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A comparative life cycle study of alternative materials for Australian multi-storey apartment building frame constructions: Environmental and economic perspective

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Abstract

The building construction sector contributes to a quarter of the total Australian Greenhouse gas emissions. These emissions are mainly attributed to the use of energy intensive materials. To achieve better environmental benefits and cost saving, the utilisation of wood-based construction materials is currently attracting attention. However, the manufacturing of engineered wood products consumes large quantities of chemicals and energy, which may have adverse environmental impacts. Therefore, a life cycle study was conducted to compare various materials for constructing the structural frame of a 4-storey apartment building compliant with the Australian building codes. Five alternatives were assessed: Laminated Veneer Lumber (LVL) manufactured from early to mid-rotation hardwood plantation logs (LVLm), LVL manufactured from mature hardwood plantations (LVLh), LVL manufactured from mature softwood plantations (LVLs), concrete and steel. The functional unit was defined as the whole building structural frame. Global Warming Potential (GWP), Acidification, Eutrophication, Fossil Depletion, Human-toxicity Potential (HTP) and Life Cycle Cost (LCC) were evaluated. The LVL generally performed better than concrete and steel structural products. Particularly, LVLm had the lowest GWP (2.84E4±233 kg-CO2-eq) and LCC ($128,855 ± 2797), which were less than a quarter of the concrete option. However, the usage of chemical preservatives and phenol-formaldehyde adhesive during the LVL production and treatment caused the HTP impact to be higher than the steel option. Monte Carlo Analysis showed that while the LVL options presented a higher sensitivity to the combined uncertainties, the overall ranking of the five options remained the same. Therefore, the inclusion of wood-based material in structural elements may significantly contribute to reduce the environmental impacts and the LCC of the construction sector.

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... Val and Stewart [6] have used the LCC method to justify the use of stainless steel in reinforced concrete structures due to its corrosion-resistance feature. In their study, Lu et al. [7] have calculated environmental pollution and the cost of the materials used in multi-storey Australian apartments for five alternatives. Furthermore, the social dimension was discussed in numerous studies. ...
... Results comparison Various comparative studies of steel and concrete buildings aimed to calculate the pollution of the two products in different impact factors. After reviewing them, it could be claimed that the environmental results of this study are compatible with most of those concluding that a concrete building creates more pollution [7,11,14,36]. As far as the economic dimension is concerned, few comparative LCC studies among the two types of frames have indicated quite different outcomes compared to this study. ...
... For example, [11] showed that building with a combination of concrete materials inside their structure costs more than its steel equivalents. In addition, [7,36] concluded that the total costs of concrete structures, considering all of the life cycle stages, were higher than those of steel structures. These contradictions between the current study and aforementioned papers have one major justification: the cheap price of cement in Iran. ...
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As one of the most prominent industries in developed and developing countries, the construction industry has had substantial impacts on different aspects of the environment, society, and economy. In recent years, sustainable construction has been introduced as an approach to evaluate the various construction phases based on environmental, economic, and social dimensions, also known as the triple bottom line (TBL). To conduct a sustainability analysis of the buildings in Tehran, the capital city of Iran, two conventional construction frames were selected, namely steel frame and concrete frame. In this research, three conventional approaches for the evaluation of the TBL, namely the life cycle assessment (LCA), life cycle cost (LCC), and social life cycle assessment (SLCA), were, respectively, used for the study of environmental, economic, and social impacts. The main results of the study are summarized as the following: Overall, based on the LCA results, the concrete frame led to almost 38% more environmental pollution than steel frame. In terms of the total prices of the buildings, considering their LCC and with respect to the present value (PV) method, the steel frame was almost 152,000 USD more expensive than the concrete frame. The quantified results of the social dimension by the SLCA method showed that concrete and steel buildings had a score of 0.199 and 0.189, respectively, which indicates that concrete had a slightly better social performance based on expert opinions. A multi-criteria assessment and sensitivity analysis of the results were conducted by a graphical tool, namely the mixing triangle, and showed that the overall preference of each alternative depends mainly on the importance weights given to each aspect of the assessment. However, one of the main findings of the research was that overall, giving a high importance weight to environmental dimension leads to sustainability preference of steel over concrete frame, while giving high importance weights to economic or social dimensions leads to sustainability preference of concrete over steel frame. Findings of the study are beneficial to decision-makers in the construction industry since they can decide on the best alternative among concrete and steel frames based on their strategies.
... Recent studies comparing CLT and reinforced concrete in Australia have shown that the LCC of CLT is 1.3% cheaper than conventional reinforced concrete in mid-rise residential buildings (Jayalath et al., 2020). Lu et al. (2017) also found that the LCC of the concrete frame of apartment buildings was about 10% lower than similar building using steel during the construction stage. Thomas and Ding (2018) adds that material and construction cost make up to 84% of the LCC in residential buildings. ...
... The ISO15686-5 is the LCC standard for the building and construction sector. In Australia and the AS/NZS4536:1999 provides useful guidelines in conducting LCC in buildings (Lu et al., 2017). Nevertheless, the application of LCC in buildings is challenging as the method relies on a wide range of assumptions (Zuo et al., 2017). ...
... The LCC in this study also utilised data based on the project documents, and supplemented information from relevant literature such as Lu et al. (2017) and Jayalath et al. (2020). The system boundaries for the LCC aligns with the LCA conducted in order to achieve consistency (Valdivia et al., 2021). ...
Article
Significant transition in the built environment will require an integrative and holistic application of Life Cycle Sustainability Assessment (LCSA) to accomplish a better understanding of shift in sustainability impacts across building life cycle phases. Nevertheless, there has been considerable difficulty in implementing life cycle sustainability thinking in buildings due to the complexity of harmonising the three dimensions of LCSA. This work, therefore, aims to monetise the key life cycle sustainability impacts of reinforced concrete and cross laminated timber (CLT) on a building project. This research undertakes a LCSA study based on cradle-to-gate system boundary to evaluate two alternative structural systems in an equivalent 5-star GreenStar-rated public infrastructure building project in Victoria, Australia. Hotspot analyses is conducted to ensure that indicators considered in the study represents up to 85% of the key life cycle impacts. Obtained results show that the overall life cycle sustainability impact of the original structural system ($ 3.02 million) reduced by more than half (i.e., 51%) by adopting the modified-CLT structural system ($1.55 million) in the case study project. Material substitution in building structural systems could provide a viable pathway in achieving net-zero emissions in Australia's built environment. Consequently, there is a compelling case to develop a holistic life cycle sustainability rating tool to enhance integrated design practice, improve resource utilisation and foster transparency in achieving life cycle sustainability in the built environment.
... Despite the high number of publications and recent developments in the standardization of LCA and LCC, very few studies mention any standards as a basis for their calculations. For the LCA process, ISO 14040, ISO 14044, the building-specific EN 15978, or the building-product-specific EN 15804 are referred to [6,8,52,56,57,59,62,63,65,66,72]. Only three studies refer to an LCC standard; two Australian studies [52,56] refer to AS/NZS 4536, while one European study [62] refers to EN 15686-5. ...
... For the LCA process, ISO 14040, ISO 14044, the building-specific EN 15978, or the building-product-specific EN 15804 are referred to [6,8,52,56,57,59,62,63,65,66,72]. Only three studies refer to an LCC standard; two Australian studies [52,56] refer to AS/NZS 4536, while one European study [62] refers to EN 15686-5. Moreover, underlying calculation metrics were rarely clearly described and are often missing altogether, making results difficult to interpret. ...
... Conci et al. [45] assume a linear decrease in electricity mix emissions over time and a 30% increase in manufacturing efficiency over the next 100 years. Two studies apply discounting to environmental impacts after converting them to monetary values: for GWP only [56], or for a set of indicators [70]. One study considers a price increase for GWP [53]. ...
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With increasing environmental damage and decreasing resource availability, sustainability assessment in the building sector is gaining momentum. A literature review shows that the related methods for environmental and economic performance, Life Cycle Assessment (LCA) and Life Cycle Costing (LCC), show great potential for answering a multitude of questions related to building performance. Prevalent topics are the implications of LCA and LCC for retrofit solutions and the trade-offs between environmental and economic considerations in building design. A detailed review of 30 case studies shows the range of differing result integration methods and sheds light on the use of monetary valuation of environmental indicators for an integrated assessment. While a quasi-dynamic approach, accounting for the changing value of money over time, is common in LCC, such an approach is largely absent from LCA. The analysis of common metrics shows that the studies employ strongly differing system boundaries and input parameters. Moreover, a clear description of the methodological framework is missing in most studies. Therefore, this research develops an “Eco2” framework, integrating LCA and LCC for application in building design. Potential further developments for Eco2 building assessment are related to extending the system boundaries by including mechanical systems and end-of-life phases, data collection and structuring, and streamlining the approach for continuous application to all stages of building design processes. Additionally, the influence on design decisions of employing temporal parameters in both LCA and LCC and of choosing particular result integration methods should be investigated further.
... For example, thinned logs from hardwood plantations which has poor mechanical qualities can be turned into engineered wood products Kasal et al., 2015). These products may be used to substitute conventional construction materials and may contribute to lowering the environmental impacts of the building industry and contribute economical value to the forestry industry ( Lu et al. (2017b)). Hence, in order to find an optimal utilisation of the available resource to minimise the life cycle cost and the environmental burdens, all possible application pathways should be considered. ...
... A number of options were investigated to add values to this resource stream, including multiple pathways for the recovery of their energy value and use to manufacture structural components (e.g. Lu and El Hanandeh, 2016a;Lu and El Hanandeh, 2017;Lu et al., 2017b). The following sections present brief summary of each of the utilisation options considered in this model. ...
... Due to the significant amount of energy intensive materials (i.e. concrete and steel) which is being used, the Australian building construction sector contributes approximately 25% of the total national GHG emissions (Lu et al., 2017b). Recently, engineered wood products have gained great successes in the construction sector and they are quickly being recognised as a sustainable and cost-competitive building material (Bribi an et al., 2011;Kasal et al., 2015). ...
Article
Forestry products have multiple uses including energy conversion and structural elements manufacturing. Each utilisation pathway has its own environmental and economic burdens and benefits, which may also change overtime due to market demand, policy change and local environmental conditions. In this study, an optimisation framework is introduced to identify the optimal allocation of resources based on life cycle perspective. The problem is broken into a series of multi-objective linear programs to account for potential non-linearity in the objective functions and constraints. First, life cycle costing analysis and environmental life cycle assessment were conducted to quantify the environmental and economic values of each decision variable. The values were used to construct economic and environmental objective functions. Then, normalisation procedures were followed to convert the two objective functions into a single objective function. The model was applied to the case of logs generated from the second thinning of the hardwood plantations in Australia. Eight utilisation scenarios were considered, including two engineered wood products and six bioenergy applications. The costs of the displaced products by the alternatives were included as avoided costs in line with the LCA scope. The model was solved in six time periods (ten years each). The robustness of the solution was tested by assigning different weightings to the environmental and economic objectives. The result showed that Woodchips Gasification (WCG) for electricity and heat production was the dominating solution for the first period with 85% of the logs allocated to this option. Nevertheless, the quantities allocated to energy production declined progressively over the subsequent periods. The laminated veneer lumber (LVL) option surpassed the WCG and became more dominant option starting from the fourth period. In the final period, 100% of thinned logs were allocated to the LVL option due to the predicted increased demand. The developed framework offers forestry managements the foresight to enhance their long-term environmental and economic performance through strategic multi-period optimisation approach, thus avoiding the technology lock-in and allowing flexibility in the system to adapt to future changes. Although this model was demonstrated using the forestry industry case, the framework can be applied to any resource allocation problem.
