A modeling framework to evaluate sustainability of building construction based on LCSA

Purpose

Life cycle sustainability assessment (LCSA) is a method that combines three life cycle techniques, viz. environmental life cycle assessment (LCA), life cycle costing (LCC), and social life cycle assessment (S-LCA). This study is intended to develop a LCSA framework and a case study of LCSA for building construction projects.

Methods

A LCSA framework is proposed to combine the three life cycle techniques. In the modeling phases, three life cycle models are used in the LCSA framework, namely the environmental model of construction (EMoC), cost model of construction (CMoC), and social-impact model of construction (SMoC). A residential building project is applied to the proposed LCSA framework from “cradle to the end of construction” processes to unveil the limitations and future research needs of the LCSA framework.

Results and discussion

It is found that material extraction and manufacturing account for over 90 % to the environmental impacts while they contribute to 61 % to the construction cost. In terms of social impacts, on-site construction performs better than material extraction and manufacturing, and on-site construction has larger contributions to the positive social impacts. The model outcomes are validated through interviews with local experts in Hong Kong. The result indicates that the performance of the models is generally satisfactory.

Conclusions

The case study has confirmed that LCSA is feasible. Being one of the first applications of LCSA on building construction, this study fulfills the current research gap and paves the way for future development of LCSA.

     

Comparative life cycle assessment and life cycle costing of lodging in the Himalaya

Purpose

The main aim of the study is to assess the environmental and economic impacts of the lodging sector located in the Himalayan region of Nepal, from a life cycle perspective. The assessment should support decision making in technology and material selection for minimal environmental and economic burden in future construction projects.

Methods

The study consists of the life cycle assessment and life cycle costing of lodging in three building types: traditional, semi-modern and modern. The life cycle stages under analysis include raw material acquisition, manufacturing, construction, use, maintenance and material replacement. The study includes a sensitivity analysis focusing on the lifespan of buildings, occupancy rate and discount and inflation rates. The functional unit was formulated as the ‘Lodging of one additional guest per night’, and the time horizon is 50 years of building lifespan. Both primary and secondary data were used in the life cycle inventory.

Results and discussion

The modern building has the highest global warming potential (kg CO_2-eq) as well as higher costs over 50 years of building lifespan. The results show that the use stage is responsible for the largest share of environmental impacts and costs, which are related to energy use for different household activities. The use of commercial materials in the modern building, which have to be transported mostly from the capital in the buildings, makes the higher GWP in the construction and replacement stages. Furthermore, a breakdown of the building components shows that the roof and wall of the building are the largest contributors to the production-related environmental impact.

Conclusions

The findings suggest that the main improvement opportunities in the lodging sector lie in the reduction of impacts on the use stage and in the choice of materials for wall and roof.

     

The assessment of the relevance of building components and life phases for the environmental profile of nearly zero-energy buildings: life cycle assessment of a multifamily building in Italy

Purpose

Since the construction sector is a considerable energy consumer and greenhouse gas (GHG) producer, the EU rules strive to build nearly zero-energy buildings, by reducing the operative energy and yearning for on-site energy production. This article underlines the necessity to go beyond the energy evaluations and move towards the environmental assessment in a life cycle perspective, by comparing the impacts due to building materials and energy production devices.

Methods

We compared the operational energy impacts and those of technologies and materials carrying out a life cycle assessment (LCA; ISO 14040, ISO 14044, EN 15643–2, EN 15978) on a nearly zero-energy building (ZEB), a residential complex with 61 apartments in four buildings, situated near Milan (Italy). We consider all life cycle phases, including production, transport, building site activities, use and maintenance; the materials inventory was filled out collecting data from invoices paid, building site reports, construction drawings and product data sheets. To make the assessment results comparable, we set a functional unit of 1 m² of net floor area in 1 year (1 m²y), upon a lifespan of 100 years. The environmental data were acquired from Ecoinvent 2.2.

Results and discussion

The results highlight the important role of the pre-use and maintenance phases in building life so that in a nearly ZEB, the environmental impacts linked to the use are no longer the major proportion: the pre-use phase accounts for 56 %, while the operative energy is only 31 % of the total. For this reason, if the environmental assessment of the case study was shrunk to the operational consumption, only one third of the impacts would be considered. The consumption of non-renewable resources after 100 years are 193,950 GJ (133.5 kWh/m²y); the GHG emissions are 15,300 t (37.8 kg of CO₂?eq/m²y). In the pre-use phase, structures have the major impacts (50 %) and the load of system components is unexpectedly high (12 %) due to the ambition of on-site energy production.

