Capital project planning for a circular economy

Achieving true sustainability in the conceptualization of new building projects requires radical change compared to traditional green-field projects; circular building principles in a circular economy must become a fundamental part of the process. These principles include product recovery management, life cycle assessment (LCA), design for disassembly sequence planning, adaptability, deconstruction, closed materials loops and dematerialization. These principles recognize the importance of the End-of-Life stage in existing buildings, including adaptive reuse as an attractive alternative in a circular economy. However, the early phases of capital project delivery lack well-developed methods to: (1) decide amongst green-field construction versus adaptive reuse, (2) pre-project planning for closed-loop cycle construction and (3) plan for the optimization of the benefits of adaptive reuse. In this article, we argue that the early capital projects delivery phases for a circular economy should have distinct stages, decision gates and more appropriate planning methods, such as selective disassembly, LCA monetization protocols and optimization methods. An investigation of related studies underpins the capital project planning framework proposed and the research that must still be accomplished to enable a more circular economy in the capital projects sector.     

Sustainability in the construction industry: A review of recent developments based on LCA

This review brings together research on life cycle assessment (LCA) applied within the building sector. More than ever, the construction industry is concerned with improving the social, economic and environmental indicators of sustainability. By applying LCA it is possible to optimise these aspects, from the extraction of raw materials to the final disposal of waste building materials. Firstly, this review details LCA concepts and focuses on the LCA methodology and tools employed in the built environment. Secondly, this paper outlines and discusses the differences between the LCA of building materials and components combinations versus the LCA of the full building life cycle. Finally, this work can be used by stakeholders as an important reference on LCA including up to date literature on approaches and methodologies to preserve the environment and therefore achieve sustainable development in both developed and developing countries.The present review has tried to compile and reflect the key milestones accomplished in LCA over the last 7 years, from 2000 to 2007 within the building sector. In summary, it can be stated that the application of LCA is fundamental to sustainability and improvement in building and construction. For industrial activities, SMEs must understand the application of LCA, not only to meet consumer demands for environmentally friendly products, but also to increase the productivity and competitiveness of the green construction markets. For this reason, this review looks at LCA because of its broad international acceptance as a means to improve environmental processes and services, and also for creating goals to prevent adverse environmental impacts, consequently enhancing quality of life and allowing people to live in a healthy environment.     

生命周期评价理论及在建筑领域中的应用综述

生命周期评价通过对建筑产品从原材料挖掘到报废拆除整个生命期的分析,为全面衡量建筑的可持续能力提供了工具。在介绍生命周期评价概念和理论框架的基础上,对生命周期评价三种主要模型（过程生命周期评价模型、投入-产出生命周期评价模型、混合生命周期评价模型）的内容与特点进行了总结。针对目前国内外研究现状,回顾了生命周期评价在建筑材料与部品和整体建筑产品的应用,对生命周期评价在建筑领域中的发展给予展望。研究深入了当前对于生命期评价理论的认识与了解,指明了全生命周期评价模型在建筑可持续能力评估方面的优点与不足,推动了全生命周期评价理论在我国的丰富与发展     

Ganzheitliche Analyse von Stahl‐ und Verbundeisenbahnbrücken

Holistic analysis on steel‐ and composite railway bridges – Innovative solutions for strengthening durability and reducing construction times (Part 1). Investigations on sustainability on infrastructure projects differ from comparable investigations on building constructions through their longer life‐cycle of the objects. Questions regarding sustainability are thus accompanied by questions of durability and simple, mostly undisturbed maintenance through the whole life‐cycle. By the application of innovative railway bridges with steel and composite constructions blocking times induced by the construction time and maintenance actions within the usage phase, can be effectively reduced. Additionally the optimization of restrictive fatigue‐details can affect the whole life‐cycle of a bridge‐construction. In the frame of the FOSTA‐AiF‐research project „Holistic Assessment of steel‐ and composite railway bridges according to criteria of sustainability“ different innovative railway bridge types have been compared to their corresponding conventional bridge types and evaluated over their whole life‐cycle to quantify their advantageousness. While this article shows the investigated innovative bridge‐variants in constructive regards and optimization proposals and design approaches are explained, the second article is about the holistic approach and the results of the sustainability assessment of the investigated steel‐and composite railway bridge.     

