A BIM-Based construction and demolition waste information management system for greenhouse gas quantification and reduction

Effect of using construction and demolition waste as substrate on methane and carbon dioxide emissions from green roofs

The dairy Carbon Offset Scenario Tool (COST) was developed to explore the influence of various abatement strategies on greenhouse gas (GHG) emissions for Australian dairy farms. COST is a static spreadsheet-based tool that uses Australian GHG inventory methodologies, algorithms and emission factors to estimate carbon dioxide, methane and nitrous oxide emissions of a dairy farm system. One of the key differences between COST and other inventory-based dairy GHG emissions calculators is the ability to explore the effect of reducing total farm emissions on farm income, assuming the strategy was compliant with Kyoto rules for carbon offsets. COST provides ten abatement strategies across the four broad theme areas of diet manipulation, herd and breeding management, feedbase management and waste management. Each abatement strategy contains four sections; two sections for data entry (baseline farm data specific to the strategy explored and strategy-specific variables) and two sections for results (milk production results and GHG/economic-related results). Key sensitive variables for each strategy, identified from prior research, and prices for milk production and carbon offsets are adjusted through up/down buttons, which allows users to quickly explore the impact of these variables on farm emissions and profitability. For example, if the cost to implement an abatement strategy is doubled, what carbon offset income would be required to negate this additional cost? Results are presented as changes in carbon offset income, strategy implementation cost, additional milk production income and net farm income on a per annum and on a per GHG emissions intensity of milk production basis. COST currently contains a comprehensive range of strategies for GHG abatement, although some strategies are still in development. As new technologies or farm management practices leading to a reduction in GHG emission become available, these too will be incorporated into COST. To date, two dairy-specific abatement methodologies have been legislated as part of Australia’s commitment to reducing on-farm GHG emissions through it’s the carbon offset scheme, the Carbon Farming Initiative (CFI) and are incorporated into COST. These are the ‘Destruction of methane generated from dairy manure in covered anaerobic ponds’ and the ‘Methodology for reducing greenhouse gas emissions in milking cows through feeding dietary additives’. As an example, we explored the mitigation option Replace supplements with a source of dietary fats (reflecting the second above-mentioned CFI legislated abatement strategy) as feeding a diet higher in dietary fats has been shown to reduce enteric methane emissions per unit of feed intake. A 400 milking herd was fed a baseline diet of 2.6% dietary fat. By replacing grain with hominy meal, at a rate of 5.0 kg dry matter/ cow per day for 90 days during the 3 summer months, the summer diet fat concentration was increased to 6.4%. Enteric methane emissions were reduced by 40 tonnes of carbon dioxide equivalents (t CO 2 e) per annum for the farm. Waste methane and nitrous oxide emissions were also reduced by 0.5 and 1.6 t CO 2 e/annum, respectively. However, as reductions from these two sources of GHG emissions do not qualify for payment with this CFI methodology, their reduction could not be included as an offset income. At a carbon price of $20/ t CO 2 e, the reduction in enteric methane emissions was valued at $800/farm. The implementation cost of replacing grain with hominy was valued at $18,000/farm due to the hominy meal costing an additional $100/t dry matter compared to the grain. However, the additional milk production achieved due to the higher energy concentration of the diet resulted in an additional 70,200 litres and based on a summer milk price of $0.38/ litre, this equated to an additional income from milk valued at $26,676/farm. The overall result was a net increase in farm profit of $9,476/farm when paid on a reduction in total GHG emissions. COST can quickly allow users to ascertain the level of GHG emission reduction possible with various mitigation options and explore the sensitivity of key variables on GHG emissions and farm profitability.