... The integration of renewable technologies, reduction of environmental impacts, and low carbon materials and technologies in the construction sector have become the main target in many countries around the world [1]. Based on the literature, wood-based materials can achieve efficient environmental and economic benefits [2]. Most previous studies have compared engineering wood, such as cross-laminated timber (CLT), with concrete and steel structures [3,4]. ...
... Many studies have compared wood-based materials with other construction materials, such as concrete [8]. However, there are few studies that compare the LCA of different wood materials as a construction material [2]. compared wood-based materials with concrete and steel for residential buildings. ...
... Carbon footprint is defined as "the total amount of carbon dioxide emission, directly and indirectly, caused by an activity or that is accumulated over a product lifetime" [44]. Other environment criteria are namely: Ozone layer depletion (OLD), Terrestrial Ecotoxicity (TE), Human-Toxicity Potential (HTP), Fossil Depletion Potential (FDP) and Land use potential (LUP) were evaluated [2]. In Malaysia, the electricity consumed in producing materials such as engineering wood is considered as fossil fuel consumption, and apportioned as 96.63% of the national electricity produced in 2019. ...
Article
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The environmental emissions and energy from construction activity and building materials contributes significantly to a building's sustainability. Previous research dealing with wood or engineering wood's energy requirements compared to reinforced concrete and steel structures has shown that embodied energy and embodied carbon is significantly lower in wood-based construction. This study has assessed the environmental impact and costs of glued laminated timber (GLT) or cross-laminated timber (CLT). Hardwood and softwood variants of both GLT and CLT were considered. We compared the life cycle costs (LCC) of these alternatives to discover the lowest cost. The comparative results indicated that GLT has higher emissions in Global warming potential (GWP), Terrestrial Ecotoxicity (TE), Land Use (LUP), and Ozone layer depletion (OLD), while CLT has higher impact in Human-Toxicity Potential (HTP), Fossil Depletion Potential (FDP). The results indicated that using CLT significantly reduces embodied energy by 40%. However, a comparison of costs showed that CLT is 7% more expensive than GLT. Establishing which material performs best based on environmental and economic criteria thus required further analysis. Thus, the multi-criteria decision making (MCDM) method was applied. This showed that CLT manufactured with softwood is the most sustainable choice among the alternatives considered. This study's findings are important for aggregate level decision making of different wood materials for residential buildings.
... Thus, it becomes essential to study the environmental effects of concrete and steel frames. In a research on three construction frames (concrete, steel and wood), the environmental effects and economic analyses of each frame were carried out [11]. In their study of two office buildings, one with a concrete construction frame and the other with a steel frame, Guggemos and Horvath [8] assessed greenhouse gas emissions and energy consumption. ...
... Gervasio [24] has listed five scenarios for a building's EoL: three scenarios including landfill, recycling, and reusing steel construction as well as two scenarios of recycling and landfill of concrete structure. In this phase, 100% of the steel scrap recovered after the demotion of the steel building has been considered as recyclable, while 85% of the steel rebar used in the concrete building has been deemed recyclable, whereas all concrete residues were landfilled [11]. Since the life span of the two buildings in this study is 50 years, it is apparent that after this period and their demolition, steel scraps and concrete chunks will be the outcome of the operation. ...
... In other research, various parameters have been taken into account in order to analyze such impact. Factors including global warming potential, human toxicity potential, eutrophication, fossil fuels depletion, and acidification have been considered for impact assessment [11,26,27]. In this research, as shown in Figure 6, the impact of the global warming potential for a period of 100 years, acidification, eutrophication potential, human toxicity (considering cancer and non-cancer effects), and resource depletion (water, minerals, and renewable resources) as well as climate change, fossil fuel depletion, and ecotoxicity were assessed. ...
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Given the fact that during the recent years the majority of buildings in Iran have been constructed either on steel or concrete frames, it is essential to investigate the environmental impacts of materials used in such constructions. For this purpose, two multi-story residential buildings in Tehran with a similar function have been considered in this study. One building was constructed with a steel frame and the other was constructed with a concrete frame. Using the life cycle assessment tool, a complete analysis of all the stages of a building’s life cycle from raw material acquisition to demolition and recycling of wastes was carried out. In this research, the environmental impacts included global warming potential in 100 years, acidification, eutrophication potential, human toxicity (cancer and non-cancer effects), resource depletion (water and mineral), climate change, fossil fuel consumption, air acidification and biotoxicity. It could be concluded from the results that the total pollution of the concrete frame in all eleven aforementioned impact factors was almost 219,000 tonnes higher than that of the steel frame. Moreover, based on the results, the concrete frame had poorer performance in all but one impact factor. With respect to global warming potential, the findings indicated there were two types of organic and non-organic gases that had an impact on global warming. Among non-organic emissions, CO2 had the biggest contribution to global warming potential, while among organic emissions, methane was the top contributor. These findings suggest the use of steel frames in the building industry in Iran to prevent further environmental damage; however, in the future, more research studies in this area are needed to completely investigate all aspects of decision on the choice of building frames, including economic and social aspects.
... Other research has focused on LVL as a building material. For instance, Lu et al. (2017a) used LCA to study LVL, steel, and concrete. Their results showed that LVL performed better than steel and concrete as a structural material. ...
... Nevertheless, there are no studies that identify the differences between GLT and LVL. Most studies compare different mass timber materials such as LVL and GLT with alternatives (such as steel and concrete) to highlight mass timber as the best choice with a lower environmental impact (Lu et al. 2017a;Andersen et al. 2022;Chen et al. 2022b;Teh et al., 2017). Other research is not comprehensive, being limited to embodied energy (Ramage et al. 2017). ...
Article
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The embodied carbon of building materials and the energy consumed during construction have a significant impact on the environmental credentials of buildings. The structural systems of a building present opportunities to reduce environmental emissions and energy. In this regard, mass timber materials have considerable potential as sustainable materials over other alternatives such as steel and concrete. The aim of this investigation was to compare the environment impact, energy consumption, and life cycle cost (LCC) of different wood-based materials in identical single-story residential buildings. The materials compared are laminated veneer lumber (LVL) and glued laminated timber (GLT). GLT has less global warming potential (GWP), ozone layer depletion (OLD), and land use (LU), respectively, by 29%, 37%, and 35% than LVL. Conversely, LVL generally has lower terrestrial acidification potential (TAP), human toxicity potential (HTP), and fossil depletion potential (FDP), respectively, by 30%, 17%, and 27%. The comparative outcomes revealed that using LVL reduces embodied energy by 41%. To identify which of these materials is the best alternative, various environmental categories, embodied energy, and cost criteria require further analysis. Therefore, the multi-criteria decision-making (MCDM) method has been applied to enable robust decision-making. The outcome showed that LVL manufacturing using softwood presents the most sustainable choice. These research findings contribute to the body of knowledge about the use of mass timber in construction.
... 16 The paving units can be used in low-traffic buildings and pedestrian walkways. 17 Optimum sawdust content of 10% is recommended with 90 curing days. 18 Preferable order of curing media: water > laterite > alkaline > acid. ...
... 76 The green waste materials remains a green-field with enormous 77 environmental benefits as shown in Table 1 [16] (Danso, 2013). In addition, re-engineering of their prop-91 erties is required to mitigate their natural defects for construction 92 applications [17]. 93 Previous studies have shown that sawdust concrete and later- 94 ized concrete improved fire resistance, enhanced durability and 95 shrinkage reduction and improved cracking and spalling resistance 96 [7,18]. ...
Article
Our research produced ultra-lightweight green interlocking paving units through combined usage of sawdust and laterite as partial cement and fine aggregate replacements respectively. Interlocking paving units, water-cured for 90 days at optimum 10% sawdust content, achieved compressive strength of 16.6 MPa and skid resistance of 64.5 PVT, which exceeded the minimum requirements of 3.45–15 MPa and 45PVT respectively. The developed ANN model was classified as very good in terms of prediction efficiency of compressive strength (CS) and skid resistance for different curing media based on Nash & Sutcliffe criterion of efficiency (NSE). However, the prediction efficiency for CS was better than SR in terms of NSE, root-mean-square error (RMSE) and mean-square error (MSE), and was able to capture the interactive effects of considered factors. In line with ANN results, CS and SR increased with curing age but decreased with increasing sawdust content. In terms of durability performance and compressive strength development, the preferable order of curing media is water > laterite > alkaline > acid. Multi-criteria evaluation of ANN models is recommended for better interpretation of model efficiency.
... The results of that study identified problems in the application of LCC methodology in UA such as the frequent not inclusion of essential costs such as operational labour and infrastructure intro the cost calculation. According to Lu et al. (2017), the exclusion of the labour identified as the most significant operation cost and an important production factor (Baumgartner and Belevi, 2001) was the main reason for the incomplete LCC analysis in many UA studies (Lu et al., 2017). Regarding, the infrastructure cost (e.g., greenhouse structure), its inclusion in the LCC is crucial for future development of UA in cities, especially for boost the implementation of innovative environmentally friendly UA systems on a large scale. ...
... The results of that study identified problems in the application of LCC methodology in UA such as the frequent not inclusion of essential costs such as operational labour and infrastructure intro the cost calculation. According to Lu et al. (2017), the exclusion of the labour identified as the most significant operation cost and an important production factor (Baumgartner and Belevi, 2001) was the main reason for the incomplete LCC analysis in many UA studies (Lu et al., 2017). Regarding, the infrastructure cost (e.g., greenhouse structure), its inclusion in the LCC is crucial for future development of UA in cities, especially for boost the implementation of innovative environmentally friendly UA systems on a large scale. ...
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The construction of innovative urban agriculture systems in cities has increased due to food and environmental concerns. While the environmental performance of urban agriculture has been extensively studied, research on the life cycle costs urban agriculture systems is still limited, which constraints sustainability-oriented decision-making processes. This paper analyses the economic viability of tomato production cycle in an innovative building with an integrated urban agriculture system in rooftop by applying the life cycle cost methodology. The data was collected from direct measurements and internal and external sources. To calculate labour costs, a customised data collection sheet was created. The results are presented by life cycle stage, cost category and type of cost (fixed & variable). Results indicate that the main cost drivers for tomato production are labour (24.7%), the rooftop greenhouse structure (15%), the external pest control (12.6%), and rainwater consumption (9.5%), accounting altogether for 61.8% of the total costs. Accordingly, cost reduction solutions are evaluated through the development of sensitivity scenarios (rooftop greenhouse structure design, tap water use and rainwater tank size), including the consideration of another relevant aspect, such as the role of the production level output, as it can greatly influence the economic viability and profitability. Finally, the main environmental and social aspects of these urban production systems are also included.
... Materials with a high residual value because of their scarcity or energy-intensive production, such as metals, should also receive financial credits in LCC. However, these credits (e.g., for scrap metal) can be very small compared to investment cost [33], and they happen in the distant future. Moreover, in the databases used for this study, disposal costs include potential material values but do not consider them separately, i.e., if there are economic benefits for phase D, they are merged with the demolition and disposal cost. ...
