基于LCA的低强再生碎砖混凝土的环境效益评估

基于LCA生命周期评价理论,计算目标强度分别为5、10、15 MPa的低强再生碎砖混凝土及普通混凝土C15的负荷量,并且对两者进行比较,进行再生碎砖混凝土环境评价.结果表明生产再生混凝土的电耗量、煤耗量及耗油量都比普通混凝土少,并且环境负荷排放量比普通混凝土少,所以回收利用建筑垃圾对从环境保护来说意义重大.     

Life cycle assessment in buildings: State-of-the-art and simplified LCA methodology as a complement for building certification

The paper presents the state-of-the-art regarding the application of life cycle assessment (LCA) in the building sector, providing a list of existing tools, drivers and barriers, potential users and purposes of LCA studies in this sector. It also proposes a simplified LCA methodology and applies this to a case study focused on Spain. The thermal simulation tools considered in the Spanish building energy certification standards are analysed and complemented with a simplified LCA methodology for evaluating the impact of certain improvements to the building design. The simplified approach proposed allows global comparisons between the embodied energy and emissions of the building materials and the energy consumption and associated emissions at the use stage.The results reveal that embodied energy can represent more than 30% of the primary energy requirement during the life span of a single house of 222 m² with a garage for one car. The contribution of the building materials decreases if the house does not include a parking area, since this increases the heated surface percentage. Usually the top cause of energy consumption in residential building is heating, but the second is the building materials, which can represent more than 60% of the heating consumption.     

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.     

Life cycle assessment of residential ventilation units in a cold climate

The life cycle assessment (LCA) methodology is used in this paper to assess the environmental impacts of residential ventilation units over a 50 year life cycle in Finland. Quantifying the consumption of the energy and material resources during the life cycle permits the estimation of the harmful emissions into the environment (air, water and soil) and the potential changes in the environment (climate change, acidification and ozone production). Two different ventilation units are evaluated, both of which include air-to-air energy exchangers. The research demonstrates that a residential ventilation unit, with a function of providing 50 l/s of outdoor ventilation air, but not heating the air, has a net positive impact on the environment when it is equipped with a air-to-air energy exchanger with an effectiveness greater than 15%. The greater the effectiveness, the greater the positive impact on the environment.     

建筑垃圾制免烧免蒸砖的环境影响评价

随着城镇建设的快速发展,建筑垃圾剧增,对环境和社会的影响越加严重,建筑垃圾的减量化、资源化和再利用成为建筑业可持续发展亟待解决的问题。免烧免蒸砖是一种替代传统粘土实心砖的新型墙体材料,有利于节能、节地、利废,促进循环经济发展,具有良好的经济效益和社会效益。文章通过对建筑垃圾制免烧免蒸砖生产工艺的调查,系统分析了生产过程的各项环境排放因素,并运用生命周期评价理论和方法,对其生产过程的环境影响进行定量研究和综合测算。针对建筑垃圾制免烧免蒸砖的生产过程中主要环境影响因素,包括温室气体和粉尘的排放等,提出了改进建议。     

Eco-Bat: A design tool for assessing environmental impacts of buildings and equipment

This paper presents the features of Eco-Bat, a computer program developed to assess the environmental impacts of buildings, including construction materials and energy consumed, during its life cycle. The methodology used to evaluate environmental impacts based on a life cycle assessment (LCA) approach, compatible with ISO 14040 standards, is detailed. The data are mainly extracted from an environmental impacts database, Ecoinvent, which contains values for the manufacturing and elimination of numerous materials as well as other processes. Two applications are presented to illustrate the possibilities offered by Eco-Bat. The first one is a comparison of different variants of building facades. The second example shows the analysis of a whole building including its energy consumption.     

Comparative life cycle analysis for green façades and living wall systems

Greening the building envelope focusing on green façades with vegetation is a good example of a new construction practice. Plants and partly growing materials in case of living wall systems (LWS) have a number of functions that are beneficial, for example: increasing the biodiversity and ecological value, mitigation of urban heat island effect, outdoor and indoor comfort, insulating properties, improvement of air quality and of the social and psychological well being of city dwellers.This paper discusses a comparative life cycle analysis (LCA) situated in The Netherlands for: a conventional built up European brick façade, a façade greened directly, a façade greened indirectly (supported by a steel mesh), a façade covered with a living wall system based on planter boxes and a façade covered with a living wall system based on felt layers. Beside the environmental benefits of the above described greening systems, it is eventually not clear if these systems are sustainable, due to the materials used, maintenance, nutrients and water needed.A LCA is used to analyze the similarity and differences in the environmental impacts in relation with benefits estimated for two climate types for building energy saving (reduction of electrical energy used for building cooling and heating).     