BIM-based information system for econo-enviro-friendly end-of-life disposal of construction and demolition waste

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The improper disposal of construction and demolition waste (CDW) exacerbates the consumption of raw materials and emissions of greenhouse gasses. In this study, due to the high recycling rate, focusing on the meltable materials of CDW, the recycling phase of CDW is divided into four stages, namely the on-site disposal stage, the transportation stage, the reprocessing stage, and the reproduction stage. Second, based on these four stages, a carbon emission accounting model (CEAM) is established to evaluate the carbon emission benefits of meltable materials during these stages. Third, the CEAM is applied to a typical old residential area to evaluate the carbon emission reduction benefits of the CDW recycling. The results indicate that (1) the full-process carbon emissions of recycled steel, recycled flat glass, and recycled aluminum per unit mass are 677.77 kg/t, 1041.54 kg/t, and 845.39 kg/t, respectively, which are far lower than their corresponding ordinary meltable building materials (OMBMs); (2) the carbon emissions during the reproduction stage represent the primary component of carbon emissions in the MW recycling phase, accounting for 88.52% to 97.45% of the total carbon emissions; and (3) the carbon emissions generated by the recycling of cullet per unit mass are very high, reaching 1768 kg/t, which is 4.3 times that of scrap steel (409.05 kg/t) and 3.6 times that of scrap aluminum (483.76 kg/t). The research findings could provide theoretical methods and experimental data for decision-makers to formulate treatment plans for meltable materials in CDW, thereby empowering urban carbon emission reduction and promoting sustainable development. Construction parties engaged in demolition tasks should enhance on-site sorting and collaborate with recycling companies to ensure its efficient recycling. Recycling companies need to focus on high-carbon-emission stages, such as the reproduction stage, and strengthen technological research to improve carbon reduction benefits.

Better information on greenhouse gas (GHG) emissions and mitigation potential in the agricultural sector is necessary to manage these emissions and identify responses that are consistent with the food security and economic development priorities of countries. Critical activity data (what crops or livestock are managed in what way) are poor or lacking for many agricultural systems, especially in developing countries. In addition, the currently available methods for quantifying emissions and mitigation are often too expensive or complex or not sufficiently user friendly for widespread use.The purpose of this focus issue is to capture the state of the art in quantifying greenhouse gases from agricultural systems, with the goal of better understanding our current capabilities and near-term potential for improvement, with particular attention to quantification issues relevant to smallholders in developing countries. This work is timely in light of international discussions and negotiations around how agriculture should be included in efforts to reduce and adapt to climate change impacts, and considering that significant climate financing to developing countries in post-2012 agreements may be linked to their increased ability to identify and report GHG emissions (Murphy et al 2010, CCAFS 2011, FAO 2011).

Major US electric utility climate pledges have the potential to collectively reduce power sector emissions by one-third

Buildings consume 40% of raw material and primary energy and generate 35% of industrial waste worldwide, making this sector play a main role in raw material depletion, energy consumption and carbon emissions which provoke great environmental impact and worsen Global Warming. Latin American countries including Mexico have the world's highest urbanisation rate (84%) but lack effective construction and demolition waste (CDW) management to thrive in regenerative sustainability, climate change mitigation and post-pandemic economic recovery. This work applies the Spanish current model to quantify on-site 61 Mexican social housing CDW with surveys to workers and supervisors as an additional source of data. The results of the case study show that social housing consumes 1.24 t.m-2 of raw materials and produces 0.083 t.m-2 of CDW. Cement-based, ceramic and mixed CDW represent 83.44% of total CDW. When considering inert soil as a recyclable resource, 78% of the remaining CDW ends in landfills and only 22% of it goes to recycling plants. The implementation of this methodology will deliver sustainable CDW management in Mexico, by minimising CDW production, promoting related legislation and allowing replacement of current construction materials for eco-efficient ones. Furthermore, these data can broaden the Spanish coefficients of the construction resources that become CDW to build an internationally sourced database.