Conclusions

Paying attention to the operative energy consumption seems to address to only one third of the environmental impacts of buildings: the adoption of LCA as a tool to guide the design choices could help to identify the solution which ensures the lowest overall impact on the whole life, balancing the options of reducing the energy requirements, the on-site production from renewable sources and the limitation of the impacts due to building components (simpler and more durable).

     

Life cycle environmental impacts and costs of beer production and consumption in the UK

Purpose

Global beer consumption is growing steadily and has recently reached 187.37 billion litres per year. The UK ranked 8th in the world, with 4.5 billion litres of beer produced annually. This paper considers life cycle environmental impacts and costs of beer production and consumption in the UK which are currently unknown. The analysis is carried out for two functional units: (i) production and consumption of 1 l of beer at home and (ii) annual production and consumption of beer in the UK. The system boundary is from cradle to grave.

Methods

Life cycle impacts have been estimated following the guidelines in ISO 14040/44; the methodology for life cycle costing is congruent with the LCA approach. Primary data have been obtained from a beer manufacturer; secondary data are sourced from the CCaLC, Ecoinvent and GaBi databases. GaBi 4.3 has been used for LCA modelling and the environmental impacts have been estimated according to the CML 2001 method.

Results and discussion

Depending on the type of packaging (glass bottles, aluminium and steel cans), 1 l of beer requires for example 10.3–17.5 MJ of primary energy and 41.2–41.8 l of water, emits 510–842 g of CO₂ eq. and has the life cycle costs of 12.72–14.37 pence. Extrapolating the results to the annual consumption of beer in the UK translates to a primary energy demand of over 49,600 TJ (0.56 % of UK primary energy consumption), water consumption of 1.85 bn hl (5.3 % of UK demand), emissions of 2.16 mt CO₂ eq. (0.85 % of UK emissions) and the life cycle costs of £553 million (3.2 % of UK beer market value). Production of raw materials is the main hotspot, contributing from 47 to 63 % to the impacts and 67 % to the life cycle costs. The packaging adds 19 to 46 % to the impacts and 13 % to the costs.

Conclusions

Beer in steel cans has the lowest impacts for five out of 12 impact categories considered: primary energy demand, depletion of abiotic resources, acidification, marine and freshwater toxicity. Bottled beer is the worst option for nine impact categories, including global warming and primary energy demand, but it has the lowest human toxicity potential. Beer in aluminium cans is the best option for ozone layer depletion and photochemical smog but has the highest human and marine toxicity potentials.

     

LCA and LCC of the world’s longest pier: a case study on nickel-containing stainless steel rebar

Purpose

Built in 1941, the Progreso Pier was the first concrete structure in the world built with nickel-containing stainless steel reinforcement. The Pier has been in service for over 70 years without any significant repair or maintenance activities. The aim of this study was to understand the environmental and economic implications of selecting nickel-containing stainless steel reinforcement using the Progreso Pier as the case study.

Methods

A combined environmental life cycle assessment (LCA) and life cycle costing (LCC) study was conducted. The analysis considered the potential environmental impacts and the net present cost of the stainless steel reinforced structure from cradle to grave and compared it to the same structure using conventional carbon steel.

Results and discussion

The results indicated that while using stainless steel reinforcement resulted in a marginally higher environmental impact after initial construction, this is offset by the increased service life and, hence, less frequent maintenance and reconstruction activities. Relative to the as-built stainless steel reinforcement design, the environmental impacts of the carbon steel reinforced design are between 69 and 79 % higher over the analysis period. Similar observations were made for the other investigated impact categories. The cost implications of using stainless steel reinforcement show economic benefits that are complementary to the environmental benefits. Similar to the LCA, the service life benefits outweigh the higher unit costs for stainless steel, assuming a discount rate of 0.01 % as the baseline scenario. The carbon steel reinforced design has a net present cost that is 44 % higher than the as-built stainless steel reinforcement design. The crossover point for the two designs occurs at year 50, which corresponds to the reconstruction activity. A sensitivity analysis shows that the results and conclusions are sensitive to the choice in discount rate: Rates 3 % and lower produce net present costs that are lower for the as-built design; rates 4 % and higher produce net present costs that are lower for the alternative design.

Conclusions

The study demonstrates how LCA and LCC are complementary tools that can be used in decision-making for sustainable construction. The Progreso Pier exemplifies the importance of considering the entire life cycle with service life and recycling as well as long-term life cycle impacts of infrastructure projects from an environmental and economic perspective.

