An optimized solution for retrofitting building façades: Energy efficiency and cost-benefit analysis from a life cycle perspective

The study aims to conduct a comprehensive cost-benefit analysis (CBA) for incremental energy star ratings in Melbourne and Perth by upgrading the thermal performance of the building façade. CBA is performed over 20, 40, and 60 years by considering the refurbishment of an existing building façade or a newly constructed house to ensure the highest energy efficiency at the lowest reasonable cost. The hybrid approach of using a dynamic energy simulation tool (FirstRate5) and @RISK optimizer provides a feasible solution for obtaining a specific star rating. This study shows energy saving costs can offset the additional investment of insulation levels and energy-efficient glazings. However, life cycle energy savings are minimized after a certain point of supplementary yield insulations, such as ceilings R(6) and walls R(3). Hence the results are evaluated in terms of financial appraisals, such as net present value (NPV), benefit-cost ratio (BCR), internal rate of return (IRR), and other indicators for incremental star-rated designs. The results of the financial appraisals recommend upgrading the obligatory star rating from 6-star to 8-star is a cost-effective solution irrespective of climate and time horizon. Sensitivity indices of design variables exhibit the significance of functionality and cost implications in the established energy rating scheme. Possible economic recession (at > 7%) due to COVID and the Ukraine war, the investment coefficient (r ≤ −0.56) with NPV increases significantly against energy savings cost (r ≥ 0.8). Given the present energy rating scheme, these findings provide an exhaustive perception of policy implications.

Circular Economy of Construction and Demolition Wood Waste—A Theoretical Framework Approach

A considerable amount of construction and demolition wood waste (CDWW) is generated, mostly landfilled, contributing to severe environmental effects. The management of CDWW is a significant challenge as it is a hazardous contaminated waste. In this context, the circular economy (CE) concept is a solution as it comprises waste minimisation and efficient recovery of resources. Although much research is found in the literature on CDWW end-of-life management, research on CE implementation considering every life cycle stage is still scarce. In this review, we endeavour to integrate CE in CDWW to identify the waste management strategies involved in the life cycle phases. The databases were searched from 2009 to 2020 and were analysed using CiteSpace version 5.7.R1 software. Forty-nine articles were identified, and the six life cycle stages were explored. The analysis shows that CE for wood waste is essential and has greater growth potential. While the LCA studies are limited to environmental viewpoints, combining economic and social perspectives is necessary for sustainable development. Overall, based on the research findings, a theoretical framework was proposed. This study, as a consequence, promotes the application of recycled wood into multiple valuable products and thus encourages waste management to boost CE and sustainability.

A Sustainable Approach on the Utilisation of COVID-19 Plastic Based Isolation Gowns in Structural Concrete

Single-use isolation gowns have become an important practice across medical centres, testing sites, and emergency rooms since the onset of the Coronavirus pandemic;within the later months of 2019. Although reusable isolation gowns have proved beneficial, 80% of frontline centres opt for disposable isolation gowns, increasing the demand for plastic-based personal protective equipment (PPE) and the environmental strain from excess waste in landfills. This research aims to explore the practicability of using plastic-based isolation gowns in structural concrete to scale back the quantity of pandemic-generated waste ending up in landfills. The shredded isolation gowns were added to aggregates at 0.01%, 0.02%, and 0.03% of the volume of concrete. The effects of various concentrations of shredded isolation gowns on the mechanical properties of the concrete were investigated through a series of experiments alongside an SEM-EDS analysis. Results demonstrate an enhanced bridging effect between the cement matrix and shredded isolation gowns, allowing for the steady trend of improved mechanical properties with increases of 15.5%, 20.6%, and 11.73% across compressive strength, flexural strength, and the modulus of elasticity, respectively.

Ventilating aged-care center based on solar chimney: Design and theoretical analysis.

Natural ventilation is considered the first suggestion for COVID-19 prevention in buildings by the World Health Organization (WHO). Solar chimney's viability in aged care centers or similar facilities was analyzed numerically and theoretically. A new solar chimney design was proposed to reduce the cross-infection risk of COVID-19 based on an airflow path through window, ceiling vent, attic, and then chimney cavity. Solar chimney performance, quantified by the natural ventilation rate, presented power function with window area, ceiling vent area, cavity height, and solar radiation. The ceiling vent is suggested to be closer to the corridor to enhance the performance and ventilation coverage of the room. A cavity gap of 1.0 m is recommended to balance the ventilation performance and construction cost. A theoretical model was also developed for aged care centers with multiple rooms and a joint attic. Its predictions obey reasonably well with the numerical results. Solar chimney's viability in aged care center is confirmed as a 7.22 air change per hour (ACH) ventilation can be achieved even under a low solar radiation intensity of 200 W/m2, where its performance fulfills the minimal ventilation requirement (i.e., 6 ACH) suggested by the WHO for airborne infection isolation rooms. This study offers a new design and a guideline for the future implementation of solar chimney in aged care centers or similar facilities.