... In all scenarios, the inclusion or exclusion of end-of-life credits has a significant impact, especially on options with large amounts of wood or metals. This is in line with results from the literature suggesting that wood and steel options are more sensitive towards changes in discount rates due to significant credits in the end-of-life phases [33]. ...
Article
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The architecture, engineering and construction (AEC) sector has great potential and responsibility for reducing its considerable resource consumption and high share of global emissions.However, economic factors are often cited as barriers to more environmentally friendly solutions inbuilding design. Hence, environmental and economic life cycle assessment (LCA and LCC) are of utmost importance in building design. They serve as the base methodologies for what we call the“Eco2” framework. In this context, monetary valuation of multiple environmental impacts allows to integrate the results as a basis for design decisions. A case study representative of small-scale office buildings in Germany illustrates the Eco2 framework and shows the influence of temporal parameters (discount rates and price changes), as well as of differing monetary valuation, on the ranking of design options. Varying the temporal parameters affects the ranking of different solutions for the structure and finishes of the case study building but not for its mechanical, electrical and plumbing(MEP) systems and operation. However, the ratio of environmental life cycle cost (eLCC) to financial life cycle cost (fLCC) is significantly higher for MEP systems and operation than for the structure and finishes. This investigation shows that it is possible to achieve simultaneous emission and cost savings, whereas temporal factors can decisively influence decision making in design processes.
... One strategy to decrease the climate impact is to use a material with less climate impact instead of the conventional concrete. Engineered wood products (EWPs) such as cross-laminated timber (CLT) and laminated veneer lumber (LVL) have proven to be a successful alternative (Börjesson and Gustavsson 2000, Nässén et al. 2012, Guo et al. 2017, Lu et al. 2017, Mantanis et al. 2018). The selection of insulation material has also proven important in order to reduce the climate impact (Liljenström et al. 2015) and in this application as well, replacing glass wool, polystyrene, polyurethane, or rock wool by wood-based insulation material has been shown to have the potential to decrease the climate impact (Schiavoni et al. 2016, Hill et al. 2018. ...
... LCC-studies indicate that, when constructing multi-storey residential buildings in the Nordic countries, there are small differences in price between buildings with wooden frames and buildings with concrete frames (Eriksson 1995, Gustafsson 1998, Nässén et al. 2012, Pal et al. 2017. Studies in other countries indicate that construction with timber could be up to three times cheaper (Hossaini et al. 2015, Lu et al. 2017. One important barrier for the selection of wood products is the perception that wood products involve higher costs due to a more frequent maintenance and/or shorter life cycles (Riala and Ilola 2014). ...
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Many studies have shown that wooden buildings in general have a lower climate impact than buildings built of conventional materials such as concrete and steel. In Sweden, however, only about 10% of the multi-dwelling buildings are built with timber frames. The goal of this empirical study is to provide a broad picture of the views of Swedish actors regarding the use of wood products in multi-storey residential buildings and suggest measures for an increased use. A questionnaire concerning the use of wood products in construction was sent out to Swedish developers, main contractors, and architects and 100 answers were received. The study shows that the views of the groups of actors differ in some respects and factors that may either facilitate or be obstacles to an increased use of wood products were identified and discussed.
... However, some authors strongly recommended the inclusion of labour costs at the operation stage. For example, Woodward (1997) classified labour as the main operation cost, while Lu et al. (2017) stated that labour costs were an important factor and that its exclusion was the main reason for the incomplete LCC analyses in some studies. Finally, Sanyé-Mengual et al. (2015a) also demonstrated that labour was the most significant operation cost when analysing the economic performance of a rooftop greenhouse (RTG) in Barcelona. ...
... Given that the lack of information is a recurrent reason for not including costs, we suggest future research to consider both maintenance and end-of-life costs for more complete LCC for UA. This is primarily because Lu et al. (2017) explained that disposal and demolition costs, as well as labour costs, are important factors and that their not inclusion is the main reason for insufficient LCC analysis. As for the maintenance costs, we presume that the importance of these costs will increase in the future because of their dependency on construction costs. ...
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Purpose The aim of this research is to carry out a literature review of the use of life cycle costing (LCC) in the urban agriculture (UA) sector by analysing its evolution over a 22-year period from its beginning in 1996 to July 2018. Methods A total of 442 references were obtained from two principal databases, Scopus and Web of Science (WoS). After a long refining process, 20 (4.5%) references containing the keywords LCC and UA were selected for analysis. Then, we classified and organized the selected references in 4 groups. Qualitative methods were used for analysis, and results on general characteristics of the 20 references and by each group were elaborated. Lastly, we discussed and concluded the most significant findings. Limitations and future research were also included. Results and discussion Our major findings were as follows: (i) urban horticulture was the most studied urban agriculture practice among studies that used LCC for UA; (ii) LCC plays a secondary role in its integration with LCA; (iii) only 4 of the10 papers in group 1 used additional financial tools; (iv) very few (3) papers appropriately applied the four main LCC stages; and on the other side, essential costs like infrastructure, labour, maintenance, and end-of-life were frequently not included. Conclusions Since we found that life cycle assessment (LCA) was the predominant methodology, we suggest that future research apply both LCA and LCC analyses at the same level. The LCC analysis was quite incomplete in terms of the costs included in each LCC stage. We recommend that the costs at the initial or construction stage be considered a necessity in future studies in order to implement these new systems on a large scale. Due to the limited use of labour cost at the operation stage, we also suggest that labour be included as an essential part of the urban production process. Finally, for more complete LCC analysis for UA, we recommend (i) that all LCC stages be considered and (ii) that additional financial tools, such as net present value (NPV), internal rate of return (IRR) and payback period (PBP), be used to complement the LCC analysis.
... Other studies have been proposing the integration of several parameters to evaluate building energy use. Most of them take into account environmental or energy parameters along with economic ones [13][14][15][16][17][18] and, seldom, some social criteria [19][20][21]. Mikučionienė et al. [20,22] considered the inclusion of energy efficiency measures based on sustainability criteria in their research, and they defend the use of quantitative and qualitative evaluation. ...
Article
The main goal of this research is the proposal of an integrated approach, considering sustainability indicators related to energy life cycle of the building, for evaluation of energy efficiency measures with adaptation to climate change in Brazilian social housing projects. A Sustainability Index in the Energy Life Cycle was proposed that includes environmental, energy, economic and user thermal comfort indicators. A case study applied in the city of São Paulo, considered a representative project of the sector and cases with energy efficiency adaptation measures for three climate scenarios, considering climate change. The integrated approach highlighted the importance of the initial selection of materials, considering their associated impacts as well as the thermal and energy performance of the building during its life time, and the importance of climate change for the operational phase of the building. With the Sustainability Index in the Energy Life Cycle, large reductions were obtained comparing cases with adaptation measures to current practice. Results of this research contribute to improve project’s decisions with the incorporation of a holistic approach for the projects that are being produced for the housing deficit, considering better energy performance and lower resource consumption for users and the country in the long term.
... Timber is generally acknowledged as one of the most effective building materials in terms of environmental sustainability because of its inherent eco-compatibility, mechanical and building physic performance, and ease to install [1][2][3]. In the literature, there are numerous studies aimed at evaluating, through Life Cycle Assessment (LCA) approaches, the environmental impact of timber constructions in relation to other materials, especially concrete and steel, with reference to the consumption of raw materials and primary energy, the production of carbon dioxide, and in general the emission of greenhouse gases (GHG) in all phases of the useful life of the material [4][5][6][7][8][9][10][11][12][13][14][15]. The general result is the lower level of environmental impact of timber, especially considering wood carbon storage capacity. ...
Article
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Timber buildings are experiencing a rapid diffusion due to their good performance and their sustainability; however, some steps of structural timber production process, such as drying, are energy-intensive and environmentally impactful, and many wood species are also affected by low yield. Therefore, it would be important to determine the quality of the green material, that is, in wet condition, before undergoing the most impactful and expensive production steps. This paper describes a research aimed at quantifying the variation of the dynamic modulus of elasticity MoEdyn, which is commonly used for structural timber mechanical grading, from wet to dry condition in Sardinian maritime pine boards to be used for the production of laminated timber, and to examine the relationship between wet and dry MoEdyn. The MoEdyn was determined from measurements of the velocity of sonic waves propagating through the boards. The results show that the dry MoEdyn can be estimated starting from boards sonic testing in the wet condition, so providing a basis for implementing Sardinian maritime pine pre-grading in order to obtain the reduction of manufacturing costs, the abatement of environmental impact, and the increase of structural grade yield.
... All these aspects favourably affect the abatement and minimization of costs, as well as the environmental impact. There are numerous studies aimed at evaluating, through LCA approaches, the environmental impact of timber constructions in relation to other materials, especially concrete and steel, with reference to the consumption of raw materials and primary energy, to the production of carbon dioxide and in general to the emission of greenhouse gases in all phases of the useful life of the material [7][8][9][10][11][12][13][14][15][16][17][18]. The general result is the lower level of environmental impact of timber, especially considering the carbon dioxide storage capacity of the wood. ...
Chapter
This paper illustrates the potential of using wood as a structural material in terms of sustainable construction and analyses the opportunities offered by the plant of production processes based on the use of locally-grown wood to the end of promoting the development of sustainable economies in narrow and interconnected communities like those of the islands. In detail, the convenience of planting in Sardinia a supply chain for manufacturing structural laminated timber elements made of locally-grown maritime pine is addressed, also by referring to the results of a research activity devoted to this purpose.
... In LCC, only the processes that impose economic costs, mainly direct costs, are considered for the analysis. In addition, external environmental costs, such as carbon emissions, will also be included (Lu et al., 2017). The functional unit is the 1.00 kg of nZVI produced. ...
Article
Nano-scale zero-valent iron (nZVI) is the main nanomaterial used in environmental remediation processes. Its wide application is due to its various characteristics, such as high specific surface area, low toxicity, and low production costs. However, as with any remediation technique, the use of nanomaterials can also cause undesirable impacts on human health and the environment. Thus, this study aims to characterize and analyze the environmental and economic impacts of the production methods of nZVI used in the remediation of contaminated sites. For this purpose, an evaluation of the lifecycle of these environmental (LCA) and economic (LCC) aspects was performed for three methods of nZVI synthesis: milling, liquid chemical reduction with sodium borohydride, and chemical reduction with hydrogen gas. For the analysis of environmental impacts, a lifecycle assessment tool called Simapro was used. This LCA was performed using the ecoinvent database and the Impact 2002 + method, that is, using four impact categories (climate change, ecosystem quality, resources consumed, and human health). For the economic aspects, an analysis of the lifecycle costs (LCC) was carried out, and a specific method was adopted in Simapro, evaluating the internal and external costs. The limits of the system included the stages of raw material extraction and manufacturing, not considering the use of nZVI after its production. The functional unit considered was the kg of nZVI produced. The results indicated that the method involving reduction with sodium borohydride will create the less significant environmental impacts, while the hydrogen gas reduction method results in greater environmental impacts. The LCC demonstrated that the milling method results in lower costs compared to the hydrogen gas reduction method. Thus, it can be said that the methods with the greatest environmental and economic benefits are the reduction with sodium borohydride method and the milling method. These methods are simple and with lower impacts and costs compared to the hydrogen gas reduction method. In this way, the application of the LCA and LCC assists in the evaluation of the environmental and economic performance of the production methods, promoting a broad analysis of the main elements that contribute to the environmental and health impacts of each method.