     

Comparative LCA of recycled and conventional concrete for structural applications

Purpose

Construction and demolition (C&D) waste recycling has been considered to be a valuable option not only for minimising C&D waste streams to landfills but also for mitigating primary mineral resource depletion. However, the potentially higher cement demand due to the larger surface of the coarse recycled aggregates challenges the environmental benefits of recycling concrete. Furthermore, it is unclear how the environmental impacts depend on concrete mixture, cement type, aggregates composition and transport distances.

Methods

We therefore analysed the life cycle impacts of 12 recycled concrete (RC) mixtures with two different cement types and compared it with corresponding conventional concretes (CC) for three structural applications. The RC mixtures were selected according to laws, standards and construction practice in Switzerland. We compared the environmental impacts of ready-for-use concrete on the construction site, assuming equal lifetimes for recycled and conventional concrete in a full life cycle assessment. System expansion and substitution are considered to achieve the same functionality for all systems.

Results and discussion

The results show clear (～30 %) environmental benefits for all RC options at endpoint level (ecoindicator 99 and ecological scarcity). The difference is mainly due to the avoided burdens associated to reinforcing steel recycling and avoided disposal of C&D waste. Regarding global warming potential (GWP), the results are more balanced and primarily depend on the additional amount of cement needed for RC. Above 22 to 40 kg additional cement per cubic metre of concrete, RC exhibits a GWP comparable to CC. Additional transport distances above 15 km for the RC options do result in environmental impacts higher than those for CC.

Conclusions

In summary, the current market mixtures of recycled concrete in Switzerland show significant environmental benefits compared to conventional concrete and cause similar GWP, if additional cement and transport for RC are limited.

     

The influence of durability and recycling on life cycle impacts of window frame assemblies

Purpose

A set of comparative life cycle assessment case studies were undertaken to explore key issues relating to the environmental impacts of building materials. The case studies explore modeling practice for long-life components by investigating (1) recycled content and end-of-life recycling scenarios and (2) service life and maintenance scenarios. The study uses a window unit frames as the object of comparison, allowing for exploration of multiple materials and assembly techniques.

Methods

Four window frame types were compared: aluminum, wood, aluminum-clad wood, and unplasticized PVC (PVCu). These used existing product life cycle inventory data which included primary frame material, coatings, weather stripping sealants, but not glazing. The functional unit was a window frame required to produce 1 m² of visible glazing, with similar thermal performance over a building lifespan of 80 years. The frames were compared using both the end-of-life and recycled content methods for end-of-life scenarios. The models were also tested using custom-use scenarios.

Results and discussion

Well-maintained aluminum window frames proved to be the least impactful option across all categories, in large part due to the credits delivered from recycling and expectations of long-life. Wood window frames had the least variability associated with maintenance and durability. The global warming potential (GWP) of a moderately maintained aluminum assembly was found to be 68 % less than PVCu and 50 % less than aluminum-clad wood. Using a long-life scenario, wood windows were found to have a 7 % lower GWP than the long-life scenario for aluminum-clad woods. Moderately and well-maintained aluminum windows require less energy to be produced and maintained over their lifetime than any of the wood scenarios. Expectations of service life proved to be the most important factor in considering environmental impact of frame materials.

Conclusions

The research shows significant gaps in available data—such as average realized life expectancies of common building components—while further underscoring that recycling rates are a driving factor in the environmental impact of aluminum building products. A modeling shift from the recycled content method to the end-of-life recycling method should promote goals of material recovery over pursuit of material with high recycled content. Hybrid methods, such as the use of Module D, may bridge the divide between these two approaches by providing due credit for use of recycled material, while supporting a design for recycling ethos. Further research is needed on how design and construction decisions affect collection and recovery rates in practice.

     

The methodology and results of using life cycle assessment to measure and reduce the greenhouse gas emissions footprint of “Major Events” at the University of Arizona

Purpose

In 2012 and 2013, the University of Arizona’s Office of Sustainability conducted environmental life cycle assessments of two Homecoming events that drew 60,000 attendees each. Based on reviews of published literature, this is the first time that a process-based life cycle assessment has been conducted for an event of this size. This study contributes to the small but growing field of research using life cycle assessment to track the environmental impacts of events.

Methods

The assessments at The University of Arizona considered the environmental impact of food, materials, waste, travel, and lodging. The effects of these components of Homecoming weekend were evaluated in terms of nine different categories. However, this paper focuses on greenhouse gas emissions. The data collection process for these assessments was completed by student observers and supplemented with information provided by university departments, event organizers, and survey responses from attendees. Data were analyzed using SimaPro Life Cycle Assessment software and using data from the EcoInvent database. Based on the results of the 2012 study, initiatives were put into place for 2013 that were designed to reduce the environmental impact of the subsequent Homecoming event.