Life cycle inventory of buildings: A calculation method

Traditionally, life cycle assessment (LCA) is mostly concerned with product design and hardly considers large systems, such as buildings, as a whole. Though, by limiting LCA to building materials or building components, boundary conditions, such as thermal comfort and indoor air quality, cannot be taken into account. The life cycle inventory (LCI) model presented in this paper forms part of a global methodology that combines advanced optimisation techniques, LCI and cost-benefit assessment to optimise low energy buildings simultaneously for energy, environmental impact and costs without neglecting the boundary conditions for thermal comfort, indoor air quality and legal requirements for energy performance. This paper first outlines the goal and scope of the LCI. Then, the partial inventory models as well as the overall building inventory model are presented. Finally, the LCI results are shown and discussed for one reference dwelling for the context of Belgium.     

Life cycle primary energy use and carbon emission of an eight-storey wood-framed apartment building

In this study the life cycle primary energy use and carbon dioxide (CO₂) emission of an eight-storey wood-framed apartment building are analyzed. All life cycle phases are included, including acquisition and processing of materials, on-site construction, building operation, demolition and materials disposal. The calculated primary energy use includes the entire energy system chains, and carbon flows are tracked including fossil fuel emissions, process emissions, carbon stocks in building materials, and avoided fossil emissions due to biofuel substitution. The results show that building operation uses the largest share of life cycle energy use, becoming increasingly dominant as the life span of the building increases. The type of heating system strongly influences the primary energy use and CO₂ emission; a biomass-based system with cogeneration of district heat and electricity achieves low primary energy use and very low CO₂ emissions. Using biomass residues from the wood products chain to substitute for fossil fuels significantly reduces net CO₂ emission. Excluding household tap water and electricity, a negative life cycle net CO₂ emission can be achieved due to the wood-based construction materials and biomass-based energy supply system. This study shows the importance of using a life cycle perspective when evaluating primary energy and climatic impacts of buildings.     

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.     

A greenhouse gas assessment of a stadium in Australia

A greenhouse gas (GHG) life cycle assessment (LCA) was performed on a stadium used for sporting events in a subtropical region in Australia. Inventories for the construction and operation of a stadium are presented and the GHG emissions from construction, operations and end-of-life waste management are assessed against the attendance of one person at one event. The inclusion of additional economic activities, patron travel, LCA methodology, attendance and stadium life-time assumptions are likely to affect the overall magnitude of the GHG emissions of one person's attendance. The assessment shows that the stadium operation accounted for 72.5% of GHG emissions, with the operation of baseload heating, ventilation and cooling, lighting and refrigeration systems dominating. The best opportunity to reduce GHG emissions is to reduce the need for the continual operation of these systems. Construction impacts account for 24.7% of impacts, while replacement materials, end-of-life management of materials are relatively insignificant, contributing to less than 3% of life cycle GHG emissions.     

A life cycle assessment of in-place recycling and conventional pavement construction and maintenance practices

The application of in-place recycling techniques has emerged as a practical and effective way to enhance the sustainability of agency pavement management decisions for asphalt-surfaced pavements. However, the potential environmental benefits resulting from applying in-place recycling techniques have not been fully documented in the literature. This paper presents a comprehensive pavement life cycle assessment (LCA) model that extends the typical pavement LCA's system boundaries to include the environmental impacts resulting from the usage phase and the production of the energy sources. The results of the application of the pavement LCA model to a specific highway rehabilitation project in the state of Virginia showed that in-place recycling practices and an effective control of the pavement roughness can improve significantly the life cycle environmental performance of a pavement system.     

