Mohd Firrdhaus Mohd Sahabuddin

Earth has been used as a construction material for thousands of years and is now receiving renewed attention as a building material with minimal environmental effects. This study explores the development of earth-based construction, with particular attention to rammed earth, from sustainability, engineering, durability, and practical application perspectives. Earth construction techniques, including rammed earth, cob construction, compressed earth blocks, adobe, and wattle and daub, are discussed together with their social, environmental, technical, and economic benefits. In addition, this study reviews international standards and guidelines related to material properties, soil selection, durability, structural design, energy performance, and indoor environmental quality. The results show that earth-based materials can reduce embodied energy, transportation demand, carbon emissions, and construction waste while offering high indoor comfort, long service life, sufficient thermal mass, and recyclability. Although earth-based construction has several advantages, its wide application is still limited because of low tensile capacity, construction limitations, moisture-related deterioration, cracking, and varying soil properties. Furthermore, projects from Malaysia, Japan, and China prove that careful material selection, modern compaction methods, and proper structural detailing can substantially increase the performance of rammed earth. The overall performance of rammed earth mainly relies on consistent design standards, durable low-carbon stabilization methods, and improved structural and seismic performance.

Buildings account for a substantial share of global energy consumption, much of which is associated with heating, ventilation, and air conditioning systems for indoor climate control. Passive strategies rooted in historical architectural typologies, such as courtyard buildings, offer potential to enhance energy efficiency and indoor comfort. This Preferred Reporting Items for Systematic Reviews and Meta-Analyses-guided systematic review analyzed 83 peer-reviewed studies published between January 2014 and September 2025. Using thematic content analysis, we synthesized evidence on how key configuration parameters (orientation, aspect ratio, height-to-depth ratio, window-to-wall ratio, and length-to-width ratio) affect three performance domains—thermal comfort, energy efficiency, and daylight performance—across major climate zones (tropical, hot-arid, temperate, and continental). The literature is concentrated in hot-arid and temperate climates, whereas tropical and continental zones remain comparatively underexplored. Orientation and aspect ratio were the most frequently investigated parameters, and simulation-based methods predominated. The review also identifies critical gaps in theoretical grounding, methodological standardization, and empirical diversity. Most of the studies show limited interdisciplinary integration, minimal consideration of occupant/population differences, and restricted real-world applicability, particularly for public and institutional buildings. By consolidating global evidence, this review further proposes a performance-oriented framework to interpret and advance Chinese courtyard architecture, including siheyuan, sanheyuan, and tulou, across diverse climatic and urban–rural contexts. These findings highlight priorities for China-focused research, including multi-objective performance assessment, empirical validation, and climate-sensitive design strategies. Overall, the review provides actionable insights for architects, urban designers, and policymakers seeking to advance climate-adaptive and context-responsive architectural practice.

Rapid urbanization in Kuala Lumpur has intensified the Urban Heat Island (UHI) effect, compromising thermal comfort and increasing environmental stress. This study examines how urban morphology and passive building design influence microclimatic conditions in three contrasting areas: Kampung Baru (suburban), Bukit Bintang (dense urban), and KLCC Park (green zone). Field measurements of air temperature, relative humidity, wind speed, and PM2.5 were collected using mobile equipment. Results show that compact urban districts experience elevated temperatures and reduced ventilation, while vegetated and water-adjacent areas provide notable cooling. Findings are evaluated against thermal comfort benchmarks (ASHRAE 55; MS1525), underscoring the need for climate-responsive urban planning. Mitigation strategies include expanding green infrastructure, applying reflective materials, and strengthening passive design features to enhance thermal comfort in high-density tropical cities. The study acknowledges limitations of short-term mobile measurements and recommends future research involving long-term monitoring and simulation modeling to strengthen understanding of UHI dynamics.

Numerous studies have discovered that elevated indoor air pollutant levels in kindergarten possess a negative impact with respect to learning performance which raises respiratory risk complications. However, there is still a lack of comprehensive information on indoor air in kindergarten worldwide. This study systematically reviews influencing factors of indoor air pollution (IAP) in kindergartens. This paper reviewed articles from Web of Science and Scopus, between year 2000 and 2022 and chose 41 articles. This study adapted the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) method to perform a Systematic Literature Review (SLR). The factors influencing IAP are grouped into three categories such as outdoor source factors, built environment factors, and occupant related factors. The carbon dioxide (CO2) concentrations were greater than 1,000 ppm in classrooms and mainly influenced by ventilation mode, occupant density, and physical activity. Particles (PM10, PM2.5) and carbon monoxide (CO) had the highest concentration levels when there was activity involving cooking besides introduction from outdoors through natural ventilation. In order to optimise the well-being of children, future kindergarten buildings should be designed or retrofitted with a holistic approach. Therefore, the potential of architectural design for children’s spaces in mitigating IAP is a promising initial step.