Results and discussion

The results show that the total impact of Homecoming 2012 was an estimated 2400 metric tons of CO₂-eq, whereas the impact of Homecoming 2013 was an estimated 1900 metric tons of CO₂-eq, a 19 % decrease year over year. Data were analyzed in terms of carbon dioxide emissions in both years. Travel made up the majority of the environmental impact (82.04 % in 2012 and 77.77 % in 2013), followed by accommodations (17.5 % in 2012 and 19.31 % in 2013), with energy, materials, and food having almost negligible impacts (0.46 % in 2012 and 2.92 % in 2013). While there had been noticeable changes in the measured impact of food and energy between 2012 and 2013, the significant impact of travel overshadowed all other impact categories in terms of greenhouse gas emissions, making these changes less noticeable. Analysis of each of these categories of impact helped to establish best practices for mitigating the impact of events on a category-by-category basis.

Conclusions

This study introduces a framework for assessing impacts of a large university event while also highlighting ways to reduce impacts. The initiatives implemented in 2013 to reduce impacts of large-scale events can be informative to others working to reduce emissions at large events. Additional recommendations to reduce impacts of large events are provided.

     

Life cycle assessment and cost analysis of residential buildings in south east of Turkey: part 1—review and methodology

Purpose

Buildings are responsible for more than 40 % of global energy used, and as much as 30 % of global greenhouse gas emissions. In order to quantify the energy and material inputs and environmental releases associated with each stage of construction sector, life cycle energy, greenhouse gas emissions, and cost analysis of contemporary residential buildings have been conducted within two parts.

Methods

This paper is the first part of the study which includes the literature review and methodology used for such a comprehensive analysis. It was determined that there are three basic methods used in life cycle analysis: process analysis, input–output (I–O) analysis, and hybrid analysis. In this study, Inventory of Carbon and Energy (ICE) is used for the calculation of primary energy requirements and greenhouse gas emissions. The second part of this study is about the application of the methodology which considers two actual buildings constructed in Gaziantep, Turkey.

Results and discussion

The proposed research focused on building construction, operating, and demolition phases. Energy efficiency, emission parameters, and costs are defined for the building per square meter basis. It is seen that the primary energy use and emissions of residential buildings around the world falls in the range of about 10 to 40 GJ/m² and 1–10 t CO₂/m² respectively.

Conclusions

The literature survey demonstrates that there are limited number of studies about life cycle cost assessment (LCCA) of residential buildings in the world. It was decided to use the ICE database as it is one of the most comprehensive databases for building materials, globally. The results of the study show that minimizing energy, material, and land use by considering potential impacts to the environment on a life cycle basis are the basic steps in designing an energy-efficient and environmental-friendly building.

     

Environmental profile analysis of particleboard production: a study in a Pakistani technological condition

Purpose

Particleboard is a composite panel comprising small pieces of wood bonded by adhesives. The particleboard industry is growing in Pakistan, but there is little information on the environmental impacts associated with this product. Therefore, the aim of this study was to develop a life cycle assessment of particleboard manufactured in Pakistan and to provide suggestions to improve its environmental profile. The study covers energy use and associated environmental impacts of raw materials and processes during particleboard manufacture in the year 2015–2016.

Methods

The study uses a cradle-to-gate (distribution center) life cycle assessment approach. The reference unit for this study was 1.0 m³ of finished, uncoated particleboard. Primary data from the particleboard mill surveys were combined with secondary database information and modeled using CML 2000 v.2.05 methodology and a cumulative exergy demand indicator present in the SimaPro v.8.3 software.

Results and discussion

The results reveal that urea formaldehyde resin, transportation of raw materials, and finished product distribution had the highest contribution to all the environmental impact categories evaluated. Heavy fuel oil and natural gas consumption was responsible for abiotic depletion, photochemical oxidation, ozone layer depletion, and marine aquatic ecotoxicity impacts. The rotary dryer and hot press were the most important sectors in terms of emissions from the manufacturing process. The total cumulative exergy demand required for manufacturing of 1.0 m³ particleboard was 15,632 MJ-eq, with most of the energy usage associated with non-renewable, fossil fuel sources. A sensitivity analysis was conducted for a reduction in the quantity of urea formaldehyde resin consumed and freight transport distances.

Conclusions

The results indicated that reducing the urea formaldehyde resin use and freight distances could greatly decrease environmental impacts. Most of the surveyed mills did not have emissions control systems, and most of the mills exceed the limits set by the National Environmental Quality Standards of Pakistan. Environmental impact improvements might be attained by reducing quantity of urea formaldehyde resin and transportation freight distances and by installing pollution control devices.