Integrating building information modelling with sustainability to design building projects at the conceptual stage

Lately the construction industry has become more interested in designing and constructing environmentally friendly buildings (e.g. sustainable buildings) that can provide both high performance and monetary savings. In general, sustainability integrates the following three related components: (1) environmental, (2) economic, (3) social well-being. Incorporating these components at the conceptual stage is achieved by using sustainable design, through which designers must identify associated materials and systems based on any selected certification (rating) system. The use of building information modelling (BIM) concepts helps engineers design digital models that allow owners to visualize the building before the physical implementation takes place. To apply BIM concepts, designers use tools to create 3D models of buildings where the design materials and systems are selected from the built-in database of these tools. Designers will not be able to quantify the environmental impacts of these materials to support the decisions needed to design sustainable buildings due to the following reasons: (1) a lack of information about the sustainable materials that are stored in the database, (2) a lack of interoperability between the design and analysis tools that enable full life cycle assessments (LCAs) of buildings. This paper presents a methodology that integrates BIM and LCA tools with a database for designing sustainable building projects. The methodology describes the development and implementation of a model that incorporates a database in which information about sustainable materials is stored and linked to a BIM (3D) module along with an LCA module and a certification and cost module. The goal of this model is to simplify the process of creating sustainable designs and to evaluate the environmental impacts (EI) of newly designed buildings at the conceptual stage of their life. An actual building project is presented in order to illustrate the usefulness and capabilities of the developed model.     

Stahl im Hochbau – ein nachhaltiger Werkstoff?

Steel for building constructions – a sustainable material? Since the Brundtland Report [12] “Our Common Future” 1985 and the Earth Summit of Rio 1992 “Sustainable Development” is omnipresent in our society: “Sustainable development is a development that meets the needs of the present without compromising the ability of future generations to meet their own needs“. The transmission of this concept into the building sector is called “Sustainable Construction“. Sustainable construction means to design and construct buildings with a holistic approach considering ecological, economical and sociocultural aspects ‐ a paradigm shift for the entire building sector. The “Austrian Steel Association” has commissioned the first mentioned author to point out in a pre‐feasibility study a SWOT‐analysis (strengths, weaknesses, opportunities and threats) of steel for constructions as well as to identify a future call for action for the steel construction industry. Three office buildings with load bearings systems made of steel, timber and reinforced concrete were compared. For the ecological assessment a life cycle analysis (LCA) on the basis of the ÖNORM EN ISO 14040 [25] was undertaken. Recycling or dismantling can not be depicted by life cycle assessments based on recent ISO draft standards. Within this work the ecological datasets for EAF‐steel (electric arc furnace) could be substantially improved.     

建设项目施工阶段环境影响评价研究

LCA(Life-Cycle Assessment)是评价产品从“摇篮到坟墓”(Cradle to Grave)的生命周期内对环境影响的一种评价方法。随着环境问题的日益严重,目前世界许多国家都在深入研究LCA在产品环境影响评价中的应用,并根据各自情况制定相应的评价模式和标准。本文按照LCA的评估原理,从评价的目标与范围界定、清单分析、影响评价和解释说明等四个环节,讨论如何运用LCA工具评估建设项目施工阶段的环境影响,建立具有可操作性的环境评价指标模型,对项目施工的环境友好性进行系统评价,从而改进建设项目环境管理,促进建筑业可持续发展。     

The changing role of life cycle phases, subsystems and materials in the LCA of low energy buildings

A detailed Life Cycle Assessment (LCA) has been conducted on a low energy family house recently built in Northern Italy. The yearly net winter heat requirement is 10 kWh/m², while the same unit with legal standard insulation would require 110 kWh/m². As the building was claimed to be sustainable on the basis of its outstanding energy saving performances, an ex post LCA was set up to understand whether, and to what extent, the positive judgement could be confirmed in a life cycle perspective. The dramatic contribution of materials-related impacts emerged. The shell-embedded materials represented the highest relative contribution, but maintenance operations also played a major role. The contributions of plants, building process and transportation were minor. The important role of the recycling potential also emerged. Unlike standard buildings, where heating-related impacts overshadow the rest of the life cycle, there is no single dominating item or aspect. Rather, several of them play equally important roles. The study has confirmed that the initial goal of environmental sustainability was reached, but to a much lower extent than previously thought. In comparison to a standard house, while the winter heat requirement was reduced by a ratio of 10:1, the life cycle energy was only reduced by 2.1:1 and the carbon footprint by 2.2:1.     