Walkability is a significant and well-known study to make the built environment to be walkable. However, there is a scarcity of material that aims to investigate the structure and research trends of walkability in recent years. Therefore, the objective of this systematic review is to investigate the structure and research trends in walkability. By applying the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) review method, a systematic literature review (SLR) identifies 50 studies by walkability from 2021 to 2022 from the 3 well-known databases for searching scientific publications including Web of Science, Scopus, and Sage. A mapping technique using VOSviewer to identify thematic focus is employed. Based on these 50 studies, it shows that the existing research on walkability within two years consists of some conceptual aspects that underlying walkability studies including ‘the built environment’, ‘walking’ and physical activity’, which then leads to one or some specific problems on physical or perceived factors which ultimately aim to create a walkable area. Hence, it is significant to do more research on the integration between factors in this field to solve the dependence on motorized transportation for future scholarly work. In addition, the usage of tools could enrich the existing literature on this field. It is also noted that various age perceptions to solve walkability issues need to be considered. The research also emphasizes significant authors, journals, references, countries, and organizations that have contributed to the development of the walkability literature to elaborate in more detail on thematic focus.

Purpose: This study intends to analyze the trend of walkability research over two years (2021–2022) in several aspects, including the research problem, gap and aim underlying walkability issues, research setting, the scale of analysis, the type of data, the data collection tool, the analysis method and contribution.Design/methodology/approach: Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) is employed to conduct a systematic literature review from three leading databases including Web of Science (WoS), Scopus and Sage.Findings: From the review, it can be concluded that the research focuses on two aspects, namely, the built environment and people. The studies in this field are conducted at different scales of the built environment, from macroscale to microscale, including region, city, neighborhood and street-level studies that are conducted around the world including Asia, Europe and America which receive high attention from researchers. Meanwhile, the study of walkability in Australia and Africa gains less attention. It is revealed that there are four factors of walkability including land use and accessibility for macroscale which cover region, city and neighborhood, while street network and pedestrian infrastructure and facility are mainly analyzed for street-level. Most of the studies widely utilize a quantitative approach for analyzing physical walkability factors in a measurement-based approach by using certain tools/software, and a perception-based approach by using questionnaires.Research limitations/implications: The findings can assist to keep up with the rapid pace of scientific publications and help accelerate the understanding of particular ideas in the field of walkability for the planning and design practice and policy that can be used by researchers/academia, urban designers, urban planners, architects, engineers and policymakers. Also, this study hopefully could assist further research direction for the future and could add value to a more advanced way of understanding the research on walkability.Originality/value: This research provides a robust framework for walkability trend analysis and a comprehensive understanding of the main ideas from the existing research on walkability worldwide.

Offshore wind is in a rapid transitional phase, pushed worldwide by efforts of those to reduce climate change. Wind power is becoming a commercialised, unsubsidised competitive form of low carbon generation of renewable energy. Marketplaces reflect this growing trend with the first introduction of subsidy free bids in a tender for the Dutch and German governments. The analysis of surrounding literature of subsidy free bids and governmental policies revealed that integration of subsidy free bids have been carried out to various extents. Bids like those seen in the German and Dutch governments have been done in accompaniment with supportive policies and measures. For the UK, a possible subsidy free bid could be developed under the Scottish Sectoral Marine Plan. Owing to that, this paper investigates the feasibility of a subsidy free bid for the Scottish government. Utilising the Department for Business, Energy and Industrial Strategy (BEIS) levelised cost of electricity (LCOE) metric were inserted into a detailed excel spreadsheet. This paper calculates multiple financial scenarios under the LCOE metric to provide an insight into the possible scenarios of which different models of subsidy free bids can be implemented. The main parameters associated with the BEIS metric and calculator design were investigated. These included financial cost predictions, discount rate, generational capacity and net capacity factors. The final conclusion of the generated output data, showed it was indeed possible to adopt a subsidy free bid under the current UK contract for difference (CfD) scheme under strict and favourable conditions.

The pressure to provide social housing in a fast and economic way, as well as outdated regulations, constrain the design of these buildings, having serious implications for the comfort of occupants and the environment. This becomes more critical in hot-humid climates, such as Malaysia, with uniformly high temperature and humidity and low wind speeds. In its capital, Kuala Lumpur, an extensive program of construction for high-rise social housing is being carried out, however, shortly after the flats are occupied, or as soon as they can afford it, the residents fit wall mounted air conditioning units. This research started by looking at Malay vernacular architecture and the traditional strategies for ventilation and cooling. After a review of current building regulations and green tools employed in the country, two campaigns of fieldwork were carried out to assess the actual indoor and outdoor thermal and air quality conditions in the buildings, which were found to be inadequate for both the local regulations and international recommendations. The fieldwork also allowed the identification of the critical design issues to address. A ventilation and filtering ceiling system has been identified as one of the possible solutions for the current situation and has been tested through physical and computer models. The system improves comfort by reducing the air temperature, humidity, and amount of airborne particles and gases, as well as constantly providing an adequate airflow rate. It is the first attempt to develop what we have named the ‘airhouse’ standard for tropical countries.