Hot Climate Regions Research Articles

Effect of phase change materials on building heating and cooling load considering different wall combinations

In this study, energy analyzes were carried out on a sample building for wall types where 3 main materials (brick, concrete block, aerated concrete) and 3 different insulation materials were used in different combinations, taking into account the situations with and without PCM. Building heating and cooling loads for 39 different scenarios derived in this way were determined by taking into account the coldest and hottest days of the year and also as the total energy need during the year. Analyzes were made with the Design Builder program and the results are presented with tables and graphs. By comparing and classifying the total energy loads of wall samples created for 39 different scenarios during the year, wall types that gave more positive results were determined. Three different PCM types with melting temperatures of 21 °C, 23 °C and 29 °C were used in the analyses. Based on the main material of the wall, three walls with the best performance among their main materials were initially determined. Then, among the wall types consisting of these 3 main materials (brick, concrete block, aerated concrete), the walls that showed the best performance were determined among the combinations created with the addition of insulation material and PCM. The best results with PCM were obtained for XPS as insulation material and aerated concrete as wall type. According to the results of the simulations, 25% energy savings were achieved when only insulation materials (XPS, EPS, Rock Wool) were used in the building envelope, and 9% energy savings were achieved when only PCM was used. By using PCM and insulation materials (XPS, EPS, Rock Wool) together, 30% energy savings were achieved.PCM, which is used in addition to the insulation materials used in the building envelope to reduce the energy load of the building, has led to a decrease in the annual energy need of the building. The combined use of PCM and insulation material can be recommended for regions where the heating load is high. It will be more effective to use PCMs with low melting points in cold climate regions, and PCMs with high melting points to be used in temperate and hot climate regions. It has been advised using PCM with two melting temperatures instead of using PCM with a single melting temperature in the building envelope as a more advantageous solution.

Architecting Ultra-Robust Zr(IV) Metal-Organic Framework for Energy-Efficient Desiccant Air Conditioning.

Air-conditioning systems, composed mainly of humidity control and heat reallocation units, play a pivotal role in upholding superior air quality and human well-being across diverse environments ranging from international space stations and pharmacies to granaries and cultural relic preservation sites, and to commercial and residential buildings. The adoption of sorbent water as the working pair and low-grade renewable or waste heat in adsorption-driven air-conditioning presents a state-of-the-art solution, notably for its energy efficiency and eco-friendliness vis-à-vis conventional electricity-driven vapor compression cycles. Here, we introduce a rational π-extension strategy to engineer an ultrarobust and highly porous zirconium metal-organic framework (Zr-MOF). This MOF sorbent showcases hysteresis-free S-shaped water sorption isotherms, characterized by a rapid ascent within the 40-60% relative humidity range with a working capacity of 0.63 g g-1, thus facilitating intelligent indoor humidity regulation. Moreover, we demonstrate, for the first time, that this material with such distinctive isotherms can yield a 10 °C temperature lift between ambient and chiller output with a high cooling capacity of 336 kW h m-3 per cycle, even at exceptionally low driving temperatures (below 50 °C), while also delivering a substantial coefficient of performance of 0.96. This material is amenable to scale-up and is chemically ultrastable that can endure strong acids and be cycled for at least 200 runs without compromising any of its capacity. These exceptional attributes signify the viability of this material as a pragmatic alternative for deployment in energy-efficient desiccant air-conditioning systems, particularly in hot and humid climatic regions.

An energy saving potential evaluation method of a pipe-embedded wall integrated with natural energies

Pipe-embedded wall (PEWall) can be integrated with various natural energies to significantly reduce building load and energy consumption. However, a general method for quickly assessing the energy-saving potential of such different systems is currently lacking. To address this gap, a novel evaluation method based on revised degree hour is presented. This method focuses on the determination of main parameters essential for accurate assessment. The proposed method is validated by comparing its results with that of a reference model, demonstrating good accuracy. Case study is conducted to evaluate the energy saving potentials of the PEWall with the ground source heat exchanger (GSHE), the cooling tower (CT) and the solar energy collector (SEC) in Wuhan, a hot summer and cold winter climate region. The evaluation results show that, the energy savings of the PEWall-GSHE system for cooling and heating can reach 6.51 kWh/m2 and 2.79 kWh/m2 respectively, demonstrating good energy saving potential. For the PEWall-SEC system, the energy saving for heating is 3.98 kWh/m2 which is acceptable. For the PEWall-CT system, a limited energy saving for cooling of 1.22 kWh/m2 is presented. In conclusion, this evaluation method can effectively assess the energy-saving potentials of the PEWall with different natural energies.