... In the production phase of buildings, the selection of materials has a key role in CO 2-eq emission. Studies from several countries have shown that wood materials used in building frames usually release less CO 2 than other materials throughout the life cycle [25][26][27][28][29][30]. This is due to the relatively small amount of energy needed to manufacture wood products compared to other materials and the opportunity of replacing fossil fuels with wood byproducts during the manufacturing process. ...
Article
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The building sector is one of the major contributors to global CO2 emission. The energy retrofit of existing buildings reduces CO2 emission in the operation phase but entails new emissions to produce, maintain and dispose the materials used for retrofitting (non-operation CO2 emission). This study analyses the life cycle carbon balance of a building retrofitted to passive house level, considering two alternative standards applicable in Sweden. The study considers the implications of using different building materials for thermal insulation, building façade and windows of the retrofitted building. It also considers different electricity production scenarios, assuming standalone production with fossil coal, fossil gas, and a mix of wind and biomass. Our results show that the operation CO2 emission decreases by between 50-82% in the retrofitted building depending on the passive house standard, with minor deviations between electricity scenarios. The non-operation CO2 emission accounts for between 4-25% of the operation CO2 savings depending on the passive house standard and material option. Deviations between material options are increasingly reduced when assuming fossil gas and wind/biomass for electricity production instead of fossil coal. A careful selection of materials can reduce the net CO2 savings by up to 68%, especially when using wood material.
... Chou and Yeh (2015) argued that the construction industry is regarded as one of the main contributors to global CO 2 emissions. Australia's construction industry emissions accounts for a quarter of Australia's greenhouse gas (Lu et al., 2017). Buildings in Canada contribute 35% of greenhouse gas emissions (Ruparathna and Hewage, 2015). ...
Article
We establish a metafrontier total factor carbon emission performance index (NMTCPI) of 30 provinces’ construction industry in China during 2004–2017. In order to avoid the problem of two efficiency decomposition terms which includes the best practice gap ratio and technical gap ratio greater than 1, the non-radial directional distance function is modified. The results are concluded as follows: (1) Carbon emissions efficiency in China’s construction industry is at low level and grows rapidly during 2004–2017, the potential for CO2 emission reduction is huge. (2) Decomposition analysis reveals that the increase of NMTCPI principally attributed to technical progress. Technical efficiency has gone through a process of first decline and then rise, which means that the construction industry has changed from extensive development to a low-carbon development model. However, the regional technology gap continues to widen after 2011. (3) Different regions have different driving forces. The improvement of carbon emission efficiency in the eastern region comes from the narrowing technical gap and technical progress, while the increase of carbon emission efficiency in the central and western regions is due to rapid technical progress. For most provinces in western group, the sharp decline in technical efficiency hinders the growth of carbon emission efficiency.
... However, the choice of building envelope materials may also influence the maintenance needs and end-of-life related impacts. Moreover, several studies [23][24][25] report climate and environmental benefits for timber frame buildings mainly due to significant wood material recovery over the production and end-of-life phases for energy purposes. Further studies should consider these aspects in a life cycle perspective. ...
Article
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In this study, we analyse and compare the primary energy use and carbon dioxide (CO 2 ) emissions associated with different insulation, cladding and frame materials for a constructed concrete frame multi-storey residential building in Sweden. Our approach consists of identifying individual materials giving the lowest primary energy use and CO 2 emissions for each building envelope part and based on that, modelling different material combinations to achieve improved alternatives of the concrete frame building with the same operation energy use based on the Swedish building code or passive house criteria. We analyse the complete materials and energy chains, including material losses as well as conversion and fuel cycle losses. The analysis covers the primary energy use to extract, process, transport, and assemble the materials and the resulting CO 2 emissions to the atmosphere. The results show wide variations in primary energy and CO 2 emissions depending on the choice of building envelope materials. The materials for external walls contribute most to the primary energy and CO 2 emissions, followed by foundation, roof and external cladding materials. The improved building alternatives with wood construction frames, wood external cladding, expanded polystyrene as foundation insulation and cellulose insulation in the external walls and roof result in about 36 - 40% lower production primary energy use and 42 – 49% lower CO 2 emissions than the improved concrete alternative when achieving the same thermal performance. This study suggests that strategies for low-energy buildings should be combined with resource-efficient and low carbon materials in the production phase to mitigate climate change and achieve a sustainable built environment.
... Ogunbiyi et al., 2014;Koch and Bertelsen, 2014;Sertyesilisik, 2014;Koskenvesa and Sahlstedt, 2012;Salvatierra-Garrido and Pasquire, 2011;Vieira and Cachadinha, 2011;Bashir et al., 2011) (Weinheimer et al., 2017,(Nesteby et al., 2016),(Berroir et al., 2015;Nowotarski et al., 2016;Getuli et al., 2017),(Verrier et al., 2015;Dakhli et al., 2017;Maltese et al., 2017;Dallasega and Rauch, 2017;Alwan et al., 2017;Weinheimer, 2016;Johnsen and Drevland, 2016; Aarseth et al.Ahuja, 2013a;Marhani et al., 2013;Marhani et al., 2012; Ahuja, 2013b)(Li et al., 2017),(Jamil and Fathi, 2016),Dixit et al., 2017;Sapuay, 2016;Wang et al., 2015;Mohamad Bohari et al., 2015),(Belayutham et al., 2017;Ansah and Sorooshian, 2017;Ahuja et al., 2017;Mkrtchyan and Lokhova, 2017;Fadeyi, 2017;Zhu et al., 2018;Kim et al., 2015; Cao et al.Golzarpoor et al., 2017;Wu and Wang, 2016;Chong et al., 2017;Lu et al., 2017; Caldera et al.Aziz and Hafez, 2013),(Issa, 2013) ( Cherrafi et al., 2016,(Bajjou et al., 2017a),(Ganiyu et al., 2015; Khodeir and Othman, 2016;Besser Freitag et al., 2017;Research methods used by authors of the review papers. ...
Article
Academicians and professionals in the architecture, engineering, and construction (AEC) field have expressed an increasing interest in sustainability and its application in the development of construction projects, especially with its deemed relationship with lean construction, for the purpose of improving efficiency in the construction processes. Practices framed under the lean philosophy show their potential in reducing environmental, economic, and social impacts during the construction phase, with an increase in the parameters of sustainability in the development of projects. This article is a review of the extant literature, in an effort to establish the relationships and synergies between the philosophies of lean and sustainable constructions, and to determine how the lean construction practices contribute to each dimension of sustainability (i.e., environmental, economic, social) during the construction phase of a project. A matrix is presented to show the positive effects generated by lean practices on the three dimensions. Moreover, this study identifies the lean construction practices more commonly mentioned in the literature and those that bring further economic, social, and environmental benefits. The analyses and findings of this literature review offer a starting point for future research that integrate lean and sustainable construction during the construction phase.
... While the most common impact category addressed was Global Warming Potential (calculated in 14 papers), 8 categories were selected just once, and 11 categories, twice. Lu et al., 2017;Minne & Crittenden, 2015;Silvestre et al., 2015), 10000 (Blengini & Di Carlo, 2010;Hasik et al., 2017;Huijbregts, 2003), 20000 (Aktas & Bilec, 2012) Hoxha et al. (2014) developed an analytic method for uncertainties of building materials based on the Taylor's series expansion, including sensitivity and contribution analyses, and relying on the pedigree matrix when available data was limited. Hoxha et al. (2017) improved the method, by including variance analysis. ...
Conference Paper
Life Cycle Assessment (LCA) is a systematic and analytical process used to assess environmental impacts related to every life cycle's stage of any given material or process. Over the years, LCA has proven to be a valuable tool in the construction industry in supporting decision-making for mitigating emissions, saving water and reducing the environmental burden of construction materials, infrastructure and buildings. In making LCAs feasible, uncertainties and variability become inherently part of the process, but are seldom explicitly and adequately taken into account. When it comes to whole buildings, it is common to find LCA studies without any sort of uncertainty analysis or treatment. When uncertainty analysis is included, methods for doing so vary, compromising comparability and reliability. Developing a method to address uncertainties in whole building LCAs is a major step to consolidate the technique as the standard guidance for environmental impact-driven decision-making in building design and delivery. Hence, a systematic literature review was conducted to confirm if there is an efficient procedure available in the literature to estimate, treat and minimize parameter uncertainties. Our review clearly pointed out a lack of standardization in the whole building LCAs conducted, and in uncertainty analyses carried out within them. We also found a frequent combination of unrepresentative data and poorly conducted uncertainty analyses. No single uncertainty analysis method seems to efficiently generate accurate results, but using the Monte Carlo simulation to assess uncertainties in LCAs at whole building level constitutes a solid trend. Moreover, recent literature suggests that this approach can be further improved, by combining quali-quantitative multi-methods.
... In addition, the construction sector uses 50% of the global resources (Achal et al. 2015). More than 40% of carbon emissions and 35% of wastage are produced by the building industry (Lu et al. 2017). An holistic evaluation of different building systems is required to inform decision making. ...
Article
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PurposeAspects of the lifecycle sustainability of modular and prefabricated construction remain unexplored. In particular, the characteristics of various concrete techniques require further investigation. This study assessed three different construction techniques, namely, On-site concrete (OSC), Individual Panel System (IPS), and Prefabricated Prefinished Volumetric Construction (PPVC).Methods The following environmental impact criteria were studied: greenhouse gas (GHG), ozone layer depletion (OLD), human toxicity (HT), fossil depletion (FD), and terrestrial ecotoxicity (TE). These were calculated using life cycle assessment (LCA) analysis. The total cost of each case studies was calculated using LCC and a social survey was also conducted using a questionnaire survey. The significance weights were incorporated into an analytic hierarchy process (AHP) for use in multi-criteria decision making (MCDM: TOPSIS).ResultsPPVC was assessed as the best construction technique for most of the environmental criteria. It was 6%, 2%, and 6% lower than OSC in GHG, FD, and OLD, respectively. On the other hand, OSC was shown to be an economic method by 2.4% and 4% having lower cost than PPVC and IPS. Additionally, PPVC achieved the best value in Social-LCA.Conclusions Finally, since different concrete construction techniques were nominated as the best for each criterion, an assessment of multi-criteria was conducted. The results of MCDM showed that PPVC is the most sustainable method among the alternatives. Furthermore, two sensitivity analyses were performed to dispense with the human subjectivity involved in AHP.
... Likewise, Brennan et al. (2014) identified many challenges with inefficient strategies of CDWM, such as ineffective management of waste during the construction and demolition phase. Other studies have also considered the significance of CDWM during procurement and planning and design phases (e.g., Dejkovski, 2016;Lu et al., 2017;Udawatta et al., 2015b). One possible explanation for this inconsistency can be attributed to imbalance perception of CDWM stakeholders towards different life cycles of a project in CDWM. ...