     

Estimation of greenhouse gas emissions from sewer pipeline system

Purpose

The aim of this study was to estimate the total greenhouse gas (GHG) emissions generated from whole life cycle stages of a sewer pipeline system and suggest the strategies to mitigate GHG emissions from the system.

Methods

The process-based life cycle assessment (LCA) with a city-scale inventory database of a sewer pipeline system was conducted. The GHG emissions (direct, indirect, and embodied) generated from a sewer pipeline system in Daejeon Metropolitan City (DMC), South Korea, were estimated for a case study. The potential improvement actions which can mitigate GHG emissions were evaluated through a scenario analysis based on a sensitivity analysis.

Results and discussion

The amount of GHG emissions varied with the size (150, 300, 450, 700, and 900 mm) and materials (polyvinyl chloride (PVC), polyethylene (PE), concrete, and cast iron) of the pipeline. Pipes with smaller diameter emitted less GHG, and the concrete pipe generated lower amount of GHG than pipes made from other materials. The case study demonstrated that the operation (OP) stage (3.67 × 10⁴ t CO₂eq year^?1, 64.9%) is the most significant for total GHG emissions (5.65 × 10⁴ t CO₂eq year^?1) because a huge amount of CH₄ (3.51 × 10⁴ t CO₂eq year^?1) can be generated at the stage due to biofilm reaction in the inner surface of pipeline. Mitigation of CH₄ emissions by reducing hydraulic retention time (HRT), optimizing surface area-to-volume (A/V) ratio of pipes, and lowering biofilm reaction during the OP stage could be effective ways to reduce total GHG emissions from the sewer pipeline system. For the rehabilitation of sewer pipeline system in DMC, the use of small diameter pipe, combination of pipe materials, and periodic maintenance activities are suggested as suitable strategies that could mitigate GHG emissions.

Conclusions

This study demonstrated the usability and appropriateness of the process-based LCA providing effective GHG mitigation strategies at a city-scale sewer pipeline system. The results obtained from this study could be applied to the development of comprehensive models which can precisely estimate all GHG emissions generated from sewer pipeline and other urban environmental systems.

     

Environmental impact trade-offs in building envelope retrofit strategies

Purpose

The use of high levels of thermal insulation is a common practice towards reducing the energy consumption of the existing building stock; however, the embodied burdens associated with the additional insulation material are usually not taken into account and questions regarding the risks of over-specifying the insulation levels have been emerging, particularly for mild climate regions. This article addresses the issue presenting an integrated approach that combines life cycle assessment and thermal dynamic simulation to assess alternative retrofit strategies for the roof and exterior walls of two dwellings (from the beginning of the twentieth century), in the historic city center of Coimbra, Portugal. A comprehensive analysis of alternative insulation thicknesses (no insulation, 40, 80, and 120 mm of expanded polystyrene) was made to identify optimal thickness levels minimizing life cycle (LC) environmental impacts for a single-family house and an apartment.

Methods

Embodied and operational impact trade-offs were calculated for six impact categories: climate change, ozone depletion, terrestrial acidification, freshwater eutrophication, marine eutrophication, and non-renewable primary energy. The operational energy was calculated using a dynamic thermal modeling software (EnergyPlus). The functional unit selected for this study was 1 m² of living area over a period of 50 years.

Results and discussion

The single-family house embodied impacts account for 26–57 % of total LC impacts. For insulation thicknesses larger than 80 mm, the embodied impacts are greater than operational impacts. For the apartment, embodied impacts account for 25–49 % of total LC impacts. The environmental benefits of additional insulation are very low (<3 %) for thicknesses of more than 80 mm for both roof and exterior walls. For thicknesses above the tipping point (where total LC impacts are minimized), the marginal impacts of additional insulation are higher than the benefits. The results for the apartment show that optimal insulation thicknesses (LC tipping point) range from 30 to 40 mm for the roof and from 60 to 80 mm for the exterior walls. The LC tipping point for the single-family house is achieved by combining 80–100 mm of roof insulation with 60–80 mm of exterior wall insulation.

Conclusions

Extra insulation levels in temperate climates can lead to higher embodied impacts, without significant reduction in operational impacts, which can result in higher total LC impacts. The results show that a tipping point can be identified, and recommendations are provided for the roof and exterior wall retrofits of buildings from the beginning of the twentieth century.

     

Corneal Collagen Cross-Linking for the Management of Mycotic Keratitis

Purpose

To evaluate the efficiency of corneal collagen cross-linking (CXL) in addition to topical voriconazole in cases with mycotic keratitis.

Design

Retrospective case series in a tertiary university hospital.

Participants

CXL was performed on 13 patients with mycotic keratitis who presented poor or no response to topical voriconazole treatment.