Energy consumption and exhaust emissions in mechanized timber harvesting operations in Sweden

The study presents an estimation of the energy input and the amount of emissions to air due to fuel, chainsaw and hydraulic oil consumption by heavy duty diesel engine vehicles operating in forest logging operations in Sweden. Exhaust concentrations are given for carbon dioxide, carbon monoxide, nitrogen oxides, hydrocarbons and particulate matter. Three fuel types (rapeseed methyl ester, environmental class 1 and environmental class 3 diesel fuels) and two types of lubricating base oil (mineral- and vegetable-based) were examined. Energy input per unit of timber production (m3ub) was 82 MJ, 11% of which was due to energy consumption during the production phase of the fuel. Emissions during the whole life cycle of the fuels and the base oils are included in the study. The highest CO2 and NOx emissions occurred when rapeseed methyl ester was used as fuel together with rapeseed as base oil for chainsaw and hydraulic oil. The highest HC and CO emissions occurred when environmental class 3 diesel fuel was used.     

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.     

Energy use, CO2 emissions and waste throughout the life cycle of a sample of hotels in the Balearic Islands

Tourism is the most developed economic sector in the Balearic Islands. The great rise in construction activities within the last 50 years, the increase in energy use, in CO₂ emissions and in waste production due to tourism, as well as an electrical energy production system mainly based on coal and fossil fuels is not an environmentally sustainable scenario. The aim of this study is to identify the processes that have had the greatest impact on the life cycle of a tourist building. In order to do this, the energy uses, CO₂ emissions and waste materials generated have been estimated, assuming a life cycle of 50 years, within a sample of hotels from the Balearic Islands. The results show that the operating phase, which represents between 70% and 80% of the total energy use, is the one with the greatest impact; that the energy use due to the manufacture of materials represents a fifth of the total and that electric consumption is the main cause of CO₂ emissions because of the regional energy system.     

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.     

Inventory analysis of LCA on steel- and concrete-construction office buildings

A life-cycle inventory model for the office buildings is developed in this paper. The environmental effects of two different building structures, steel and concrete, are intercompared. The results show that the steel-framed building is superior to the concrete-framed building on the following two indexes, the life-cycle energy consumption and environmental emissions of building materials. It is found that the life-cycle energy consumption of building materials per area in the steel-framed building is 24.9% as that in the concrete-framed building, whereas, on use phase, the energy consumption and emissions of steel-framed building are both larger than those of concrete-framed building. As a result, lower energy consumption and environmental emissions are achieved by the concrete-framed building compared with the steel-framed building on the whole life cycle of building. The present study also provides a good method of assessing the performance of energy saving and environmental protection of different building structures based on a whole life cycle.     

A thermodynamic method to calculate energy &amp; exergy consumption and CO<Subscript>2</Subscript> emission of building materials based on economic indicator

Due to the data deficiency in developing countries like China, the calculation of the building production phase only considers a few major materials. To solve this problem, three indexes are put forward, which are cost-based energy, cost-based exergy and cost-based carbon, and a new concept, the equivalent coefficient of thermodynamic cost, is presented based on social economic indicator, energy intensity. Then a thermodynamic method is built up to estimate the energy, exergy consumption and CO₂ emission of building materials in production phase. Compared to the conventional calculation, this thermodynamic method takes full account of every material in the BOQ (bill of quantity), and the data used in the method, energy intensity, can be found in government publications. The production phase of the case building is analyzed using this method, and results show that the production phase accounts for 12.34% of the life cycle energy consumption, also contributes 15.48% towards the life cycle CO₂ emissions. The embodied energy of the case building is about 4.995 GJ/m² which matches the results from other LCA research, thus verifies the validity of the proposed calculation. This method is practical and significant in improving sustainable building assessment tools and enacting energy policies in building sector.     

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.     

Life cycle of buildings,demolition and recycling potential: A case study in Turin,Italy

One of the most challenging issues presently facing policymakers and public administrators in Italy concerns what to do with waste materials from building dismantling activities and to understand whether, and to what extent, the ever-increasing quantity of demolition waste can replace virgin materials. The paper presents the results from a research programme that was focused on the life cycle assessment (LCA) of a residential building, located in Turin, which was demolished in 2004 by controlled blasting. A detailed LCA model was set-up, based on field measured data from an urban area under demolition and re-design, paying attention to the end-of-life phase and supplying actual data on demolition and rubble recycling. The results have demonstrated that, while building waste recycling is economically feasible and profitable, it is also sustainable from the energetic and environmental point of view. Compared to the environmental burdens associated with the materials embodied in the building shell, the recycling potential is 29% and 18% in terms of life cycle energy and greenhouse emissions, respectively. The recycling potential of the main building materials was made available in order to address future demolition projects and supply basic knowledge in the design for dismantling field.