Article
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The construction industry accounts for an enormous quantity of construction and demolition waste (CDW) where its improper management jeopardizes social, environmental, and economic resources. Although several studies have investigated some aspects of construction and demolition waste management (CDWM), there is a substantial need to empirically analysing effective construction and demolition waste management (ECDWM) considering its contributing factors and the CDWM hierarchy (CDWMH). A framework was proposed to assess the effectiveness of CDWM using CDW stakeholders’ attitudes (CDWSA), CDWM within project life cycles (CDWPLC), CDWM with respect to sustainability (SCDWM), and CDWM tools (CDWMT) as factors that effectively affect CDWM, and CDWMH as the most effective strategy to manage CDW, leading to the effective management of CDW. This study analyzed ECDWM in Australia. Thus, 108 large construction companies were approached via an online questionnaire. Data were analyzed through partial least squares based structural equation modelling using SmartPLS. Results (path coefficients) could prove that CDWSA was the most effective factor to CDWM, while CDWPLC was the least effective (ineffective). In addition, recycling strategy received more attention than reusing and reducing strategies, which contrasts with the nature of CDWMH. The study is relevant for CDW professionals as well as academicians involved in CDWM.
... This is the reason why it is so suitable as construction material. Wood-based materials can achieve both efficient environmental and economic benefits [4]. When comparing engineering wood (cross-laminated timber) with concrete and steel structures, the first show a lower environmental impact [5,6]. ...
Article
Full-text available
Multiple high quality wood waste from a window manufacturer is identified and collected. Eco-sustainable panels, with promising acoustic and thermal insulating performance, were then fabricated. The available wood is of different tree species (pine, oak, and mahogany) and size (pieces of wood, mixed coarse chips, and mixed fine chips). Moreover, scraps of olive tree pruning from local areas were collected for reuse. The aim of the research is to assembly panels (300 × 300 mm2) both with different techniques (hand-made and hot-pressed) and type of adhesive (vinyl and flour glues) and to evaluate their thermal, acoustic, and environmental performance. All the panels present thermal and acoustic performance comparable with the similar ones available in the literature or with commercial solutions. The thermal conductivity varies in the 0.071 to 0.084 W/mK range at an average temperature of 10 °C, depending on the tree species, the assembly technique, and regardless of the type of adhesive used. Oak wood panels are characterized by both better sound absorption (α peak value of 0.9, similar to pine pressed sample with flour glue) and insulation (transmission loss up to 11 dB at 1700 Hz) properties. However, their added value is the low environmental impact assessed through life cycle analysis in compliance with ISO 14040, especially for panels assembled with natural glue.
... Life cycle assessment has been widely applied to evaluate the environmental impacts of buildings [20] and the building sector [21]. Some literature has conducted the life cycle assessment from the perspective of building component or material; for instance, Lu et al. [22] conducted a life cycle study to assess various materials for constructing an apartment's structural frame in Australia. Some has assessed the LCE at the single building scale [23], such as LCE studies on a typical large office building in Tianjin [24] and a passive housing block in Austria [25]. ...
Article
The residential building sector is a substantial contributor to energy use in Australia. In existing studies, life cycle energy (LCE) of residential buildings is seldom evaluated from the multi-scale perspective and such considerations rarely consider building typologies. This study presents a bottom-up framework to evaluate the LCE of residential buildings at multiple scales, including the component, building and regional levels. This framework can synthetically connect LCE between different scales and assess inter-scale impact in the built environment. In this framework, residential buildings are classified by embodied impact attributes (housing type, construction year, and construction type) and operational impact attributes (occupancy schedule, fuel type, and climate zone). In this paper, the framework is further applied to evaluate the LCE of residential buildings in the context of Victoria, Australia. The research results provide valuable references about energy intensities of various residential building typologies. The research findings suggest that operational energy (OE) of new housing has reduced significantly because of the improvement of technologies and the energy-saving requirement by the government. As a result, the proportion of embodied energy (EE) in dwelling's life cycle has increased from 9%–35% (old dwellings) to 66%–71% for dwellings built after 2011. At the regional scale, the LCE is composed of 79% OE and 21% EE in Victoria. The largest part of OE is contributed by the energy use for heating (39%), and appliances are the second most energy consumers (32%). Meanwhile, the energy embodied in concrete accounts for the largest part (908 PJ) of total EE. The comprehensive profile and interplay of LCE across different scales can help decision-makers to identify the key contributor to LCE and take targeted measures to improve the energy performance of the built environment.
... Wood is a natural and renewable material. Hence, increasing its use within the construction industry could help in the ongoing campaign to reduce the greenhouse gases produced by the construction sector (Thornley et al., 2015;Riffat et al., 2016;Lu et al., 2017;Hart and Pomponi, 2020). In relation to this, several actions are being set up to encourage and promote the use of wood in the construction industry. ...
Article
Full-text available
In recent years, there has been an increasing interest of engineers and architects in the use of timber in the construction sector. This worldwide trend can be mainly attributed to the reduced environmental impact of building with timber, its high strength-to-weight ratio and its renewable material nature. Nevertheless, in spite of the advantages of building with timber, one of its major disadvantages is its time-dependent structural response. For instance, typical floors and beams made of timber may show decreasing stress levels under constant deformation over time. This phenomenon is known as stress relaxation and can also be affected heavily by environmental factors, such as temperature and moisture changes. This has inevitably led to discourage the use of timber in the construction industry. Due to the relevance of this subject, the present paper addresses the stress relaxation phenomenon in timber specimens subjected to three-point bending loads. In particular, radiata pine species is chosen for this investigation given its popularity as a building material in countries like Australia, Chile, Spain and New Zealand, among others. To investigate experimentally the influence of temperature and relative humidity on the stress relaxation at different deformation states, an environmental chamber was built. The stress relaxation is assessed indirectly by monitoring the relaxation of the load required to maintain the amount of deformation fixed in time inside the environmental test chamber. The experimental results show that within a period of 7 days, the percentage of load relaxation may reach a value of 35% approximately, for a fixed relative humidity of 60% and constant temperature of 27∘C\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${27}\,^{\circ }\hbox {C}$$\end{document}. The present experimental results provide further insight into the time-dependent mechanisms of timber which are still not well-understood, and particularly of those structures made of radiata pine grown in Chile on which only limited experimental data has been reported to date.
... However, problems can include: (1) it is not clear how these critical variables are identified; and (2) result shows the variables may not be critical, impeding a better understanding of the uncertainty. A case is, in Lu et al.'s study [107], three variables (change between − 10% and +10) were presumably selected to check their uncertainties, and emissions from transportation processes was tested to be insensitive. In comparison, a hotspot analysis was undertaken by Wang et al. [108] to search the significant variables (i.e., transportation) and then calculated its variability. ...
Article
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Environmental impacts (EIs) of building stocks have been receiving significant attention in recent decades as they consume more than 40% of the world's energy, release one third of total greenhouse gas emissions, and account for 30% of global landfill waste. Prior efforts have focused on mitigating EIs during the operation stage of buildings, while the environmental performance of other stages is relatively overlooked. Addressing this, whole-building life cycle assessment (WBLCA) has gained prominence from a life-cycle perspective to ensure the best environmental performance. However, there is an array of factors that can affect WBLCA results, and such uncertainties render decisions made for sustainable development untenable. Aiming to understand the comprehensive uncertain sources of WBLCA (what) and their corresponding solutions (how), this paper systematically reviews existing publications on WBLCA, presents its status and challenges, and analyses the taxonomy of uncertainties and eight uncertainty methods and variants thereof. Accordingly, a framework is developed that enables LCA practitioners to readily understand the correlation between WBLCA uncertainties and solutions, and conveniently locate and appraise them throughout the WBLCA process. Upon answering the known-what and known-how questions, this study contributes to the body of knowledge of LCA by providing a comprehensive and systematic methodology to evaluate the EIs of buildings.
... At the project level, the research on construction carbon emission reduction management mainly focuses on the measurement calculation method of construction carbon emission and collaborative emission reduction management. Carbon emission measurement and collaborative management of carbon emission reduction are carried out for different life cycle stages of buildings [27], building materials [28], building components and parts [29,30], building structure forms [31], etc., to provide reference for low-carbon building design and whole life cycle management. At the regional level, the research on construction carbon emission has mainly focused on the calculation of construction carbon emission and the study of influencing factors. ...
Preprint
To explore the spatial network structure characteristics and driving effects of carbon emission intensity in China's construction industry, the investigation combined the modified gravity model and social network analysis method to deeply analyze the spatially associated network structure characteristics and driving effects of carbon emission intensity in China's construction industry, based on the measurement of carbon emission data of China's construction industry from 2006 to 2017. The results show that the regional differences of carbon emission of construction industry are significant, and the carbon emission intensity of construction industry show a fluctuation trend. The overall network of carbon emission intensity shows an obvious “core-edge” state, the hierarchical network structure is gradually broken. Economically developed provinces generally play a leading role in the network, and play an intermediary role to guide other provinces to develop together with them. Among the network blocks, most of the blocks play the role of “brokers”. The block with the leading economic development has a strong influence on the other blocks. The increase of network density, the decrease of network hierarchy and network efficiency will reduce the construction carbon emission intensity.
... Their results revealed that wooden houses have greater performance than concrete and steel houses in terms of embodied energy and GWP. They also showed that steel and concrete had the largest environmental burden in all impact categories in construction phase (Lu et al. 2017). In a study, a life cycle energy assessment was applied on a multi-storey residential building and they showed that steel (39.2%), cement (17.9%), aluminum (13.8%) and concrete (9.2%) are the major contributors of the life cycle energy in construction phase (Mehta et al. 2017). ...
Preprint
Full-text available
In recent years, there has been a significant transition from multi-storey buildings to single-family houses especially due to COVID-19 pandemic. Thus, people prefer to live in single-family houses or detached houses where they have more free space in outside of the house. The aim of this study is to quantify and compare the environmental performance of a single-family house and multi-storey apartment building in Turkey throughout their life cycle with cradle-to-grave approach. Life Cycle Assessment (LCA) based on ISO 14040 and ISO 14044 was used to analyse the environmental impacts of the single-family house and multi-storey apartment buildings. The functional unit was chosen as 1m ² of floor area of a house over their lifespan (50 years). With cradle-to-grave approach of the LCA, the system boundaries for the environmental assessment covers the pre-operation, operation and post-operation stages. The results of this LCA study revealed that majority of the environmental impacts occurs at operation phase for both single-family house and multi-storey apartment. The operation stage has the highest impact with 79% and 78% share of the global warming potential (GWP) for single-family house and the multi-storey apartment, respectively. In comparison of environmental impact results, GWP of the multi-storey apartment per m ² of floor area is 30% lower than single-family house. The environmental impacts of the operation phase have significant importance on the overall environmental performance of both single-family house and multi-storey apartment. The results showed that electricity consumption and steel usage are the main contributors of the environmental impacts coming from the operation and pre-operation phases, respectively. To pave the way to a sustainable future, the building industry must strive to use of renewable energy sources and sustainable construction materials in order to reduce their environmental impacts with a sustainable approach.
... We are increasingly confronted with the decision making of future users regarding wood constructions [62] on the basis of their preferences with respect to the material and technological base [63]. Another important factor in this decision-making process is certainly the economic criteria influencing the overall efficiency of a particular technology within the construction life cycle [64,65]. All of this is also associated with the basic sustainability criteria that are commonly used today [66,67]. ...
Article
Full-text available
Traditional construction solutions face increasing competition from more ecological materials such as construction systems based on wood. Thanks to the numerous favourable properties of wood, wood construction enjoys great popularity and allows building economical and modern constructions that are durable and contribute to an ecological future. This study is motivated by the need for innovative solutions in construction and offers numerous findings based on examining actual constructions based on wood. By examining the interactions among selected factors of constructions and their users, the study reacts to the global challenges that call for increased efficiency and sustainability in construction. The examination of the interactions among the selected factors offers more extensive knowledge in the field of constructions based on wood and points towards possible innovative approaches for more sustainable housing and for a more efficient construction industry. The analyses showed that the key aspects that determine the sustainability of housing from the perspective of users are the standard of construction workmanship and construction time, which depend on the choice of construction system, cost-efficiency of use, and material composition and floor plan design. These aspects also interacted with other technical and design aspects, which also played an important role in the perception of housing sustainability.
