the building information model in the Chinese green building design process. Lastly, the uncertainties raised by the data quality and time-associated factors are discussed.

The main considerations in the early stage of architectural design are usually related to form and function. At the same time, with the growing concern regarding energy saving and carbon emission reduction, the parameters for the construction and physical quality of buildings are receiving more attention at the conceptual and schematic design stages. Diverse design options can emerge with the large number of variables to be considered in these stages. Moreover, the combined efforts to reduce buildings’ life cycle environmental impacts and cost, as well as the non-linear and often tradeoff relationship between the two objectives, make finding optimal design solutions for buildings’ life cycle performance complicated. Previous studies have established workflows to optimize buildings’ life cycle energy consumption, GWP, and/or cost; however, architectural design diversity has not been sufficiently discussed at the same time. In this study, a parametric optimization design process is established, aiming at minimizing the building’s operational energy consumption, life cycle environmental impacts, and life cycle cost. The setting of variables, as well as the workflows of the optimization process, is discussed from the perspective of both life cycle performance and architectural design diversity. A small-scale exhibition hall in China’s cold climate zone is selected as a case study. To approach the best design process applicable to this case, the optimal solution sets from different workflows under different variable settings are compared. The results show that by setting geometric and material variables in different steps in the entire optimization process, the resulting solutions can be a balance of architectural design and performance. In this case study, optimizing all of the design variables in one-step turned out to provide the best balance between design diversity and life cycle performance in the early design stage.