Stress analysis in the buried polyethylene pipes with viscoelastic behavior: a finite element study

In the current study, the stress distribution in the pipe with viscoelastic behavior in presence of different loading conditions has been investigated. In order to connect the polyethylene (PE) gas pipes, the electrofusion sockets are used. Since joints are one of the most sensitive regions of a structure, it is very important to investigate the local stresses created at the joints of PE pipes. To study the stress changes in the buried pipelines and sockets, the numerical simulation of the problem has been carried out in ANSYS software. To validate the obtained numerical findings, the maximum values of the axial and von Mises stresses in the pipe and socket were compared with the values obtained from previous research, and an acceptable overlap was achieved. In this research, the stress distribution in the PE pipes buried in the soil with and without sockets in presence of thermo-mechanical load has been studied, comprehensively. In the finite element modelling, the pipe and socket are made of PE80 and PE100 materials, respectively. The research results showed that the electrofusion sockets are able to be employed to connect PE gas pipes in hot climate regions. Additionally, the outcomes obtained from viscoelastic socket and pipes compared with the isotropic pipe. The findings demonstrated that the maximum von Misses stress in viscoelastic pipe and socket reduces 21% in comparison with linear elastic state.

Comparative investigation of nanomaterial-enhanced asphalt binders in the UAE: a multifaceted study

ABSTRACT This study explores the impact of incorporating six distinct nanomaterials into asphalt binders to determine their effectiveness in resisting permanent deformation, fatigue and thermal cracking. Additionally, the study aimed to establish the Optimum Nano Content (ONC) for each nanomaterial to achieve the best performance against these distresses. The key findings revealed that asphalt binders with 2% Carbon Nanotubes (CNT) or Nano CuO (NCO) demonstrated the best rheological properties, partially in enhancing Elastic Recovery (ER) and rutting resistance, making them ideal for use in hot climate regions. In terms of fatigue performance, all nanomodified asphalt binders, except 2% NAT, exhibited higher fatigue life (Nf) than the control, with the NCO-nanomodified asphalt binder exhibiting the highest Nf, achieving values six to seven times greater than the control. Most nanomaterials showed no noticeable improvement in low-temperature performance, where the best performance was observed for 2% CNT and 6% Nano Iron Trioxide (NIT). For rutting resistance, the ONC for most nanomaterials was approximately 2%, whereas the ONC for fatigue resistance was typically 6%. A proposed ranking system revealed that sixteen of the nanomodified asphalt binders outperformed the control, with the 2% CNT providing the best-balanced performance, while 2% NAT was the least effective.

Model-based improvement of a trans-critical CO2 refrigeration plant

Abstract Refrigeration sector including heat pumps, cryogenics and air conditioning is responsible for a share close 10% of the global greenhouse gas emissions. Therefore, a huge effort of the scientific and industrial community is needed on the development of technologies allowing to reduce the environmental impact of this sector. The use of CO2 as working fluid has great interest in food chain conservation and participates to the problem of the impact produced by the traditional synthetic fluids, recently oriented also to hydrocarbons. Main problem of plants using CO2 as working fluid is the low COP, which reduces even more in moderate or hot climate regions in which low temperature thermal energy is more required. To assess the benefits introduced by plant optimization and innovative technologies, many advanced thermodynamic models are developed in the last years. Anyway, few software platforms are developed for the comprehensive analysis of plant behaviour. To fill this gap, this paper presents the results of a theoretical and experimental research done on an industrial trans-critical CO2 refrigeration plant. The aim was to set up energy saving solutions finalized to mitigate the intrinsic low COP values. A detailed physically consistent model of the unit has been developed following an integrated zero and mono-dimensional thermo-fluid-dynamic approach. The propagative, capacitive, and inertial properties of the components have been considered, so going beyond of the theoretical approaches that are typical in the sector. A wide experimental characterization of the unit has been done with the aim to validate the model and to use it as tool to predict the effect on the COP of the operating variables. The reduction of the compressor absorption and the potentiality of the energy recovery from energy usually wasted have been analysed.

