An LCA-based environmental impact assessment model for construction processes

A quantitative assessment of the environmental impact of construction activities can help decision-makers identify major environmental impact factors and make environmentally friendly construction plans in the early stages of construction. This paper presents an integrated life cycle environmental impact assessment model that is applicable to construction phase studies, where impact factors are examined according to two aspects of a typical construction process: construction equipment and ancillary materials. Environmental impacts are categorized into three safeguard subjects: ecosystems, natural resources and human health. A disability adjusted life year (DALY) model for assessing human health damage due to construction dust is developed. In addition, the environmental impact of earthwork construction is assessed as a case study to demonstrate the application of the proposed model. Results indicate that the proposed model can effectively quantify the environmental impacts of construction processes, and can potentially be used as a tool for contractors to select environmentally friendly construction plans.     

Using life cycle assessment to derive an environmental index for light-frame wood wall assemblies

Following a life cycle assessment (LCA) approach, this study aims at defining an appropriate performance index to consider environmental impact in the development of a multicriteria evaluation comparing factory-built wood-frame exterior walls. The investigation is applied to a case study comparing five wall assemblies for the exterior wall of a residential building in Quebec City (Canada). For the five alternatives, the life cycle inventory (LCI) provided by the ATHENA™ Environmental Impact Estimator software is aggregated using three different life cycle impact assessment (LCIA) methods: IMPACT 2002+, Eco-indicator 99 and TRACI. The relative impacts of assembly components and of the operation energy source on the environmental performance of the assemblies are investigated by comparing midpoint and endpoint indicators calculated with the three LCIA methods. The study concludes to the acceptability, in this specific context, of using the climate change indicator as an appropriate environmental index.     

BEPAS—a life cycle building environmental performance assessment model

This paper presents a building environmental performance analysis system—BEPAS, which was developed based on the life cycle assessment (LCA) framework. In BEPAS, environmental impacts were investigated in three main aspects of a building that were closely related to environmental performance—building facilities, building materials and location. In addition, a set of environmental databases were developed, covering the environmental performance profiles of these environmental aspects. The BEPAS can be used to assess the environmental performance of a new or existing building. This paper also discusses a case project in order to illustrate the assessment procedures and test the effectiveness of the system in application.     

沥青混凝土生命周期环境影响评价研究

沥青混凝土在生产、铺筑和废弃过程中会消耗大量的自然资源和能源,因此有必要对其开展生命周期环境影响评价.采用生命周期评价方法,对沥青混凝土生命周期过程中的资源、能源消耗及污染物排放进行了评价.结果表明,沥青混凝土生命周期中能耗最大的是拌和过程,环境负荷影响类型重要性的大小依次为:不可再生资源＞温室效应＞酸化效应＞光化学烟雾＞人体健康损害;不同生产阶段的环境影响大小依次为:原材料生产过程＞运输过程＞拌和过程＞废弃过程＞摊铺压实过程.     

An embodied carbon and energy analysis of modern methods of construction in housing: A case study using a lifecycle assessment framework

There is a growing interest in comparing the energy and consequential carbon embodied in buildings using different methods of construction and alternative materials. This paper compares the embodied carbon in a low energy, affordable house constructed using a novel offsite panellised modular timber frame system, in Norfolk UK with two traditional alternative scenarios. A lifecycle assessment (LCA) framework is used to conduct a partial LCA, from cradle to site, of the construction. An inventory of the materials and fossil fuel energy utilised in the construction was used to calculate the primary energy consumed and the associated embodied carbon. The embodied carbon was found to be 34.6 tonnes CO₂ for a 3 bedroom semi-detached house, 405 kgCO₂ per m² of useable floor area. When compared with traditional methods of construction the modern methods of construction (MMC) house resulted in a 34% reduction in embodied carbon. Despite timber being the predominant structural and cladding material, concrete is the most significant material (by proportion) in embodied carbon terms, responsible for 36% of materials related embodied carbon.     

Environmental assessment of brick production in Greece

Brick constitutes one of the major materials used for the construction of buildings. The present study analyses the different stages followed during brick production and the materials and energy used in each stage. The purpose is to identify ‘hot-spots’, i.e. parts of the life cycle that are important to the total environmental impact. The analysis is performed using life cycle assessment (LCA) methodology, which is a method used to identify and quantify the environmental performance of a process or a product from “cradle to grave”. LCA methodology provides a quantitative basis for assessing potential improvements in environmental performance of a system throughout the life cycle. The system investigated includes raw material acquisition, industrial production, packaging and transportation. Energy use and emissions are quantified and the potential environmental effects are assessed. The main energy inputs to the production system are electricity, diesel and solid fuel (Pet-Coke). The environmental burdens that arise from the operation of a brick industry are mainly due to air emissions derived from fossil fuel utilization.     

