1- Introduction

2- Framework for resource recovery and CE into buildings

3- Study methodology

4- Results and discussion

5- Conclusions

References

Abstract

Buildings are responsible for a significant natural resources diminution and emissions to the environment. Thus, the building industry has become a global target for reducing environmental impacts and curbing resource depletion. Concerning the rapidly growth of buildings, life cycle assessment (LCA) is increasingly used for assessing and mitigating the associated environmental impacts from material selection to the whole building systems. However, many of the previous studies have focused on the impacts assessment from buildings within a restricted system boundary, especially lack of consideration of several critical factors when assessing the whole building, such as wastage level of raw materials during building construction and the disposal impacts, renovation and replacement of components of building and their treatment, and waste treatments during building demolition. As the industry is shifting from linear to circular, the consideration of those factors are essential for ensuring waste reduction, resources recovery and resource-efficient construction, not to mention about increasing the accuracy of such assessment. Therefore, the present study was conducted to assess the environmental impacts of the mentioned aspects at different life cycles of building by LCA. The results were then critically discussed after identifying the contribution of waste materials at different stages of building to the total impacts. The potential sustainable strategies for waste treatments during the construction, operation and end-of-life stages of building were then highlighted to help lay important foundation for adopting circular economy principle in the building industry and establishing benchmark for future reduction.

Introduction

The construction industry is one of the main contributors to environmental burdens, consuming significant amount of non-renewable bulk resources and raw materials, and causing considerable waste streams (Faleschini et al., 2016). While the industry plays an important role for economic contribution and social development throughout the world (Vitale et al., 2017), the industry also contributes to about 40% of depletion of natural resources, 18% of greenhouse gas emissions, and 25% of wastes globally (Teh et al., 2018). The building sector consumes a substantial amount of resources and is, therefore, one of the largest contributors towards environmental impacts (Atmaca, 2016; de Klijn-Chevalerias and Javed, 2017). For example, buildings are responsible for about 40% of the total energy consumption and 36% of the total CO2 emissions worldwide (Pal et al., 2017). Therefore, increasing attention has been devoted in the building sector to minimize the environmental impacts globally (Hossain and Poon, 2018a). In addition to the selection of low impact, sustainable and durable materials, consideration of sustainable management of construction and demolition (C&D) waste is also important to minimizing the disposal problem and reducing the associated environmental burdens, as a huge amount of land is currently occupied for the disposal of those materials, leading to an increase in the ecological footprint of the sector (Faleschini et al., 2016). Due to the volume, nature and high recycling potential, C&D waste is a priority waste stream in many part of the world including the European Union (EU) (Vitale et al., 2017; Borghi et al., 2018). Because C&D waste puts huge pressure on depleting landfills and affects the environment adversely (Butera et al., 2015; Bovea and Powell, 2016; Akinade et al., 2018), it is important to improve the sustainability by adopting design solutions with the aim to optimize resource usage and minimize waste material generation, as restated in the EU action plan for a circular economy (CE) (Vitale et al., 2017). Therefore, further policies and strategies are needed for resource-efficient management of C&D waste as the current trends are to the landfill or downcycling practices (Di Maria et al., 2018), and thus, EU proposed a new framework for this waste in the CE package (GálvezMartos et al., 2018).

In-situ gasification chemical looping combustion (iG-CLC), which has been tested on pilot plant level, is regarded as an advanced carbon capture and storage (CCS) technology for reducing CO2 emissions. A life cycle global warming impact (GWI) analysis is performed to consider the lifetime emissions of the lowcarbon iG-CLC technology. Herein, the capacity is considered to be 610 MWe using natural ilmenite as oxygen carrier and steam as gasification agent. At the condition of operational pressure of 15 atm and air reactor temperature of 1050
C, the net power efficiency of 37.7% for achieving 93.5% inherent CO2 capture is obtained in simulations with thermodynamically optimum condition. The life cycle GWI is calculated equal to be 160.3 kg CO2-equivalent/MW h. The effects of several essential parameters, including steam to carbon ratio (S/C), oxygen carrier to fuel ratio (ф), different oxygen carriers and lifetime of oxygen carriers, on the lifecycle GWI have been analyzed and discussed to meet the potential possibility for further reducing greenhouse gas (GHG) emissions. To obtain sufficient carbon capture efficiency, the S/C ratio and ф are suggested to be 1.3 and 1.2 in this study, respectively. The life cycle GWI is heavily dependent on lifetime of ferrum (Fe) when it is less than 2000 h, beyond that range, the GWI is decreasing, but very slowly.

Introduction

Increasing concerns associated with irreversible climate change have led policy-makers to design climate policies to reduce the anthropogenic Greenhouse gas (GHG) emissions. For example, the Chinese government committed to reduce its CO2 emissions per unit of GDP by 40%e45% of 2005 levels by 2020 (Yi et al., 2011). Significant R&D efforts are underway worldwide to mitigate GHG emissions, including (1) switching to low-carbon fossil fuels, such as biofuels, natural gas or hydrogen; (2) decarbonisation of fuel or flue gas and then carbon sequestration, i.e. carbon capture and storage (CCS); (3) accelerating the use of renewable energy (such as bioenergy, direct solar and wind energy). The share of low-carbon electricity supply (including renewable energy, nuclear and CCS) is expected to be increased from currently 30% (2014) to more than 80% by 2050 (IPCC, 2014). Yet still in a very early stage of technical demonstration, the cost of renewable energy is not currently competitive; the current CCS technology incorporating into a power plant has also not reached large-scale commercial maturity owing to the efficiency losses (e.g. CO2 capture by amine scrubbing reduces the power output by 20e30% for a typical coal-fired power plant) as well as cost enhancement on CCS. Though numerous power plants can be incorporated with CCS activity, very limited demonstration plants have gained any measure of acceptance from an industrial viewpoint as more than 20 large-scale CCS projects have been cancelled in 2010e2016 owing to the sharply fluctuated policy and financial support (IEA, 2016). Up-to-date information related to CCS can be found elsewhere (Boot-Handford et al., 2014; Macdowell et al., 2010).

مقاله سال 2016

برای بهبود قابلیت اجرای ارزیابی چرخه زندگی (LCA) در پشتیبانی تصمیم گیری قوی و مستقیم ، یک روش یکپارچه از طریق ترکیب روش های تحلیل عدم اطمینان و تحقیق در عملیات در یک چارچوب عمومی LCA گسترش یافت. این روش می تواند (a) به ارزیابی جامع تاثیرات زیست محیطی در سطوح خدمت-محصول متعدد کمک کند ، (b) انعکاس عدم اطمینان های مربوط به LCA متعدد را تسهیل کرده و آنها را در فرآیند تصمیم گیری تبعی منتقل می کند، و (c) طرح های تخصیص آب مطلوب را برای به حداقل رساندن تاثیرات زیست محیطی چرخه زندگی شناسایی می کند. این کار موجب ارتقا روش LCA مرسوم و همچنین تخصیص منابع آب می شود. سپس این روش در شهری که دارای مشکل آب بود (یعنی شهر Dalian)، شمال غربی چین مورد بررسی قرار گرفت. این کاربرد نشان داد که روش مطرح شده در تولید طرح های عرضه آب مطلوب ، انعکاس تاثیرات زیست محیطی چرخه زندگی مربوطه و تقویت قابلیت های روش های تحقیق در عملیات و LCA موثر بود. نتایج همچنین نشان دادند که سه مشارکت کننده اصلی در تاثیرات زیست محیطی چرخه زندگی بخش های Pulandian و Zhuanghe و منطقه شهرداری شهر هستند.