Thermodynamic analysis of a solar powered ejector cooling system

A steady-state model of an ejector cooling system activated by solar heat is presented and applied in response to the increasing demand of cooling in hot-climatic regions. The system comprises three loops connected by heat exchangers. The first loop, or collection sub-system, includes the solar collectors (both cylindrical-parabolic and flat plate collectors are modeled) and the heat transfer fluid (a thermal oil). The second loop also includes an ejector which uses polytropic efficiencies and provides the power necessary to circulate a second low-pressure stream of the refrigerant through the evaporator and an intermediate-pressure condenser. The third loop connects the load to the evaporator using ethylene glycol. In this study, the model is particularly based on the laws of classical and finite size thermodynamics and incorporates experimentally derived relations for the efficiency of the cylindrical-parabolic collectors as well as an ejector model which is based on physical laws rather than on refrigerant specific correlations used in previous studies. The results include a parametric study analysing the effect of the generator superheating and the calorific flow of the heat transfer fluid on the ejector dimensions and the overall system performance. The impact of the solar collector type on the collector surface and the system performance by a fixed incident radiation was investigated. The results illustrate that using parabolic trough collectors, the exergy efficiency of the entire system and the required collector's area are almost constant with the solar radiation intensity. They are approximately 35 % and 35 m2 respectively. It was also shown that further superheating the refrigerant by an additional 10 °C at the generator exit reduces the ejector's total length by 8.1 %, leading to positive economic impacts on raw material acquisition for the solar-powered ejector refrigeration system. Furthermore, doubling the calorific flow reduced the COP by half and increased the ejector length. The economic analysis of the system reveals two key findings: The largest portion of the initial costs is attributed to the solar collector, which is essential for providing the thermal energy required for the system's operation. The main hourly expense of the system is the electricity cost associated with powering the pumps.

Multi-pronged strategies for enhancing building envelopes toward nearly-zero energy in hot climatic regions

Abstract Growing concerns about climate change and rising energy demands necessitate advancements in building energy efficiency. This study investigates the effectiveness of radiative coatings and thermal insulation, both individually and combined, in reducing energy consumption and carbon footprint for buildings in hot and humid climates. This research contributes to a growing body of knowledge by comprehensively evaluating the combined effects of these strategies. A comparative analysis was conducted using data on energy usage and carbon emissions. The research highlights the effectiveness of envelope-enhancing techniques in reducing energy consumption and carbon emissions. The application of radiative coating led to a significant 13.1% decrease in energy usage, totaling 681.95 MWh, and corresponding emissions of 482.14 tons of CO2. Radiative coating offers the most cost-effective solution with an LCOS of $0.045 kWh−1. When integrating thermal insulation with radiative coating, there was a substantial 12.0% reduction in energy consumption, amounting to 690.39 MWh, and emissions of 488.11 tons of CO2. The integrated model provides significant energy savings at a slightly higher LCOS of $0.052 kWh−1, making it a balanced choice between efficiency and cost-effectiveness compared to using thermal insulation alone. Moreover, the study emphasizes that the combination of Glazing Integrated Photovoltaic (GIPV) with radiative coating can lead to the creation of nearly zero-energy buildings, resulting in a significant energy savings of 34.9%. These results underscore the efficacy of these technologies in achieving significant energy savings and environmental benefits. This study demonstrates that radiative coatings significantly reduce energy consumption and carbon footprints. The combined method with thermal insulation reduces energy, suggesting further optimization strategies in hot and humid conditions. The results of this investigation recommend utilizing Glazing Integrated Photovoltaic (GIPV) to achieve nearly zero-energy buildings. Such integrated solutions not only improve energy efficiency but also make a substantial contribution to environmental sustainability in the building sector.

