Building-related embodied impacts are growing and should not be ignored.  Ways of improving transparency in embodied impact assessments are proposed.  Actor-specific guidelines can foster integration of embodied impacts into practice.  The availability of quality-checked databases can support the entire process.  A number of strategies for the reduction of embodied impacts are demonstrated.

Abstract:As the greenhouse gas reduction goal of 37% below business-as-usual (BAU) by 2030, the construction industry is recognized as an anti-environment industry for mass consumption/mass waste; thus, members of the industry are requested to make efforts to transform it into an environment-friendly industry. Concrete, a common construction material, is known to emit large amounts of environmentally hazardous waste during the processes related to its production, construction, maintenance, and demolition. The amount of greenhouse gas (GHG) emissions by the product is specified in a ready-mixed concrete report whenever concrete is sold commercially. Hence, there have been many studies addressing the quantitative evaluation and reduction of the environmental effects of concrete. This study aims to introduce a method for assessing the amount of carbon dioxide emission from the processes of producing concrete. Moreover, we measured the quantities of CO 2 emission of about 10 under-construction projects, including office buildings, apartment buildings, and high-rise residential buildings in South Korea. Using the assessment result, we analyzed the CO 2 reduction performance of an office building in South Korea and drew conclusions about measures for reducing CO 2 emission.

There have been much interest and many efforts to control global warming and reduce greenhouse gas (GHG) emissions throughout the world. Recently, the Republic of Korea has also increased its GHG reduction goal and searched for an implementation plan. In buildings, for example, there have been technology developments and deployment policies to reduce GHG emissions from a life cycle perspective, covering construction materials, building construction, use of buildings and waste disposal. In particular, Korea's Green Standard for Energy and Environmental Design is a certification of environmentally-friendly buildings for their energy saving and reduction of environmental pollution throughout their lives. In fact, the demand and adoption of the certification are rising every year. In construction materials and buildings, as a result, an environmentally-friendly aspect has become crucial. The importance of construction material and building development technologies that can reduce environmental load by diminishing GHG emissions in buildings has emerged. Moreover, there has been a rising necessity to verify the GHG reduction effects of buildings. To assess the reduction of carbon emissions in the buildings built with low-carbon construction technologies and materials, therefore, this study estimated life cycle carbon emissions in reference buildings in which general construction materials are used and in low-carbon buildings. For this, the carbon emissions and their reduction from construction materials (especially concrete) between conventional products and low-carbon materials were estimated, using Life Cycle Assessment (LCA). After estimating carbon emissions from a building life cycle perspective, their reduction in low-carbon buildings compared to the reference buildings was reviewed. The results found that compared to conventional buildings, low-carbon buildings revealed a 25% decrease in carbon emissions in terms of the reduction of Life Cycle CO 2 (LCCO 2 ) per unit area. If diverse production technologies and sales routes are further developed for low-carbon construction materials, carbon emission reduction effects would considerably increase.

Concrete is a major material used in the construction industry that emits a large amount of substances with environmental impacts during its life cycle. Accordingly, technologies for the reduction in and assessment of the environmental impact of concrete from the perspective of a life cycle assessment (LCA) must be developed. At present, the studies on LCA in relation to greenhouse gas emission from concrete are being carried out globally as a countermeasure against climate change. However, the studies on the impact of the substances emitted in the concrete production process on acidification and eutrophication are insufficient. As such, assessing only a single category of environmental impact may cause a misunderstanding about the environmental friendliness of concrete. The substances emitted in the concrete production process have an impact not only on global warming but also on acidification and eutrophication. Acidification and eutrophication are the main causes of air pollution, forest destruction, red tide phenomena, and deterioration of reinforced concrete structures. For this reason, the main substances among those emitted in the concrete production process that have an impact on acidification and eutrophication were deduced. In addition, an LCA technique through which to determine the major emissions from concrete was proposed and a case analysis was carried out. The substances among those emitted in the concrete production process that are related to eutrophication were deduced to be NO x , NH 3 , NH 4 + , COD, NO 3´, and PO 4 3´. The substances among those emitted in the concrete production process that are related to acidification, were found to be NO x , SO 2 , H 2 S, and H 2 SO 4 . The materials and energy sources among those input into the concrete production process, which have the biggest impact on acidification and eutrophication, were found to be coarse aggregate and fine aggregate.