Construction and Demolition Waste (CDW) results in substantial environmental, economic and social losses. Alternatively, Building Information Modeling (BIM) was pointed as a promising technology to achieve zero-waste goals. Recent studies showed that BIM use for CDW Management and Assessment (CDWM/A) is still limited and needs a better understanding. This research addresses this gap through a systematic review. The study revealed that BIM disposes of 5 instruments and 6 functionalities that allow important CDW minimization and inclusion of extrinsic CDWM/A resources into an integrated environment. The paper classified 39 CDWM/A guidelines into 3 categories and examined 15 data inventories supporting the analysis of CDW plans and impacts. nD-BIM data scalability was demonstrated to ensure integration of these resources into a single model, enabling multiparametric simulations and accurate CDWM/A. Similarly, the study discloses 57 digital tools used to assist CDWM/A and develop new solutions, and other 51 to manage/assess CDW environmental impacts. BIM interoperability was confirmed to foster an inclusive environment in which tools can collaborate and operate with 19 other technologies, ensuring enhanced CDWM/A and leveraging existing wares. Accordingly, the paper introduces nD BIM-WMS, a CDWM/A system disclosing how intrinsic and extrinsic BIM environments can be interconnected to enable efficient BIM-based CDWM/A through a practical algorithm maximizing the 4R principle reward, thereby supporting balanced, well-managed, and optimized sustainability. Overall, the study affirms BIM's potential to advance zero-net waste and equips scholars and practitioners with well-founded knowledge and methodological system, paving the path for grounded research, regulation, and innovation in this field.

Construction and demolition waste management in China through the 3R principle

The Zambian Construction Industry (ZCI) is one of the fastest growing sectors in Zambia arising from increased infrastructure development. The ZCI, like elsewhere, is composed of many players including designers, contractors, regulators, manufacturers and suppliers of construction materials. The country has seen an upsurge in Construction and Demolition Waste (CDW) generation due to increased construction activities. However, opportunities for utilizing CDW for sustainable construction and management have been minimal. Most research in developing countries has focused on Municipal Waste Management (MWM) rather CDW. In Zambia, CDW is a challenge in the absence of legislation, guidelines and regulation. In the developed countries, guidelines, legislation and regulation, exist. Sustainable utilization of CDW in Zambia is limited due to inadequate policy guidelines and legislation. The research aimed at estimating the levels of CDW waste generation and utilization, and proposing a framework for sustainable utilization and management of CDW. The research required both qualitative and quantitative data. Primary data was collected through questionnaires, interviews and site visits whilst secondary data was obtained through literature review. The research, conducted in four provinces of Zambia, established that CDW generation rates were mainly in the 1-10% levels and utilization was low, regardless of the type of project. The main cause for such generation levels was poor skills and workmanship. Further, there are no specific policies dealing with CDW in Zambia. A frame work for estimating and quantifying CDW generation over the whole life cycle of a construction project is also proposed.

Municipal water and wastewater services have complicated sources of greenhouse gas (GHG) emissions, and quantifying their roles is critical for tackling global environmental challenges. In this study we provide a systematic review of the state‐of‐the‐art on GHG emission characterizations of China's urban water infrastructure with the aim of shedding light on global implications for sustainable development. We started by synthesizing a framework on GHG emissions associated with water and wastewater infrastructure. Then we analyzed the different sources of GHG emissions in drinking water and wastewater treatment systems. In drinking water services, electricity consumption is the largest source of GHG emissions. A particular concern in China is the common use of secondary pumping for high‐rise buildings. Optimized pressure management with an efficient pumping system should be prioritized. In wastewater services, non‐CO2 emissions such as methane (CH4) and nitrous oxide (N2O) emissions are substantial, but vary greatly depending on regional and technological differences. Further research directions may include GHG inventory development for urban water systems at the plant level, quantifications of GHG emissions from sewer systems, emission reduction measures via water reclamation, renewable energy recovery, energy efficiency improvement, cost–benefit analyses, and characterizations of Scope 3 emissions.This article is categorized under: Engineering Water > Sustainable Engineering of Water Science of Water > Water and Environmental Change Engineering Water > Planning Water