USING PREDICTIVE ANALYTICS TO IMPROVE SURVEILLANCE OF HEAT-RELATED ILLNESS DURING MILITARY TRAINING

Background: Heat-related illnesses are a critical concern for military personnel, especially those unfamiliar with hot climate regions. The Royal Thai Army (RTA) implements a 10-week military training program encompassing four phases: (1) Heat acclimatization training, (2) Combat fundamentals and unarmed combat training, (3) Armed combat training and tactical training, and (4) Field training exercise and evaluations. Objective: This study aimed to conduct a predictive analysis of heat-related illnesses to enhance prevention programs. Methods: The study utilized secondary data from the RTA Medical Department, incorporating variables such as age, occupation, education, underlying diseases, smoking and alcohol consumption, sleep duration, exercise, medication history, body mass index (BMI), weight loss, body temperature, dark urine, heat rash, and environmental humidity. Multiple machine learning algorithms were employed to develop predictive models. Results: The samples comprised 809 male recruits (103,051 encounters) with an average age of 22. Approximately 12% of the recruits had a BMI ≥30 kg/m2, while nearly 70% and 90% reported tobacco use and alcohol consumption in the past 12 months, respectively. Among the recruits, 16% reported substance use within the preceding 30 days. The eXtreme Gradient Boosting (XGB) model achieved 91% accuracy in predicting heat-related illnesses before Phase 2. The top five predictive variables were Lopburi Province (central region), Songkhla Province (southern region), and Bangkok (capital city), sleep duration before joining military training (hours), and age (years). Conclusion: This study, which applied machine learning techniques to predict heat-related illnesses among Thai recruits, can potentially impact the health and training of military personnel. The comparative analysis of various algorithms identified the XGB model as the optimal performer in predicting heat-related illnesses during the combat fundamentals and unarmed combat training phase. However, it is essential to note that further study is needed to enhance the applicability of our predictive model, which includes expanding its use to new cohorts of Thai conscripts, underscoring our research’s ongoing nature.

Drought risk assessment based on hazard, vulnerability, and coping capacity concepts for hot and dry climate regions of Iran

Due to the complex and multi-dimensional nature of droughts, it is not possible to assess drought-induced damage and its consequences for various social, economic, and environmental aspects of societies by relying only on a univariate index such as precipitation-based drought indices. The present study aimed to develop a practical and scientific framework based on hazard, vulnerability (social, economic, and environmental), and coping capacity to generate a drought risk map for the hot and dry climate regions of Iran. Accordingly, the Drought Hazard Index (DHI), Drought Vulnerability Index (DVI), and Drought Coping Capacity Index (DCCI) were derived from “the Standardized Precipitation Evapotranspiration Index (SPEI)”, “16 social, economic and environmental variables” and “three social, economic variables”, respectively. The layers of all variables of the three indices in the GIS were provided, and they were combined in the form of an equation to produce a drought hazard map of central and southeastern Iran. The results indicate that the counties most and least vulnerable to drought were located in the southeast and west of the case study area, respectively. A number of large households, long distances from provincial centers, and soil erosion were the most important social, economic, and environmental factors making the southeast of the case study (including south of Sistan and Baluchestan and south of Kerman provinces) most vulnerable to drought. Due to their high drought coping capacity, counties located in the west of the case study (west of Kerman and south of Yazd provinces) were least vulnerable to drought. Extended support for low-income households by charitable organizations, tertiary education, and most importantly, a variety of jobs and career opportunities were the most important factors in reducing vulnerability in this part of Iran. Furthermore, our methodology by taking social, economic, and environmental dimensions into account as risk, vulnerability, and coping capacity indices can be far more efficient than the methods considering only risk and vulnerability factors.