Environmental performance optimization of window-wall ratio for different window type in hot summer and cold winter zone in China based on life cycle assessment

This study aims at analyzing the environmental impact of each process of a typical office building over its entire life cycle in Shanghai, China, and finding out a suited limited value for window-wall ratio (WWR) of different orientation and window materials by comparing the results of different scenarios. Life cycle assessment (LCA) is used as a tool for the assessment of energy consumption and associated impacts generated from utilization of energy in building construction and operation.When looking at the impacts due to building external envelope production, we observed a small but significant environmental benefit as WWR increasing. Depending on the window materials, the impact is reduced by 9-15%. The environmental benefit associated with the changing in building external envelope production mainly results from the high coefficient of recovery of window materials, include window-frame and glass. But for building use phase, WWR with different window types or orientation has various effects on environmental burden. The environmental impact of office buildings is dominated by the operation stage, although the environmental burden of material production for low-E hollow glass window is larger than single glazing window, the environmental performance of building with low-E hollow glass window is better than other window materials.     

基于BIM的小型节能建筑生命周期环境影响和成本分析

被动式超低能耗建筑通过被动式设计策略、高性能的围护结构和高效的设备体系降低其使用阶段能耗。零能耗建筑在此基础上,采用太阳能光伏发电等可再生能源系统,进一步降低不可再生能源消耗。这两类节能建筑的材料和设备系统的隐含能耗、环境影响和成本通常高于一般建筑,同时对构件的后期维护和替换提出了更高的要求。因此,有必要从生命周期的范畴分析其环境和经济效益。建筑信息模型（BIM）能够为建筑项目的建造、运行和拆解等阶段提供多专业共享的数据平台。本文基于BIM,通过LCA和LCC方法对一座小型住宅建筑在不同节能目标情景下的生命周期全球变暖潜势值（GWP）、一次能耗（PE）和成本（LCC）进行分析和比较。结果表明,零能耗乃至正能源建筑在降低一次能耗和GWP方面具有明显优势,被动式超低能耗建筑也具有良好的环境效益。在经济效益方面,由于住宅建筑能源价格较低,如果按近年的价格指数计算,零能耗建筑和被动式超低能耗建筑的初建成本和后期构件替换成本增量将抵消其使用阶段节约的能耗成本,因此生命周期成本高于普通节能建筑。如果未来50年能源价格涨幅超过建筑安装价格涨幅,那么零能耗建筑在生命周期成本方面将具有优势。     

A BIM based tool for assessing embodied energy for buildings

Assessment of the energy associated with the material production,transportation and construction of buildings provides an opportunity for reducing the use of energy and improving sustainability. Building Information Modeling( BIM) provides a platform to incorporate sustainability information in the design of buildings. How ever,interoperability of BIMw ith Life Cycle Assessment( LCA) tools needs further investigation. Previous research in this area has either partially employed BIM; data wasexported from the main BIMauthoring tool and then auxiliary tools were utilized to evaluate the model,thereby causing a disconnect betw een the model and analysis resulting in non-interoperable systems,or has ignored the importance of retaining the LCA results within the BIMenvironment. To address this issue,this paper presents a framew ork to estimate the embodied energy content within the native BIMenvironment. The implementation of this framew ork is illustrated by the development of a tool for estimation of material embodied energy,transportation energy and construction energy. A prototype of the tool has been implemented on a case project to establish the workability of the framework.     

A newly developed life cycle inventory (LCI) database for commonly used structural steel components

The use of steel within the construction sector has enabled the delivery of larger-volume and more complex-shaped structures, while life cycle assessment (LCA) has been introduced as a pro-active design tool to ensure their sustainability. As LCA efficiency greatly depends on the life cycle inventory (LCI) data used, it is the purpose of the current research to present detailed structural steel LCI data and thus increase environmental benefits deriving from the effective use of LCA within construction. Hot-rolled structural steel members were chosen as the research starting point and the necessary information was provided by the leading structural steel manufacturer in Greece. Results include a list of environmental inputs and outputs, which can be used within relevant LCA studies and environmental impact assessment. Critical issues hindering the use of LCA were identified, along with the most environmentally damaging production stages and environmental categories mainly burdened. A new methodology for assessment results comparison was also applied.     