Alkali-activated materials (AAMs) or geopolymers have been considered for many years as a sustainable substitution for the traditional ordinary Portland cement (OPC) binder. However, their production needs energy consumption and creates carbon emissions. Since construction and demolition waste (CDW) can become precursors for manufacturing alkali-activated materials, their use as substitutes for traditional AAM (such as metakaolin, blast furnace slag, and fly ash) can solve both the problem of their disposal and the problem of sustainability. Furthermore, CDW can also be used as aggregate replacement, avoiding the exploitation of natural river sand and gravel. A new circular economy could be created based on CDW recycling, creating a new eco-friendly building practice. Unfortunately, this process is quite difficult owing to several variables that should be taken into consideration, such as the possibility of separating and sorting the CDW, the great variability of CDW composition, the cost of the mechanical and thermal treatment, the different parameters that compose an alkali-activated mix-design, and public opinion still being skeptical about the use of recycled materials in the construction sector. This review tries to describe all these aspects, summarizing the results of the most interesting studies performed on this subject. Today, thanks to a comprehensive protocol, the use of building information modeling (BIM) software and machine learning models, a large-scale reuse of CDW in the building industry appears more feasible.

In Bangladesh, the minimisation of construction and demolition waste (CDW) generation is a demanding need to alleviate the environmental burden. Various barriers limit the effective CDW management strategies in this economy. Hence, this paper aims to explore the major obstacles to managing construction and demolition waste in Bangladesh. Major barriers identified in previous studies were selected through a literature review, and a tentative question list was prepared. Afterwards, by the suggestion of four experts, a structured questionnaire was designed to collect the respondents' knowledge on CDW, impacts of CDW and 19 barriers that hinder the effective implementation of CDW management. On-site visits and face-to-face interviews were to collect research data. The results of the questionnaire survey were analysed using ranking analysis. The findings show that waste generation in construction and demolition sites is different. Primary wastes generated in demolition sites are concrete and bricks, whereas in construction sites, the percentage of concrete, timber, brick, metal, sand, etc., is high. This study also evaluated that female respondent, mainly field workers, have more knowledge about CDW management than males. However, the number of female workers is few due to socio-cultural barriers. Based on the ranking analysis, the four most significant barriers that were identified hindering the effective CDW management are: 'Negligence and carefree attitude of workers', 'Poor supervision', 'Inadequate workers' skill', 'Space lacking for on-site storage'. The current study contributes to the field by identifying and highlighting the challenges to CDW management implementation in Bangladesh and providing remedial solutions to the identified barriers. Furthermore, the results could be helpful to provide information for developing strategies to improve CDW management strategies in Bangladesh.

Nowadays, the construction, remodelling and demolition operations can cause serious environment impacts. These activities produce materials defined as construction and demolition wastes (CDW). The CDW generated in Europe represents around 25–30 % of total waste. In EU 28 CDW production is about 821,160,000 t, but there is a significant difference among the European countries, mainly because of the variation of construction and demolition activity. In 2011, the total production of CDW in Portugal was around 930,000 t, but regional production is not homogeneous. The substantial inert fraction from the CDW makes them suitable for reuse. The present study aims to quantify and characterize CDW from residential recuperation of small constructions in Portugal and then propose mitigating measures to improve CDW management. The results obtained by bibliographic research revealed that the construction and demolition activity has decreased significantly in the last years and consequently CDW production. In addition, it was observed a big number of entities were involved in CDW management. Therefore, it was necessary to select a specific area from Portugal (Setubal region) which has thirteen City Halls. The surveys had scarce response. This can be explained by the lack of obligation of enterprises with less than ten employees to register CDW production and because in some regions the CDW are mixed with municipal solid waste. Most of the CDW collected from Setubal region was disposed in landfill. In order to reduce CDW production it is necessary to promote and make available recycled materials for small works at low cost.