Methods

The clinical features, symptoms, treatment results and complications were recorded retrospectively. The corneal infection was graded according to the depth of infection into the stroma (from grade 1 to grade 3). The visual analogue scale was used to calculate the pain score before and 2 days after surgery.

Main Outcome Measures

Grade of the corneal infection.

Results

Mean age of 13 patients (6 female and 7 male) was 42.4 ± 17.7 years (20–74 years). Fungus was demonstrated in culture (eight patients) or cytological examination (five patients). Seven of the 13 patients (54%) were healed with topical voriconazole and CXL adjuvant treatment in 26 ± 10 days (15–40 days). The remaining six patients did not respond to CXL treatment; they initially presented with higher grade ulcers. Pre- and post-operative pain score values were 8 ± 0.8 and 3.5 ± 1, respectively (p < 0.05).

Conclusions

The current study suggests that adjunctive CXL treatment is effective in patients with small and superficial mycotic ulcers. These observations require further research by large randomized clinical trials.

     

Method and application of characterisation of life cycle impact data of construction materials using geographic information systems

Purpose

This research presents a methodology to characterize life cycle impact data (LCIA) of alternative construction materials outside of the European context.

Methods

This methodology was based on the characterization of data and life cycle assessment (LCA) using geographic information systems (GIS), which has been proposed as an effective alternative for this purpose. The data were characterized at three levels: global, represented by different production efficiency of materials; regional, represented by the type of electricity mix used in the production and the national transport at the country level; and local, represented by external factors, such as seismic and wind risk zones at the city level. A comparative LCA was used as case study to test the methodology. The functional unit for the LCA was defined as an 18 m² core shelter unit consisting of structural elements only. The bill of materials for five designs were calculated, each using a distinctive construction material: bamboo, brick, concrete hollow block, ferro-cement panels, and soil-stabilised bricks. The contributions’ variability and uncertainty analysis were used to validate the consistency of the results. The effect of the external constraints (earthquakes and wind) were analysed, and the environmental impact over the whole life cycle was assessed. Five house designs were calculated in twenty locations based on three levels of production efficiency and three transport distance ranges for each country.

Results and discussion

The results of the bamboo, concrete hollow block and ferro-cement houses overlapped and changed depending on the construction materials’ transport distance. Therefore, the level of impact of an average bamboo house can also be achieved by a high-performance block or ferro-cement house. The results showed that in most cases, the buildings with high technical performance can be achieved with low environmental impacts.

Conclusions

The use of GIS enables the development of characterized LCIA data for construction materials and buildings with a high degree of consistency. Moreover, the proposed approach was able to accurately represent the range of production practices used outside Europe. Finally, the use of the proposed methodology allows for the assessment of building in the early stages of design when uncertainty is at its highest, thereby identifying the improvement potential of each design and recognising the structural needs in specific locations.

     

Life cycle assessment-based selection of a sustainable lightweight automotive engine hood design

Purpose

This study presents a life cycle assessment (LCA)-based sustainable and lightweight automotive engine hood design and compares the life cycle energy consumption and potential environmental impacts of a steel (baseline) automotive engine hood with three types of lightweight design: advanced high strength steel (AHSS), aluminum, and carbon fiber.

Methods

A “cradle-to-grave” LCA including the production, use, and end-of-life stages is conducted in accordance with the ISO 14040/14044 standards. Onsite data collected by Chinese automotive companies in 2015 are used in the assessment. The Cumulative Energy Demand v1.09 method is applied to evaluate cumulative energy demand (CED), and the International Panel on Climate Change 2013 100a method is used to estimate global warming potential (GWP 100a).

Results and discussion

Among the different lightweight designs for the engine hood, the aluminum design is the most sustainable and has the lowest CED and GWP (100a) from a life cycle perspective, which is based on a lifetime driving distance of approximately 150,000 km. In addition, the AHSS design is also sustainable and lightweight. The carbon fiber design results in higher CED and GWP (100a) values than the steel (baseline) design during the life cycle but results in the largest CED and GWP (100a) savings through waste material recycling. The AHSS design exhibits the best break-even distance based on CED and GWP (100a) within 150,000 km.

Conclusions

Sensitivity analysis results show that the lifetime driving distance and material recycling rate have the largest impacts on the overall CEDs and GWPs of the three lightweight designs.

     

Vehicle lightweighting through the use of molybdenum-bearing advanced high-strength steels (AHSS)

Purpose

The past two decades have seen growing pressure on vehicle manufacturers to reduce the environmental impact of their vehicles. One effective way to improve fuel efficiency and lower tailpipe emissions is to use advanced high-strength steels (AHSS) that offer equal strength and crash resistance at lower mass. The present study assesses the life cycle environmental impacts of two steel grades considered for the B-pillar in the Ford Fusion: A press-hardened boron steel design as used in the previous model of the vehicle and a hydroformed component made from a mix of the molybdenum-bearing dual phase steels DP800 and DP1000.