Abstract:Concrete is a type of construction material in which cement, aggregate, and admixture materials are mixed. When cement is produced, large amounts of substances that impact the environment are emitted during limestone extraction and clinker manufacturing. Additionally, the extraction of natural aggregate causes soil erosion and ecosystem destruction. Furthermore, in the process of transporting raw materials such as cement and aggregate to a concrete production company, and producing concrete in a batch plant, substances with an environmental impact are emitted into the air and water system due to energy use. Considering the fact that the process of producing concrete causes various environmental impacts, an assessment of various environmental impact categories is needed. This study used a life cycle assessment (LCA) to evaluate the environmental impacts of concrete in terms of its global warming potential, acidification potential, eutrophication potential, ozone depletion potential, photochemical ozone creation potential, and abiotic depletion potential (GWP, AP, EP, ODP, POCP, ADP). The tendency was that the higher the strength of concrete, the higher the GWP, POCP, and ADP indices became, whereas the AP and EP indices became slightly lower. As the admixture mixing ratio of concrete increased, the GWP, AP, ODP, ADP, and POCP decreased, but EP index showed a tendency to increase slightly. Moreover, as the recycled aggregate mixing ratio of concrete increased, the AP, EP, ODP, and ADP decreased, while GWP and POCP increased. The GWP and POCP per unit compressed strength (1 MPa) of high strength concrete were found to be about 13% lower than that for its normal strength concrete counterpart. Furthermore, in the case of AP, EP, ODP, and ADP per unit compressed strength (1 MPa), high-strength concrete was found to be about 10%~25% lower than its normal strength counterpart. Among all the environmental impact categories, ordinary cement was found to have the greatest impact on GWP, POCP, and ADP, while aggregate had the most impact on AP, EP, and ODP.

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.

Abstract:To comply with recent international trends and initiatives, and in order to help achieve sustainable development, Korea has established a greenhouse gas (GHG) emission reduction target of 37% (851 million tons) of the business as usual (BAU) rate by 2030. Regarding environmentally-oriented standards such as the IGCC (International Green Construction Code), there are also rising demands for the assessment on CO 2 emissions during the life cycle in accordance with ISO (International Standardization Organization's Standard) 14040. At present, precast concrete (PC) engineering-related studies primarily cover structural and construction aspects, including improvement of structural performance in the joint, introduction of pre-stressed concrete and development of half PC. In the manufacture of PC, steam curing is mostly used for the early-strength development of concrete. In steam curing, a large amount of CO 2 is produced, causing an environmental problem. Therefore, this study proposes a method to assess CO 2 emissions (including absorption) throughout the PC life cycle by using a life cycle assessment (LCA) method. Using the proposed assessment method, CO 2 emissions during the life cycle of a precast concrete girder (PCG) were assessed. In addition, CO 2 absorption was assessed against a PCG using conventional carbonation and CO 2 absorption-related models. As a result, the CO 2 emissions throughout the life cycle of the PCG were 1365.6 (kg-CO 2 /1 PCG). The CO 2 emissions during the production of raw materials among the CO 2 emissions throughout the life cycle of the PCG were 1390 (kg-CO 2 /1 PCG), accounting for a high portion to total CO 2 emissions (nearly 90%). In contrast, the transportation and manufacture stages were 1% and 10%, respectively, having little effect on total CO 2 emissions. Among the use of the PCG, CO 2 absorption was mostly decided by the CO 2 diffusion coefficient and the amount of CO 2 absorption by cement paste. The CO 2 absorption by carbonation throughout the service life of the PC was about 11% of the total CO 2 emissions, which is about 16% of CO 2 emissions from ordinary Portland cement (OPC) concrete.

Abstract:With the goal of reducing greenhouse gas (GHG) emissions by 26.9% below business-as-usual by 2020, the construction industry is recognized as an environmentally harmful industry because of the large quantity of consumption and waste with which it is associated, and the industry has therefore been requested to become more environmentally friendly. Concrete, a common construction material, is known to emit large amounts of environmentally hazardous waste during the processes related to its production, construction, maintenance, and demolition. To aid the concrete industry's efforts to reduce its GHG emissions, this study developed a software program that can assess GHG emissions incurred over the life cycle of a concrete product, and a case study was conducted to determine the impact of the proposed concrete assessment program on a construction project.