Modern method of construction based on wood in the context of sustainability

Global developments in construction give sustainability a crucial role in overall healthy functioning of society as well as the whole environment. Modern Methods of Construction (MMC) represent a response to the sustainability trend, since they bring faster construction and better environmental, energy and economic parameters. The aim of this article is to analyse and evaluate the benefits of MMC in the form of Prefabricated Panel Wood Construction (PWC). With the aid of a case study, certain environmental and economic parameters of PWC on the one hand and traditional Masonry Construction (MC) from ceramic bricks on the other hand will be studied and compared. The environmental evaluation of building material composition was conducted by means of the ‘Cradle to Gate’ model within the LCA method. The parameters in question will be studied in terms of embodied energy, global warming potential and acidification potential. The economic parameters to be analysed include construction time, construction costs and particularly the environmental burden caused by transport of materials to the building site. The submitted experimental study and its results should help break barriers sustained by traditional technologies and point towards healthier and more environmentally friendly alternatives in construction processes.     

Options to reduce the environmental impacts of residential buildings in the European Union—Potential and costs

A typology of buildings representative of the building stock for the EU-25 was developed characterizing 72 building types in terms of their representativity, geographical distribution, size, material composition, and thermal insulation. The life cycle impacts of the building types were calculated for different environmental impact categories both at building and EU-25 level. The use phase of buildings, dominated by the energy demand for heating is by far the most important life cycle phase for existing and new buildings. The environmental impacts were allocated to single building elements. Ventilation, heat losses through roofs and external walls are important for a majority of single- and multi-family houses. Three improvement options were identified: additional roof insulation, additional façade insulation and new sealings to reduce ventilation. The measures yield a significant environmental improvement potential, which, for a majority of the buildings types analyse represent at least 20% compared to the base case. The major improvement potentials at EU-level lie with single-family houses, followed by multi-family houses. Smaller reductions are expected for high-rise buildings due to the smaller share in the overall building stock. For both roof insulation and reduced ventilation, the measures were shown to be economically profitable in a majority of buildings.     

An economic input-output life cycle assessment of food transportation in Thailand

This study applies an economic input-output life cycle assessment (EIO-LCA) approach for 180 industrial sectors of the Thai economy. The approach is used to evaluate energy consumption and CO₂ emissions of the agricultural sector for the entire supply chain and particularly focusing on transportation. Transportation emits the second largest amount of CO₂ by sector in Thailand. Road transportation is the dominant form of cargo transport, accounting for 80% of all modes. The results show that transportation emissions from all modes of cargo transport account for 1–6% of total supply chain emissions. The vegetable sector shares highest CO₂ emissions in transportation. By changing the transportation mode from road freight to rail, emissions could be expected to decline. If 50% of road transportation was shifted to rail, CO₂ emissions would drop by 30%.     

高速公路建设中地下水环境影响评价初探

探讨了高速公路建设中地下水环境影响评价的目的、依据、方法和内容,分析了高速公路建设对地下水环境的影响,并提出了防治措施与建议,对建设区地下水环境保护、生态文明建设及高速公路工程的合理施工与运营有着重要的意义。     

预拌混凝土生命周期环境影响评价

预拌混凝土是目前重点推广和用量巨大的建筑材料。为客观评价预拌混凝土的环境影响,基于BEPAS(Building Environmental Performance Analysis System)评价系统,从六种等级预拌混凝土(C30～C100)的生产、施工、拆除三个阶段的资源和能源消耗基础数据收集入手,建立了各等级预拌混凝土的投入产出清单。依据更新的货币化环境影响评价权重,得到了单位体积预拌混凝土的生命周期社会意愿支付值。此外,给出了基于6个模拟算例的混凝土框架结构的环境影响评价结果。结果表明:单一预拌混凝土材料的环境影响随等级提高而上升;对于框架结构,C50和C60高强预拌混凝土兼具环境表现和经济效果良好的特点。     

钢筋混凝土顶管施工工艺

以顶管施工为例,从顶管方法、顶管平台下管、顶管洞门开启等方面详细地阐述了顶管施工要点,并提出相应的施工质量保证措施及施工现场的安全管理措施,从而确保了顶管工程顺利的穿越矿区中心路,达到了预期目的。     

Alternative scenarios analysis concerning different types of fuels used for the coverage of the energy requirements of a typical apartment building in Thessaloniki, Greece. Part II: life cycle analysis

This paper constitutes a continuation of “Alternative scenarios analysis concerning different types of fuels used for the coverage of the energy requirements of a typical apartment building in Thessaloniki, Greece. Part I: fuel consumption and emissions”. It is concerned with the application of life cycle analysis (LCA) methodology to the model of the apartment building determined in Part I. The examination here includes emissions of light heating oil EL refining, transportation and combustion, of natural gas transportation and combustion and of electricity generation and use (lignite, natural gas, diesel oil and kerosene originated). All data used were collected from a typical power station in Greece.     