Methods

Information related to the component masses and grades was provided by Ford. Process models for the steelmaking process, finishing, forming, vehicle use and end of life were created in the GaBi LCA software tool. Sensitivity analyses were conducted on the impact of the hydroforming process for the new component, for which only proxy data were available and on the mix of DP800 and DP1000 in the B-pillar. Results have been presented for the environmental impact categories deemed most relevant to vehicle use.

Results and discussion

The life cycle assessment showed that the new DP800/DP1000 B-pillar design has a lower impact for the environmental impact categories assessed. Overall, the global warming potential (GWP) of the new DP800/DP1000 design was 29 % lower than the boron steel design over the full life cycle of the vehicle. The use phase was found to be the major source of environmental impacts, accounting for 93 % of the life cycle GWP impact. The 4 kg weight saving accounts for the majority of the difference in impacts between the two B-pillar designs. Impacts from manufacturing were also lower for the new design for all of the impact categories assessed despite the higher alloy content of the steel. A sensitivity analysis of the hydroforming process showed that even if impacts from forming were 100 % greater than for press hardening, the GWP from production of the new B-pillar design would still be lower than the boron steel version.

Conclusions and recommendations

The molybdenum-bearing DP1000/DP800 B-pillar was found to have lower life cycle and production impacts than the previous boron steel design. The assessment indicates that significant improvements in the environmental impacts associated with the body structure of vehicles could be made through the increased use of AHSS in vehicles without compromising crash performance.

     

Life cycle assessment of ocean energy technologies

Purpose

Oceans offer a vast amount of renewable energy. Tidal and wave energy devices are currently the most advanced conduits of ocean energy. To date, only a few life cycle assessments for ocean energy have been carried out for ocean energy. This study analyses ocean energy devices, including all technologies currently being proposed, in order to gain a better understanding of their environmental impacts and explore how they can contribute to a more sustainable energy supply.

Methods

The study followed the methodology of life cycle assessment including all life cycle steps from cradle to grave. The various types of device were assessed, on the basis of a functional unit of 1 kWh of electricity delivered to the grid. The impact categories investigated were based on the ILCD recommendations. The life cycle models were set up using detailed technical information on the components and structure of around 180 ocean energy devices from an in-house database.

Results and discussion

The design of ocean energy devices still varies considerably, and their weight ranges from 190 to 1270 t, depending on device type. Environmental impacts are closely linked to material inputs and are caused mainly by mooring and foundations and structural components, while impacts from assembly, installation and use are insignificant for all device types. Total greenhouse gas emissions of ocean energy devices range from about 15 to 105 g CO₂-eq. kWh^?1. Average global warming potential for all device types is 53?±?29 g CO₂-eq. kWh^?1. The results of this study are comparable with those of other studies and confirm that the environmental impacts of ocean energy devices are comparable with those of other renewable technologies and can contribute to a more sustainable energy supply.

Conclusions

Ocean energy devices are still at an early stage of development compared with other renewable energy technologies. Their environmental impacts can be further reduced by technology improvements already being pursued by developers (e.g. increased efficiency and reliability). Future life cycle assessment studies should assess whole ocean energy arrays or ocean energy farms.

     

Environmental performance of three innovative calcium carbonate-based consolidants used in the field of built cultural heritage

Purpose

In this study, the environmental performance of three newly developed materials for the conservation of built Cultural Heritage is preliminary evaluated by means of life cycle assessment (LCA). Although LCA has been adopted since many years in many fields, including the construction industry, still it is barely used the field of the Cultural Heritage conservation. Therefore, this paper aims to put a step forward to a wider use of the method for a more sustainable conservation of built heritage.

Methods

Cradle-to-gate approach was applied, which includes activities beginning with production of constituent and ancillary materials and concluding with the manufacturing of the product and its packaging. The functional unit was the production of 1 kg of the consolidant stored in a canister and ready to use. Ecoinvent database was used for the life cycle inventory of chemicals. This database was also taken into account to evaluate impacts related with energy (electricity) needs during manufacturing of the consolidants and production of polyethylene canisters (packaging material). The IMPACT 2002+ method was used to select the impact categories.