... These sections have the potential to be used in structural applications [1,3] and are seen, for instance, as a potential solution for utility poles [1] and the main frame of buildings. They have the advantage of having an efficient cross-sectional shape, are sustainable [4][5][6], and able to be manufactured in usable lengths [2] and cross-sectional sizes that are no longer available in sawn timber. ...
... Meanwhile, the construction sector uses 50% of the global resources worldwide [1]. The building industry produces more than forty percent of carbon emissions and thirty-five percent of wastage to the environment yearly [38]. Thereby, evaluation of the building system still seems vital to decreasing any opportunity from this sector. ...
Chapter
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Lately, many governments have been significantly promoting modular building instead of conventional as a practical solution toward enhancing sustainability in the construction sector. Therefore, this research aims to compare traditional and modular building construction to find each environmental and cost difference as a criterion for comparison. This study's life cycle sustainability assessment comprises embodied energy, greenhouse gas (GHG), and cost. The result showed that the steel modular has the lowest embodied energy and carbon emission following conventional steel construction. For traditional construction, 28% of GHG emissions are related to on-site activity, while PPVC is less than 1%. However, the development of the factory is about 11% of the total construction emission for PPVC. On the other hand, the concrete, conventional method has a lower construction cost following by concrete modular. The transportation cost of modular building is responsible for up to 13% of the total construction cost. While the conventional building has a higher worker wage by 11%, compare to modular construction. Multi-attributes decision-making (MADM) using WASPAS has been applied to reveal the best construction material and method. The result showed that steel modular is the best option for construction.
Article
A comparative lifecycle assessment (CLCA) was undertaken to determine the environmental effect or impact of teleworking compared to office-based work in a corporate setting in Australia. Teleworking was demonstrated to have smaller environmental effects than office-based working, but only under certain conditions. Teleworking was more beneficial if an employee travels ≥30 km each workday. The more energy efficient the employer’s buildings are, the lower the environmental value of teleworking. Greater energy efficiency in home offices means greater environmental benefits. If the energy used in the remote (residential) work area increases above 1212 kW h of energy per year, the environmental effects become greater than those from non-teleworking. The greater the use of renewable energy in remote compared with commercial offices, the greater the environmental benefits of teleworking. Rational corporate policy recommendations were developed based on these outcomes.
Article
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Products derived from trees have been used by mankind for thousands of years, where timber has a long tradition as an ecological construction material. There is currently an increasing trend in multi-storey timber buildings, because of the projected growth in the demand for housing in urban areas between now and 2050, along with the urgent need for a more sustainable and productive construction industry. The construction of these buildings is now possible thanks to the new advances in architecture, engineering, and construction (AEC) and the new technological developments around timber construction. Its industrialization requirements imply a paradigm shift for the construction industry, which requires, among other aspects, the early and collaborative integration of stakeholders in its design and construction process. According to this, the objective of this review article is to determine the main advances and limitations related to the design and construction of multi-storey timber buildings, categorizing them in aspects such as sustainability, engineering and construction sciences, and collaborative design. The methodology of this article was based on the review of 266 articles published in Web of Science (WoS), as indexed scientific journals, between 2017 and mid-2022, performing a comparative and cooccurrence analysis of the contents. The results evidenced that 73% of the articles showed advances and limitations corresponding to the engineering and construction sciences category, 23% to sustainability, and the remaining 4% to collaborative design. The main advances in the development of multi-storey timber buildings are related to seismic analysis, connections design, fire performance, and fire design. While the main limitations are related to social sustainability, the results are not conclusive due to the low number of publications that support them.
Article
Life cycle assessment (LCA) has been widely used to determine the environmental impact of mass timber construction (MTC) as a substitute for conventional construction. This article presents a systematic review of MTC from a life cycle assessment perspective. The goal and scope definition, life cycle inventory analysis, impact assessment and interpretation are examined and analyzed in 62 peer-reviewed articles. The results show the variety in scope, lifespan, system boundary, data sources and indicators. Studies on MTC have been conducted at the building material, component, structure, and entire building levels, as well as at the urban level. The majority of studies compare the LCA of reinforced concrete (RC) and cross laminated timber (CLT) buildings. The global warming potential (GWP) and life cycle energy are the most frequently evaluated category indicators among the articles. It is found that the average embodied energy of mass timber buildings is 23.00% higher than that of RC alternatives, while the average embodied greenhouse gas (GHG) emissions of RC buildings are 42.68% higher than that of mass timber alternatives. There is a clear general trend that mass timber buildings generally have lower GWP and life cycle primary energy (LCPE) than RC and steel buildings. Eventually, sensitivity analysis, carbon storage and outlook of the mass timber are also reviewed and discussed in the literature.
Article
Research concedes that the building industry in Australia has fallen short of satisfying sustainability requirements. Currently, the responsibility for transitioning the building industry into one that is sustainable is laid largely at the feet of low-carbon governance instruments such as mandatory codes and sustainability rating tools. The behavior of groups, interactions of individual actors, relationship between actors’ and group level behaviors that affect implementation of these instruments have, however, received only cursory attention. This study therefore seeks to move beyond the instruments debate and identify a broader range of factors inhibiting the transition to sustainability within the Australian building industry. It draws on focus group discussions held with 26 leading sustainability experts and practitioners from around the country. Whereas, earlier work on impediments to sustainability pre-identify potential causal factors, this study, with Sustainability Transition as the theoretical lens, allowing for new and as yet unidentified impediments to emerge. Indeed, while findings confirm a range of technical shortcomings hindering sustainability transition, the deeper barrier is shown to be the prevalence of a dysfunctional sustainability ecosystem where siloed vested interest groups exploit Australia’s ineffective transition regimes for their own gain. The practical implication is that current efforts to refine rating tools and modify building practices – remedies identified in earlier research – will not be enough to effect meaningful transition, as long as end-users remain disenfranchised, confused and unpersuaded of the benefits of sustainable buildings.
Article
Primary energy implications over the life cycle of a multi storey residential building with different building systems are explored here. The main structural materials of the buildings include precast concrete, cross laminated timber (CLT) and prefabricated timber modules (modular). The analysis covers energy and material flows from different life cycle phases of the building versions, designed to meet the energy performance of the Swedish building code (BBR) and passive house criteria. The CLT and modular buildings were found to result in lower production primary energy use and higher biomass residues compared to the concrete alternative. The heating value of the recoverable biomass residues from the production phase of the CLT building is significantly larger than the primary energy required for its production. Primary energy use for production and construction constitutes 20–30% and 36–47% of the total primary energy use for production, construction, space heating, ventilation and demolition for the BBR and passive buildings, respectively. Space heating with combined heat and power (CHP) and ventilation electricity for the BBR and passive building versions form 70–79% and 52–63%, respectively, of the total primary energy use for production, construction, space heating, ventilation and demolition for a lifespan of 80 years. The CLT and modular buildings give 20–37% and 9–17% lower total life cycle primary energy use, respectively, than the concrete alternative when space heating is from CHP.
Article
In recent years, wood has received increased interest in Europe as a multi-storey building material. The trend is driven by the recognition that wood, as an environment friendly material, can contribute bioeconomy development and the achievement of sustainable development goals. In Lithuania, multi-storey wood-based building is still at the level of policy and political discussions. Therefore, the presented research focuses on quantification and comparison of the sustainability impacts of both wood- and concrete-based building materials value chains and provides applied scientific knowledge relevant to decision makers and in this way contributes to mitigation of the climate change. In detail, study covers the production value chain – from raw material extraction to manufacturing using the same method, while documenting and assessing the material sourcing stages transparently and consistently. In our study glue laminated timber and sawn timber building materials represented renewable material value chains, while site-cast concrete and precast reinforced concrete building materials represented non-renewable materials value chains. In discussion with study partners in the BenchValue project and during a project stakeholder workshop, twelve environmental, social and economic indicators were selected to perform the sustainability impact assessment of selected building materials. Building materials were compared by using a decision support tool ToSIA. The relevant data was gathered from local, well-known companies in the national and international arena. Our results revealed that glue laminated timber and sawn timber value chains compared to site-cast concrete and precast reinforced concrete value chains have more positive sustainability impacts. This is especially true when analysing environmental indicators: GHG emissions, Energy use, Generation of wastes and Water use. Analyses also revealed more positive socio-economic impacts of wood-based building materials. The socio-economic advantage of wood could increase competitiveness of the regions and contributes to their sustainable development. Our paper is in line with the applied research. Since it is a case study, the presented results are country specific, because the estimation of indicators was done by applying local data. The presented research is relevant to policy experts and decision makers in the context of the reduction of CO2 emissions. Also, this paper is relevant to the companies and architects who want to build and compare various building materials. Partially, results of this paper could be applied in other countries with comparable to Lithuania economic development level, having in mind the possible shortcomings already highlighted.
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The development of materials in the construction industry has a direct impact on greenhouse gas emissions - GHG, throughout the entire construction process from production, use and reuse. Being able to evaluate the energy embedded in the entire process is essential to establish criteria that allow the corresponding emissions to be calculated. The environmental impact of the building can be reversed through the appropriate use of materials referenced in the vernacular architecture if aspects of the life cycle characterized by standardized and regulated data on CO2 (Carbon dioxide) emissions are considered. This research has analyzed existing information on CO2 emissions of natural or traditional materials based on standardized data contained in 266 EPD (Environmental Product Declaration). It is important to generate this type of information so that it can be implemented in official construction databases. Specifically, 815 materials have been analyzed, based on their environmental impact, and a comparison of data – emission values, according to vernacular and non-vernacular materials – has also been developed, identifying on the importance of the use of traditional materials in vernacular architecture.
Article
Purpose-Whole building life cycle assessment (WBLCA) is a key methodology to reduce the environmental impacts in the building sector. Research studies usually face challenges in presenting comprehensive LCA results due to the complexity of assessments at the building level. There is a dearth of methods for the systematic evaluation and optimization of the WBLCA performance at the design stage. The study aims to develop a design optimization framework based on the proposed WBLCA method to evaluate and improve the environmental performance at the building level. Design/methodology/approach-The WBLCA development method is proposed with detailed processes based on the EN 15978 standard. The environmental product declaration (EPD) methods were adopted to ensure the WBLCA is comprehensive and reliable. Building information modeling (BIM) was used to ensure the building materials and assembly contributions are accurate and provide dynamic material updates for the design optimization framework. Furthermore, the interactive BIM-LCA calculation processes were demonstrated for measuring the environmental impacts of design upgrades. The TOPSIS-based LCA results normalization was selected to conduct the comparisons of various building design upgrades. Findings-The case study conducted for a residential building showed that the material embodied impacts and the operational energy use impacts are the two critical factors that contribute 60-90% of the total environmental impacts and resource uses. Concrete and wood are the main material types accounting for an average of 65% of the material embodied impacts. The air and water heating for the house are the main energy factors, as these account for over 80% of the operational energy use. Based on the original WBLCA results, two scenarios were established to improve building performance through the design optimization framework. Originality/value-The LCA results show that the two upgraded building designs create an average of 5% reduction compared with the original building design and improving the thermal performance of the house with more insulation materials does not always reduce the WBLCA results. The proposed WBLCA method can be used to compare the building-level environmental performances with the similar building types. The proposed framework can be used to support building designers to effectively improve the WBLCA performance.