Monitoring trends of urban development and environmental impact of Beijing, 1999-2006

The high rates of environmental change and accelerated species loss in the urban development process should be quantified to rebalance the social and environmental dimensions of sustainability. In this study, an emergy-based environmental impact assessment model is designed according to the framework of the Eco-Indicator 99 for monitoring the negative effects on human well-being and ecosystem integrity in the urban development system of Beijing from 1999 to 2006. The environmental impact assessment model is based on the sustainability promotion perspective, and emphasizes the determinants of human health and ecosystem integrity in the urban development process. It is vital that the links among human health, ecosystem integrity and urban sustainability are therefore considered especially from the perspective of a supply-side environmental cost evaluation (including ecological service supply, ecological and economic losses and investment for treatment). Results suggest that: (1) out of all the pollutants, ecological services were mainly used to dilute sulfur dioxide and NH₃-N; (2) nitrogen dioxide and greenhouse gases released by the urban system contribute heavily to both ecological and economic losses evaluated in emergy terms; and (3) emissions impact, mainly from airborne pollutants, with small contribution from waterborne emissions, generally increases from 1999 to 2006, undermining the sustainability of Beijing. The emergy synthesis proves to be very appropriate to account for large-scale and indirect costs generated by pollution as side effects of economic activity. Such knowledge is a necessary pre-requisite to perform a reliable cost-benefit evaluation of urban sustainability strategies, and provide guidance for policy decision making to maximize benefits and minimize negative impacts.     

Life cycle assessment of residential heating and cooling systems in four regions in the United States

Heating and cooling systems consume the most energy and are the largest source of emissions in the entire life cycle of a house. This study compares the life cycle impacts of three residential heating and cooling systems—warm-air furnace and air-conditioner, hot water boiler and air-conditioner, and air–air heat pump over a 35-year study period. Simulation and life cycle assessment studies of the systems at four locations in the United States, namely Minnesota, Oregon, Pennsylvania and Texas determine the effect of regional variations in climate, energy mix, and the standard building characteristics on the systems’ environmental impacts.     

锈蚀对钢筋混凝土梁的影响

采用六种不同类型的梁进行了试验研究,探讨了锈蚀对钢筋混凝土梁的影响,通过向混凝土梁环境中添加氯化钙加速锈蚀,分析了由于钢筋的锈蚀,对钢筋混凝土梁的极限承载力及跨中变形的影响规律。     

公路环境保护与环境影响评价

通过对公路建设环境保护深入地分析与探讨，总结归纳了公路施工、营运期环境保护工作的重点与措施，并对环境影响评价制度与方法进行了全面阐述，以提高公路建设及环境治理水平。     

钢筋混凝土结构免预压法施工技术

结合大同大学体育馆工程，提出了采取大跨度钢筋混凝土拱方案，介绍了大跨度拱施工的技术难点及其工艺原理，对支撑体系的选择与优化、模板工程、钢筋工程、混凝土工程和落架的施工要点和施工工艺进行了详细阐述，为拱结构的设计研究和制定施工方案提供了理论依据。     

型钢混凝土结构的深化设计和施工

结合工程实例,介绍型钢混凝土组合结构施工工艺及施工难点,通过对型钢混凝土二次深化设计,对关键节点进行处理,合理安排工序,确保质量及工程施工进度。     

LCA-based environmental assessment of the use and maintenance of heating and ventilation systems in Dutch dwellings

Buildings contribute significantly to the human-induced environmental burden. This comes not only from construction and demolition but also from activities throughout the operational phase – building maintenance and energy use for climate control. This paper describes how life cycle assessment (LCA) methodology can be applied to quantitatively assess the environmental performance of the use and maintenance of heating and ventilation systems. The studied climate systems include individual non-condensing boilers, condensing boilers and heat pumps on exhaust air for heating and hot tap water combined with either collective mechanical exhaust ventilation or individual balanced ventilation with heat recovery. This study shows that a heat pump causes the highest environmental burden of all the assessed climate systems due to the electricity needed for operation, high material content of the system and the refrigerant used. If the electricity used by the heat pump is generated fully by local photovoltaic cells, environmental performance will improve, but not for all environmental impact categories. Climate systems that reduce energy demand for heating, such as ventilation with heat recovery, will reduce the environmental impact related to energy use for space heating. However, if the electricity used to operate the system increases, along with the material content of the systems and distribution networks, other environmental impact categories than those related to space heating will also increase. Finally, maintenance frequency and related transportation of maintenance workers have a marginal effect on total environmental impact.