Net-positive building carbon sequestration

A greater appreciation of architecture as a means to drive social, economic and environmental sustainability is emerging around the world. Practices are beginning to adopt closed-loop and cradle-to-cradle strategies, and some are even aiming toward net-positive design. However, life cycle assessment (LCA) tools do not measure ‘beyond zero’. The question of how net-positive carbon sequestration (i.e. impacts beyond net-zero) can be assessed within LCA is explored through a proposed carbon amortization performance (CAP) method. CAP overlays energy-related carbon and biomass sequestration over the building life cycle. CO₂ equivalence (CO₂e) is used to combine both positive and negative impacts from different sources. Net-positive contributions are defined as those exceeding ‘zero operational carbon’ – after the embodied carbon is paid back during the life cycle. The CAP method was tested on a building design with the technical support of multidisciplinary experts. The results indicate that a building can sequester more carbon over its life cycle than it emits by using on-site current renewable energy technology and extensive building-integrated vegetation. Buildings designed on net-positive development principles can potentially reverse their carbon impact and begin to regenerate their regions, while providing multiple eco-services.     

A comparative life cycle assessment of a transparent composite façade system and a glass curtain wall system

High performance glass such as low-e coated or heat reflective glass offers better thermal performance, preventing undesired heat loss or gain during a building operation phase. However, these coatings may not be as effective in certain climate zones and create glare problems for adjacent buildings. A transparent composite façade system (TCFS) was newly configured to provide a sustainable alternative to a high performance glass wall in that the biofiber composite core acts as a shading device while the airspace between the polymer skins provides adequate insulation. A comparative life cycle assessment (LCA) method was selected as a sustainability measuring tool to compare the environmental impacts of a TCFS with a glass curtain wall system (GCWS). In this paper, the environmental performance of a façade system is characterized by the energy consumption and CO₂ emissions through all stages of the life cycle. Comparative LCA results show that the total life cycle energy of the TCFS is estimated to be 93% of that of the uncoated GCWS, and the total emissions of kg CO₂ equivalent for the TCFS is determined to be 89% of the uncoated GCWS. The use phase for both the TCFS and GCWS plays a dominant role in reducing environmental impacts while the impact associated with transportation and the end-of-life management is estimated to be insignificant in this study. The life cycle inventory data and analysis results provided in this paper are expected to assist designers with a better understanding of building material selection and system improvement from the whole life cycle perspectives.     

An analysis to understand how the shape of a concrete residential building influences its embodied energy and embodied carbon

The built environment is recognized as a major hotspot of resource use and environmental impacts. Life Cycle Assessment( LCA) has been increasingly used to assess the environmental impacts of construction products and buildings and a new trend is characterized by the application of LCA to larger systems such as neighborhoods during early design phases. Assessing urban development projects at the master-planning stage raises the issue of inventory data collection,especially for building materials which are reported to account for about 20%of primary energy consumption in buildings,and up to 45% of associated greenhouse gas emissions. Urban planners focus on the urban morphology and little information is know n about the buildings characteristics apart from their general shape. This paper proposes a simplified model for the assessment of buildings embodied energy and embodied carbon in relation w ith urban planners' design levers. The model relies on the decomposition of buildings into functional elements in order to be sensitive to the shape of the buildings. A detailed sensitivity analysis and contribution analysis of the model is conducted on two types of generic building forms,in order to investigate the influence of parameters relating to shape on the embodied energy and embodied carbon of a building. The sensitivity analysis show s that the parameters relating to shape( such as the dimension of the buildings) are more influential on the embodied energy and embodied carbon per square meter of building than the ones relating to the elements themselves( such as the wall thickness). The contribution analysis also brings evidence of the relation betw een the compactness factor and the embodied energy and embodied carbon of a building.     

Assessing the environmental performance of buildings: trends,lessons and tensions

ABSTRACT

Since the 1970s, intense discussions have occurred within the research and practitioner communities on how to assess and influence the environmental performance of buildings. Many different methods, criteria and tools were developed to raise awareness, enable goal formulation, support design and decision-making processes, and evaluate a building’s environmental performance. This development can be retraced through the example of the works of Raymond J. Cole, who made an important contribution to this scientific debate. The integration of environmental performance into a sustainability assessment, the ongoing development of life cycle assessment (LCA) methods, and clients’, financiers’ and assessors’ different demands for environmental performance assessment, raise additional questions and highlight the conflicting goals. Six topics are examined in relation to current developments: the further development of the classic ‘three pillars’ sustainability model; the suitability of assessment criteria and indicators; the handling of technological progress; the discounting of environmental impacts; the environmental assessment of existing buildings; and the further development of legal requirements. ‘Time’ is a key factor relating to LCA, weighing current versus future emissions, ecological value and recycling potential of existing buildings or ‘options’ for different ways to use the building in future. Recommended actions are provided for key stakeholders.     