Article
The buildings and construction sector account for a significant part of the total energy use and related greenhouse gas emissions. However, climate change mitigation often becomes secondary or completely disregarded in building design assessment as the primary concern of building owners are economic tenability. Therefore, this study introduces an Extended Life Cycle Cost Assessment that include monetary evaluation of climate risk and opportunities in terms of Social Cost of Carbon (SCC). SCC could function as a tax to promote climate change mitigation within e.g. the construction industry. The purpose is to provide a more holistic assessment approach that is easy to relate to if economic tenability is of primary concern in decision making, which can be used to assess building design. Return on invested greenhouse gas emissions is used as an additional or standalone indicator for climate change mitigation. The introduced approach is exemplified by a case study where renovation and new construction are compared with keeping buildings in its original design. The case study show that with or without a flat greenhouse gas tax, renovation is the most climate and cost efficient alternative.
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Wood is one of the basic natural renewable materials. Knowledge of its basic properties is the first prerequisite for its proper use in various industries and in human life. Wood is the most versatile and most used material (industry, construction, agriculture, everyday life). Due to its natural character, natural drawing, favorable physical properties, it is an increasingly desirable element of the environment. In the world, but also in our country, the trend of wooden buildings is becoming more and more widespread, not only in the understanding of cottages, wooden houses and family houses using wooden elements. We are talking about office buildings, non-residential premises, but also wooden high-rise buildings. Multi-storey wooden structures are a promising area of application of wood, which requires much less energy for their production compared to other "classic" materials. The aim of this paper is to present selected aspects of multi-storey wood-based buildings and their application at present.
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This paper discusses the ancient house building architecture which has been reflected in the text of Bṛhatsaṁhitā. Bṛhatsaṁhitā is verily associated with the Vedas or the knowledge of treasury. Vedas are four in numbers. In the tradition of knowledge, there are also four Upavedas- Dhanurveda, Stāpatyaveda, Gāndharvaveda and Āyurveda. Upavedas are actually known as the applied knowledge of science. These Upavedas are basically designed on technical work. There are so many literatures which have been composed by our ancient seers. Śrīvarāhamihira is the most efficient personality in the ancient science of knowledge. He has written the text of Bṛhatsaṁhitā. This is treated as the technical literature in the language of Sanskrit. There are one hundred and six chapters in this text. The knowledge of all the Upavedas are discussed clearly in this text. The Fifty three chapter of this text is named as Vāstuvidyā or the science of house building. The present study is an attempt to discuss the technique adopted in the science of ancient house building tradition according to Śrivarāhamihira.
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The building and construction sector is a large contributor to anthropogenic greenhouse gas emissions and consumes the vastest amount of natural resources. Widely considered a hard-to-decarbonise sector, improvements in buildings and construction are of fundamental importance for national and global targets to combat climate change. At material level, mitigation opportunities exist in terms of efficiency (using less of the same material) and substitution (using a different material). This article investigates the latter, with a global focus on the use of cross laminated timber to replace concrete floors in steel structural systems. This approach, whilst innovative, does not require any technological development nor upskilling of current professional practice, thus making it an immediately viable solution to accelerate decarbonisation. We combine Material Flow Analysis with Life Cycle Assessment across both spatial and temporal dimensions, accounting for different levels of uptake of the proposed hybrid construction in the next 30 years. Results show that greenhouse gas emissions saving potentials range between 20-80 Mt CO2e (95% confidence interval) with an average around 50 Mt CO2e in the case of full uptake of the hybrid construction system by 2050. Our analysis does not account for carbon sequestration potential in timber, which would make the savings much greater. Still, the overall savings represent a 1.5% reduction of the annual greenhouse gas emissions generally attributed to construction, thus making it a non-trivial contribution to progress towards global targets of net-zero carbon buildings.
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Construction and demolition waste (C&DW) as a direct consequence of rapid urbanization is increasing around the world. C&DW generation has been identified as one of the major issues in the construction industry due to its direct impacts on the environment as well as the efficiency of construction industry. It is estimated that an overall of 35% of C&DW is landfilled globally, therefore, effective C&DW management is crucial in order to minimize detrimental impacts of C&DW for the environment. As the industry cannot continue to practice if the resources on which it depends are depleted, C&DW management needs to be implemented in an effective way. Despite considering many well-developed strategies for C&DW management, the outputs of the implementation of these strategies is far from optimum. The main reason of this inefficiency is due to inadequate understanding of principal factors, which play a vital role in C&DW management. Therefore, the aim of this research is to critically scrutinize the concept of C&DW and its managerial issues in a systematic way to come up with the effective C&DW management. In order to achieve this aim, and based on a systematic review of 97 research papers relevant to effective C&DW management, this research considers two main categories as fundamental factors affecting C&DW management namely, C&DW management hierarchy including reduce, reuse, and recycle strategies, and effective C&DW management contributing factors, including C&DW management from sustainability perspective, C&DW stakeholders’ attitudes, C&DW project life cycle, and C&DW management tools. Subsequently, these factors are discussed in detail and findings are scrutinized in order to clarify current and future practices of C&DW management from both academic and practical perspectives.
Article
Engineering wood products have significant potential as a sustainable alternative for concrete and steel in construction. Cross Laminated Timber (CLT) can add value to conventional timber products due to its high strength-to-weight ratio, simple installation, aesthetic features and environmental benefits. Recent changes in the national construction code permit structural timber buildings with a height of up to 25m, which demonstrates the strong commitment of the construction industry to adopt more sustainable practices. This paper aims to compare life cycle greenhouse gas emissions (LCGHGE) and life cycle cost (LCC) of CLT and reinforced concrete (RC) in identical midrise residential buildings in three most populated cities in Australia. It has shown that the CLT building has 30 % less LCGHGE compared with the RC building over a life span of 50 years in Melbourne, and 34% and 29% reduction in LCGHCE in Sydney and Brisbane, respectively. The results from LCC analysis showed that CLT building is 1.3% lower than conventional RC in Melbourne, and 0.9% lower in Sydney and Brisbane. The initial and end of life phases reflected reductions in LCGHGE and LCC for the CLT building whilst the operation phase incurred higher values. The extended service life of buildings has a major impact on the operational phase while changes in the discount rate have strong effects on the lifecycle operational and maintenance costs. Overall the CLT building outperformed the RC building in terms of LCGHGE and LCC across three cities. However, further savings in the operational phase with energy efficient methodologies and reuse or recycling of timber products at the end of life of the building can reinforce CLT as a sustainable alternative to RC construction.
Article
Different options for treating organic fraction of municipal solid waste were assessed. Four composting scenarios were designed based on different scales (i.e. home vs centralised) and technologies (i.e. windrow vs in-vessel composting) in Brisbane. The environmental and economic performance were analysed and compared to the existing practice: landfilling, using life cycle assessment and life cycle costing analysis with the consideration of the costs of externalities and potential avoided costs. The treatment of 1 Mg of home organic waste was selected as one Functional Unit. The system boundaries start from waste collection to the use of the final product (i.e. compost). The compost was assumed to be applied on private gardens and tropical horticultural crops in home and centralised composting scenarios, respectively. Shared home composting bin in a small community (HC-II) presented the best overall performance from both environmental and economic perspectives, meanwhile, landfilling was found to be the worst option. The home composting scenarios require less energy which results in four times lower fossil depletion and human toxicity potential compared to centralised composting scenarios. However, the greenhouse gas (GHG) emissions released through organic waste degradation, due to potential partial anaerobic conditions, were identified as the major environmental impact factor, followed by the compost bin manufacturing. In both centralised composting scenarios, the energy consumption was found as the main environmental impact factor, which accounted for more than 45% of the total GHG emissions, followed by the waste collection and transportation process. Regarding the economic performance, the HC-II scenario has the lowest life cycle cost ($22.93/FU). Monte Carlo Analysis was carried out to test the effect of overall uncertainties. Our result showed that the compost application rate had the highest sensitivity in home composting scenarios because the unused compost would need to be collected and sent to the landfill. Consequently, extra transportation emissions and life cycle cost will incur, thus, the benefits from compost application will also be reduced. However, the overall uncertainties did not affect the ranking of the centralised (windrow) composting scenario, which remained the best environmental performer. Meanwhile, HC-II option had the better economic performance that marginally over-weighed the environmental performance of the centralised windrow composting; hence result in the best overall performer. However, in order to encourage residents to participate, enabling policies and incentives may be required to influence the behaviour of the independent households to share a composting bin.
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Due to increasing demand for utility poles and the banning of native forests logging in Australia, it is necessary to find sustainable alternatives to roundwood utility poles. Currently, steel and concrete are the most common alternatives. Veneer-based composite (VBC) is a newly developed product made from hardwood plantation mid-thinning. To assess the viability of VBC, comparative life cycle assessment (LCA) and life cycle costing (LCC) analysis were conducted. Two end-of-life scenarios for VBC pole were assessed: incineration with energy recovery and landfilling. Five impact categories were considered: global warming (GWP); acidification (AP); eutrophication (EP); fossil depletion (FDP) and human toxicity (HTP). VBC pole with incineration showed the best environmental performance, particularly on GWP (63.22 kg-CO2-eq), AP (0.29 kg-SO2-eq), FDP (30.78 kg-Oil-eq) and HTP (2.27 kg-1,4-DB-eq), which are less than half of concrete and steel poles. However, VBC had higher EP than concrete and steel du
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Hardwood plantations are slow to mature with low financial returns in the early stage. Veneer Based Composite (VBC) products developed from mid-thinning may improve the industry’s profitability and win new markets. Due to the increasing demand for utility poles and the banning of native forests logging in Australia, VBC poles may become viable alternative to native hardwood poles. Alkaline copper quaternary (ACQ) preservative treated VBC pole was assessed using life cycle assessment (LCA) methodology. The manufacturing processes considered were based on the current technologies in Queensland. VBC pole life cycle stages assessed include mid-thinning, manufacturing, service-life, and disposal. Three end-of-life scenarios were considered: landfilling, incineration for energy recovery and recycling as particleboard. The functional unit used in this assessment is 1-metre-length pole with 115-mm internal-diameter and 15-mm wall-thickness. Global Warming Potential (GWP100), Fossil Depletion Potential (FDP), Acidification Potential (AP), Eutrophication Potential (EP), and Ecological Toxicity Potential (ETP) were quantified. Results indicated that landfilling and incineration outperform the recycling option. Incineration scenario performed slightly better under the GWP100 (0.3659kg-CO -Eq), AP (2.12g-SO -Eq), FDP (0.360kg-Oil-Eq) and EP (3.81g-PO -Eq). Meanwhile, landfilling scenario had slightly less impact in ETP (12.32-CTUe). Despite generating valuable products, the burdens caused by secondary manufacturing and transportation overweighed credits earned from recycling. ACQ treatment, Phenol-formaldehyde (PF) resins production and transportation distances were identified as significant parameters affecting the final result. Sensitivity analysis indicated that EP was sensitive to change in ACQ consumption; ETP was affected by PF resin use while changing distances of transporting product affected GWP100, AP and FDP.