The challenges confronting the growth of sustainable prefabricated building construction in Australia: Construction industry views

The construction industry has played a huge role in sustaining the economy of Australia during the ongoing Covid-19 pandemic. However, construction activities tend to be limited due to the restrictions on travel, transport, and workforce availability which in turn affects the lack of materials and workforce for construction. On the other hand, the prefabricated construction method is known to provide a sustainable solution to reduce the labour and material demand. However, prefabricated construction methods are less preferred over traditional construction in Australia. This is due to the lack of knowledge on the benefits, limitation, design and construction of the prefabricated construction. Therefore, in this study, the authors have conducted a survey to identify the construction industry views on the prefabricated construction in terms of sustainability, technical, cultural, economic, practical and other aspects. A total of 310 construction professionals responded, and the data were analysed using both qualitative (thematic) and quantitative (Severity index) analyses. Results revealed that reduced construction time, high levels of quality control, and reduced on-site noise and disruption were the major benefits when using prefabricated construction compared to traditional construction. The restrictions and limitations of transport;reduced on-site design flexibility;and shortage of specialised workforce hindered the growth of prefabricated construction. These survey results also highlighted that production and manufacturing of prefabricated construction are not affected significantly by the Covid-19 pandemic. Furthermore, significant amount of traditional, residential and commercial construction projects were replaced by prefabricated construction during Covid-19 pandemic, suggesting a future growth in prefabricated construction in Australia.

Application of COVID-19 single-use shredded nitrile gloves in structural concrete: Case study from Australia.

The use of single-use nitrile gloves has been on a sharp incline since the Coronavirus pandemic first started in late 2019. This led to a significant increase in the generation of this clinical waste that requires various recycling solutions to reduce its environmental impact from disposal or incineration. This paper explores its application in structural concrete by adding shredded nitrile gloves at 0.1%, 0.2%, and 0.3% of the volume of concrete. The compressive strength, modulus of elasticity, ultrasonic pulse velocity, and SEM-EDS analysis were undertaken to ascertain the effect of different concentrations of shredded nitrile gloves on the mechanical properties, quality of concrete, and its bond performance with the cement matrix. The results demonstrate that the inclusion of up to 0.2% of shredded nitrile gloves can provide ~22% improvement in the compressive strength of blended concrete composites at 28-days of curing. In comparison, the inclusion of 0.3% of shredded nitrile gloves shows improvements of ~20% in compressive strength at 28-days. The SEM-EDS analysis shows a very good bond formation between the nitrile rubber and the cement matrix with no gap identified in the interfacial transition zone (ITZ).

Preliminary evaluation of the feasibility of using polypropylene fibres from COVID-19 single-use face masks to improve the mechanical properties of concrete.

With the ongoing global pandemic due to Coronavirus (COVID-19), the use of personal protective equipment (PPE), specifically single-use surgical masks, have been on a sharp incline. Currently, many countries are experiencing second and third waves of COVID-19 and as such have resorted to making face masks a mandatory requirement. The repercussions of this have resulted in millions of single-use face masks being discharged into the environment, washing up on beaches, floating beneath oceans and ending up in vulnerable places. The global pandemic has not only affected the economy and health of the world's population but now is seriously threatening the natural environment. The main plastic in single-use face masks is polypropylene which in landfill can take more than 25 years to break down. This paper explores an innovative way to use pandemic waste in concrete construction with the main focus on single-use face masks. Single-use masks have been cut-up by first removing the ear loops and inner nose wire to size and spread throughout five different mix designs to explore the possible benefits and uses within concrete. The masks were introduced by volume at 0% (control), 0.10%, 0.15%, 0.20% and 0.25% with testing focusing on compressive strength, indirect tensile strength, modulus of elasticity and ultrasonic pulse velocity to test the overall quality of the concrete. The introduction of the single-use face masks led to an increase in the strength properties of the concrete samples, as well as an increase in the overall quality of the concrete. However, beyond 0.20%, the trend of increasing strength began to decrease.