Life cycle analysis of housing

This paper reports the findings of a project to assess the costs and benefits of adopting environment‐friendly construction practices for social rented housing in Scotland. Two contrasted dwelling specifications — one for a conventional building (the Control) and one for an environmentally responsible building (Eco‐Type 1) — are compared using Life Cycle Analysis and Life Cycle Costing methodologies. An assessment is made of the environmental and economic implications of adopting environmentally conscious construction practices in social rented housing. It is concluded that the provision of environmentally responsible dwellings could bring large‐scale reductions in the environmental burden of housing, and economic savings for housing providers and tenants over the life cycle of a dwelling with only a small increase in capital costs.     

Sustainability assessment of flooring systems in the city of Tehran: An AHP-based life cycle analysis

In recent years, numerous attempts have been made to reduce the global environmental and associated socio-economic impacts of construction activities to achieve sustainable development goals. A sustainable system or activity refers to an eco-friendly, cost effective and socio-politically viable solution. This paper utilizes triple-bottom-line (TBL) sustainability criteria for the selection of a sustainable flooring system in Tehran (Iran). Three types of block joisted flooring systems – concrete, clay, and expanded polystyrene (EPS) blocks – have been investigated using life cycle analysis (LCA). Proposed approach provides a comprehensive evaluation system based on TBL criteria that are further divided into thirteen sub-criteria. It includes: (1) Environmental concerns (resource depletion, waste and emissions, waste management, climate change, environmental risk, embodied energy and energy loss); (2) Economic concerns (material cost, construction cost, and occupation and maintenance cost); and (3) Socio-political issues (social acceptance, vulnerability of area, and building weight). Analytical hierarchy process (AHP) is used as a multi-criteria decision making technique that helps to aggregate the impacts of proposed (sub)criteria into a sustainability index (SI) through a five-level hierarchical structure. Integration of AHP and LCA provides a framework for robust decision making that is consistent with sustainable construction practices. A detailed analysis shows that the EPS block is the most sustainable solution for block joisted flooring system in Tehran.     

Integrated assessment method for building life cycle environmental and economic performance

Life cycle assessment (LCA) is a powerful tool to identify a building’s environmental impact throughout its life cycle. However, LCA does have limits in practice because it does not consider the economic aspect of project implementation. In order to promote LCA application, a more comprehensive evaluation of building life cycle environmental and economic performance must be performed. To address these issues, we propose life cycle green cost assessment (LCGCA), a method that combines LCA with life cycle costing (LCC). In LCGCA the building’s environmental loads are converted to environmental costs based on the trading price of CO₂ certified emission reductions (CERs). These environmental costs are then included into the building life cycle cost. Subsequently an evaluation index of green net present value (GNPV) for LCGCA can be obtained. A governmental office building in Beijing was studied using LCGCA. Several design options were compared and the sensitivity of the CER price was analyzed. The research also shows that conclusions reached by LCGCA may be different from those of traditional LCC, which does not include environmental costs. The application of LCGCA needs the support of environmental policies. A sound environmental tax mechanism is expected to be established in China soon, which will enable LCGCA to be a useful tool to guide sustainable building design efficiently.     

LCA profiles for building components: strategies for the early design process

Construction professionals are required to integrate environmental concerns in the earliest design phases. However, environmental assessments need large amounts of precise data that are typically not available in the early design process, as most variables are still fluid. To address this concern, a new approach explores how environmental information on building components can be simplified for strategic use early in the design process in a Danish context. In this paper, life cycle assessments (LCAs) are undertaken for several hundred typical external wall solutions, based on relevant standards. A full bivariate linear regression analysis is performed, showing statistically significant correlations with strong direct relationships between environmental impact categories. A simplified LCA profile consisting of total primary energy, global warming potential and acidification potential is developed. This simplified LCA profile presents environmental data in a more understandable way, creating a strategic overview that can be easily used by non-technical clients and construction professionals in the early design stages. This has a scientific and statistical validity generated by environmental assessment standards, and creates a parallel between the precision of the approach and its time of use in the design process.