Results and discussion

The consolidants under investigation are calcium acetoacetate and two calcium alkoxides (calcium ethoxide and calcium isopropoxide). In the case of calcium acetoacetate consolidant, the highest environmental impact is related to the use of acetone dicarboxylic acid as raw material. Manufacturing process of the final product is not an energy-demanding process; hence, it is regarded as relatively clean from the environmental point of view. In the case of calcium ethoxide and calcium isopropoxide nanosuspensions, the innovative materials just recently developed for conservation purpose, manufacturing has been performed and optimized at a kg/lab scale; therefore, the results must be considered provisional. The two calcium alkoxides nanosuspensions show a relatively high environmental footprint that reflect the high consumption of ancillary materials, i.e. solid CO₂ used to cool down the reaction and liquid ammonia as catalyst, currently released in the atmosphere.

Conclusions

The environmental footprint of calcium acetoacetate is relatively low showing that 1 kg of the consolidant is associated to 0.32 kg of CO₂ equivalent emissions. In the case of two calcium alkoxides nanosuspensions, the global warming impact amounts to 198 kg (calcium ethoxide, 1 kg) and 132 kg (calcium isopropoxide, 1 kg) of CO₂ equivalent emissions. Given the planned optimization of the industrial production currently under investigation, the environmental footprint of the two calcium alkoxides nanosuspensions is expected to reduce between 60 and 85%.

     

Azoospermia in rabbits following an intravas injection of Vasalgel ™

Background

Vasectomy is currently the only long-acting contraceptive option available for men, despite increasing demand and potentially significant positive impacts on human health of additional male contraceptive options. Vasalgel ? is a high molecular weight hydrogel polymer being developed as a non-hormonal long-acting reversible male contraceptive. Vasalgel consists of styrene-alt-maleic acid dissolved in dimethyl sulfoxide, which is distinct from styrene-alt-maleic anhydride materials previously studied.

Methods

The goal of the study was to determine the contraceptive efficacy of two test articles with different levels of styrene maleic acid (100 %, and 80 % acid/20 % anhydride). The test articles were injected bilaterally in the vasa deferentia of mature male rabbits. Post-implantation analyses of semen parameters were completed over a 12 month period and compared to baseline measures of sperm concentration, motility and forward progression.

Results

Both test articles were effective in blocking the passage of spermatozoa through the vasa deferentia in the 12 subjects completing the study. A significant decrease in sperm concentration occurred following implantation of the test material, with no measurable sperm concentration except for a few samples in one animal that were markedly oligospermic. Vasalgel produced a rapid onset of azoospermia, with no sperm in semen samples collected as early as 29–36 days post-implantation, and was durable over a 12 month period.

Conclusion

This study indicated that Vasalgel is an effective non-hormonal long-acting male contraceptive in a rabbit model.

     

Life cycle assessment of nickel products

Purpose

To support the data requirements of stakeholders, the Nickel Institute (NI) conducted a global life cycle impact assessment (LCIA) to show, with indicators, the potential environmental impacts of the production of nickel and ferronickel from mine to refinery gate. A metal industry wide agreed approach on by-products and allocation was applied.

Methods

Nine companies, comprising 19 operations, contributed data, representing 52 % of global nickel metal production and 40 % of global ferronickel production. All relevant pyro- and hydrometallurgical production routes were considered, across most major nickel-producing regions. Data from Russia, the biggest nickel-producing nation, was included; the Chinese industry did not participate. 2011 was chosen as reference year for data collection. The LCIA applied allocation of impacts of by-products using both economic and mass allocations. A sensitivity analysis was conducted to further understand the relevance and impact of the different allocation approaches.

Results and discussion

The primary extraction and refining steps are the main contributors to primary energy demand (PED) and global warming potential (GWP), contributing 60 and 70 % to the PED for the production of 1 kg class I nickel and 1 kg nickel in ferronickel, respectively, and over 55 % of the GWP for both nickel products. The PED for 1 kg class 1 nickel was calculated to be 147 MJ, whilst the PED for 1 kg nickel in ferronickel was calculated to be three times higher at 485 MJ. The main factors influencing energy demand in the metallurgical processes are ore grade and ore mineralogy. Sulphidic ore is less energy intensive to process than oxidic ore. Eighty-six percent of the production volume from class 1 nickel producers, in this study, is from sulphidic ore. All ferronickel was produced from oxidic ore. The LCIA results, including a sensitivity analysis of the impact of producers with higher and lower PED, reflect the influence of the production route on energy demand and on environmental impact categories.

Conclusions

Conformant to relevant ISO standards, and backed-up with a technical and critical review, this LCIA quantifies the environmental impacts associated with the production of the main nickel products. With this study, a sound background dataset for downstream users of nickel has been provided. The Nickel Institute aims to update their data in the coming years to reflect upon changes in technology, energy efficiency, and raw material input.