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The objective of this project was to quantify and compare the environmental impacts associated with alternative designs for a typical North American mid-rise office building. Two scenarios were considered; a traditional cast-in-place, reinforced concrete frame and a laminated timber hybrid design, which utilized engineered wood products (cross-laminated timber (CLT) and glulam). The boundary of the quantitative analysis was cradle-to-construction site gate and encompassed the structural support system and the building enclosure. Floor plans, elevations, material quantities, and structural loads associated with a five-storey concrete-framed building design were obtained from issued-for-construction drawings. A functionally equivalent, laminated timber hybrid design was conceived, based on Canadian Building Code requirements. Design values for locally produced CLT panels were established from in-house material testing. Primary data collected from a pilot-scale manufacturing facility was used to develop the life cycle inventory for CLT, whereas secondary sources were referenced for other construction materials. The TRACI characterization methodology was employed to translate inventory flows into impact indicators. The results indicated that the laminated timber building design offered a lower environmental impact in 10 of 11 assessment categories. The cradle-to-gate process energy was found to be nearly identical in both design scenarios (3.5 GJ/m2), whereas the cumulative embodied energy (feedstock plus process) of construction materials was estimated to be 8.2 and 4.6 GJ/m2 for the timber and concrete designs, respectively; which indicated an increased availability of readily accessible potential energy stored within the building materials of the timber alternative.
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Over the last two decades, the olive oil industry in Australia has been growing at an annual rate of 9%. Nevertheless, the highly polluting solid waste and wastewater generated by the industry poses significant challenges for the environmental sustainability of the industry. This paper analysed five alternatives for managing this waste stream using life cycle assessment methodology. The options included manufacturing briquettes as solid fuel for home heating; pellets for domestic or industrial water heating; pyrolysis and composting. The functional unit used in this study is the processing of 1 Mg of olive solid waste at the mill. Emissions were categorised into eight impact categories: ozone layer depletion potential (ODP), global warming potential (GWP100), eutrophication potential (EP), acidification potential (AP), human toxicity (HTP), fossil fuel depletion potential (FDP), ionising radiation potential (IRP), and photochemical oxidant formation potential (POFP). The study showed that although composting (current best practices – CBP) can achieve significant environmental benefits, using the olive waste to produce energy products may achieve better results, especially when displacing electricity from the main grid. The production of pellets for use in domestic hot water boilers (PHWH) is the option that is likely to deliver the highest environmental benefits. For example, GWP100 and ODP of the PHWH were estimated to be −1057 kg CO2-Eq, −1.5 × 10−5 kg CFC-11-Eq compared to −12.4 kg-CO2-Eq and 5.3 × 10−8 kg CFC-11-Eq achieved by the CBP, respectively. Future energy scenario and transportation distances were identified as significant parameters affecting the performance of the options. Sensitivity analysis showed that the expected change in the future Australian energy mix to cleaner energy sources is unlikely to have a significant effect on the performance of the alternatives. The results also showed little sensitivity to transportation distances of the energy product to the end user. This paper is the first to evaluate options for energy utilisation of olive solid waste using life cycle assessment and compare it to industry current best practices (composting). Although the paper focuses on the Australian olive oil industry, the results are also relevant to other countries and regions were olive solid waste is generated in relatively moderate quantities but distributed over large geographic area.
Technical Report
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This study summarizes the environmental performance of prefinished engineered wood flooring using life-cycle inventory (LCI) analysis. Using primary mill data gathered from manufacturers in the eastern United States and applying the methods found in Consortium for Research on Renewable Industrial Materials (CORRIM) Research Guidelines and International Organization of Standardization (ISO) standard for conducting life-cycle assessments, the environmental impacts in making engineered wood flooring were estimated. This study is a follow-up to the CORRIM Report Module G—Life-Cycle Inventory of Solid Strip Hardwood Flooring in the Eastern United States. Life-cycle impact assessment was beyond the scope of this study. Engineered wood flooring is designed to be more dimensionally stable than solid strip wood flooring because it is less susceptible to width shrinkage from increases in moisture. Engineered wood flooring as defined by the National Wood Flooring Association consists of several sheets of solid wood (veneer) bonded together with an adhesive under heat and/or pressure. Although plies having 2, 3, 5, 7, or 9 sheets are available, 3 and 5 are most common. Thicknesses can range from 3/8 to 9/16 in. (9.5 to 14.3 mm). Typical manufacturing includes the following eight unit processes: log yard, debarking and bucking, block conditioning, peeling and clipping, veneer drying, lay up, trimming, sanding, sawing and moulding (profiling), and prefinishing. Inputs and outputs to these unit processes were collected from a survey of manufacturers. The multi-unit process approach is the preferred evaluation method because it helps identify possible process improvements by showing the energy and environmental contribution of each unit process. We determined the environmental impacts based on resource and energy consumption and releases to air, water, and land for making prefinished engineered wood flooring in the eastern United States. Of the five companies contacted in the eastern United States, four companies (comprising four veneer mills and five flooring plants) completed the mill survey. These facilities well represented the industry as a whole, and their manufacturing technology was average. Primary data were collected for the production period January to December 2007. Input data collected included raw materials such as hardwood logs with bark and water, resins, electricity, fossil fuels, prefinishing materials, transportation distances for materials used onsite, and the breakdown of logs into co-products sold (not flooring) such as wood chips and wood fuel burned onsite to produce thermal energy. Allocation of environmental inputs was done on a mass basis because the highest volume product had the highest economic value. This was true for all unit processes. Production unit bases of 1 m3 and 1,000 ft2, were selected to standardize the results to alternative products. Based on surveyed data from the eastern United States, flooring production of 64,840 m2 (73,270 thousand ft2) was found. This was approximately 19% of the total 2007 engineered wood flooring production in the United States of 346,400 m2 (391,400 thousand ft2). No U.S. wood flooring production data were available by individual states. Surveyed mill production exceeded the minimum CORRIM production data requirement of 5%. In addition, this study met the minimum number of product manufacturers (four). Detailed inputs and outputs of unit processes were collected from these manufacturers and weight-averaged to allow modeling in SimaPro 7.1.8 to estimate emissions to air, water, and land. Results also include a carbon balance of the entire process. After developing a mass balance from inputs and outputs, an ovendry density of 656 kg/m3 (40.9 lb/ft3) prefinished engineered wood flooring including wood, resins, and finish (coatings) was estimated. Assuming a specific gravity at 6% MC of 0.656, the density was 695 kg/m3 (43.4 lb/ft3). At 0% MC, the largest component of the flooring is wood (578 kg) and represents 88.2% of the final product mass, resins (65 kg) are 9.8%, and the remaining 2.0% finishing material (13 kg). Hardwood plywood and prefinished engineered wood flooring had wood recoveries of 43% and 35%, respectively. These numbers were determined by the output of wood in the form of plywood as a percentage by weight of the wood input to the manufacturing facilities in the log form (white wood only). Energy consumption and type have significant effects on the environmental performance of all products. In this LCI study, unallocated thermal process energy and electricity consumed was 6,418 MJ/m3 (5.38 million Btu/thousand ft) and 1,113 kWh/m3 (985 kWh/thousand ft2), respectively. Wood fuel at 300 ovendry kg or 6,263 MJ/m3 (5.26 million Btu/thousand ft2) contributed 97.6% of process thermal energy required with the remainder from propane (2.2%) and natural gas (0.2%). Results showed a cumulative allocated value of manufacturing prefinished engineered wood flooring starting with logs at the forest landing to the final product leaving the flooring plant of 22,990 MJ/m3 (19.3 million Btu/thousand ft2) . Unfinished engineered wood flooring showed a cumulative allocated value of 13,600 MJ/m3 (11.4 million Btu/thousand ft2). Tracking emissions is increasingly important in terms of applying proper emission controls. Two different scenarios were created to track emissions and involved system and onsite boundary conditions. First, the total (cumulative) system boundary covers both onsite and off-site emissions for all material and energy consumed. This includes the fuel resources used for the production of energy and electricity and is part of this LCI. Examples of off-site emissions are grid electricity production, transportation of logs to the mill, and fuels produced off-site but used onsite. The onsite system boundary covers emissions developed just at the prefinished engineered wood flooring facilities (i.e., onsite) from the seven unit processes. Environmental impact outputs from SimaPro were allocated to the production of 1 m3 of prefinished engineered wood flooring. A certain portion of the environmental impacts were assigned to the co-products such as wood chips and were not included in the LCI output for prefinished engineered wood flooring. Data quality is considered excellent based on the data collected from the manufacturing facilities. We developed detailed surveys (questionnaires) that were reviewed by a CORRIM representative before distribution. In addition, a CORRIM representative reviewed the SimaPro model for this report. Onsite visits to a veneer mill and flooring plant allowed for provides greater insight into the manufacturing process, thus providing higher quality data. The multi-unit process method allows for unit process improvements to be evaluated more precisely than a system process approach. Modeling data estimated biogenic and fossil CO2 emissions at 623 and 1,049 kg/m3, respectively, and VOCs at 1.04 kg/m3. A cubic meter of prefinished engineered wood flooring stores 1,096-kg CO2 equivalents/m3 as a final product. The following main conclusions are based on the life-cycle inventory: • The amount of carbon stored in prefinished engineered wood flooring exceeds the fossil carbon emissions by about 4%. Therefore, as long as prefinished engineered wood flooring and its carbon stay in products held in end uses, the carbon stored will exceed the fossil carbon emitted in manufacturing. • A trade-off exists between prefinished and unfinished engineered wood flooring. The prefinishing unit process consumes a large amount of electricity from controlling emissions from staining and coating the wood flooring in addition to the prefinishing. As a result, the environmental impact is significantly higher for prefinished engineered wood flooring than for unfinished engineered wood flooring. However, finishing the wood floor after installation in a residential or commercial building (an uncontrolled environment) would result in greater harm to the environment. This harm results from uncontrolled emissions released from the staining and coating process that are now captured or destroyed onsite at the flooring plant. • Burning fuel for energy generates CO2. Nearly all energy burned onsite for manufacturing prefinished engineered wood flooring comes from woody biomass. Burning biomass for energy does not contribute to increasing atmospheric CO2 provided forests are growing and absorbing the emitted CO2 on a sustainable basis. • Increasing onsite wood fuel consumption would reduce fossil greenhouse gases but increase other gases, especially particulate emissions. Particulate matter can be captured prior to release to the atmosphere using commercially available technology but not without increased costs and additional inputs such as electricity.
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The objective of this research is to quantitatively measure and compare the environmental load and construction cost of different structural frame types. Construction cost also accounts for the costs of CO2 emissions of input materials. The choice of structural frame type is a major consideration in construction, as this element represents about 33% of total building construction costs. In this research, four constructed buildings were analyzed, with these having either reinforced concrete (RC) or steel (S) structures. An input-output framework analysis was used to measure energy consumption and CO2 emissions of input materials for each structural frame type. In addition, the CO2 emissions cost was measured using the trading price of CO2 emissions on the International Commodity Exchange. This research revealed that both energy consumption and CO2 emissions were, on average, 26% lower with the RC structure than with the S structure, and the construction costs (including the CO2 emissions cost) of the RC structure were about 9.8% lower, compared to the S structure. This research provides insights through which the construction industry will be able to respond to the carbon market, which is expected to continue to grow in the future.
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