Endogenous ethanol- and thermo-tolerant strain from Malaysia pineapple peel: Screening and molecular characterisation

The current study aims to identify an endogenous acetic acid bacterial strain isolated from a Malaysian pineapple capable of tolerating high ethanol and temperatures. A total of 23 strains of presumed acetic acid bacteria were isolated from the pineapple peel waste. Subsequently, three isolates with the highest acid yield were subjected to 16S rDNA sequencing; Acetobacter tropicalis (A. tropicalis), Staphylococcus haemolyticus, and Staphylococcus ureilyticus. Tolerance evaluations against pH, temperature, ethanol, sugar, and acetic acid demonstrated that all three strains tolerated significant temperatures, ethanol, and sugar levels. Based on the results, A. tropicalis possesses the potential to reduce cooling system load during acetic acid manufacture in hot climate regions with a notable acetic acid yield.

Reinterpretation of Passive Cooling Strategies in Hot And Dry Climate Traditional Architecture: Vents in The Building

The building sector is among the most critical factors affecting environmental sustainability due to its impacts, such as energy consumption and greenhouse gas production. The reasons for energy consumption and greenhouse gas production in the building sector may vary according to climatic characteristics. In hot and arid climate regions, a significant portion of energy consumption is caused by indoor cooling, especially since the focus is on reducing the indoor temperature. In the periods when traditional architecture was developed, the lack of technological products that would increase energy consumption was effective in providing indoor air conditioning with passive design strategies. This study aims to identify the building openings for natural ventilation and cooling used in the traditional architecture of hot and dry climates and to analyze and evaluate their modern interpretations. A total of 235 award-winning projects were analyzed, and 21 were included in the study. In this context, it was determined that 16 different strategies used in traditional architecture were re-interpretation, and their modern interpretations were analyzed through award-winning projects. The traditional passive design strategies identified in this context have been adapted to modern architecture in 18 types. Wind orientators come to the forefront. In addition, it was determined that the strategies adapted to modern architecture are generally integrated. This study guides modern interpretations of traditional passive design strategies for sustainable building design.

Data analysis and review of the research landscape in performance-enhancing thermal management strategies of photovoltaic technology

New researchers in Performance-Enhancing Thermal Management Strategies (PETS) for photovoltaic (PV) technology struggle with scattered data, hindering their efforts. This research gap is addressed by extracting key information from 1,474 documents in the Web of Science and Scopus databases and conducting a thorough data analysis. The findings reveal three phases of the trend inception, gradual growth period, tech-advanced period, and rapid progress. The bibliometric results show a 24.98% growth rate, 25.01 citations per document, 2,577 researchers involved, and 275 production sources. China, India, and other Asian countries are the main collaborators in this field, emphasizing the impact of hot climate regions in Asia on the choice of PETS methods. The main researchers collaborating with PETS are Sopian. K, Jie Ji, and Pie Gang. Furthermore, a review of keywords suggests that most experimental and numerical studies have prioritized temporal and performance outcomes, often neglecting long-term practical viability considerations. Future research should prioritize the 4E (Energy, Exergy, Economic and Environmental) analysis approach to address this gap effectively. Advancements in evaporative cooling and PVT technology have evolved in offshore solar plants, PV with heat pumps, and building-integrated PV (BIPV). This analysis sets the stage for future PV advancements in PETS technology.

A novel decision support system for designing fixed shading systems in the early design stage: A case study in Egypt

Solar shading is a crucial element that can significantly impact lighting conditions and energy consumption, especially in hot regions. However, selecting the best shading design that achieves optimal daylight performance while meeting architects' requirements is very challenging. This is because it involves considering many design parameters and balancing multiple objectives. The paper introduces a decision support system for designing fixed shading systems to enhance interior environments and reduce energy consumption. Parametric simulation, a meta-model based on automatic selection of regression machine learning algorithms (RMLA), and non-dominated sorting genetic algorithm II (NSGA-II) are used to prepare the designs for selection. Three multiple criteria decision-making (MCDM) methods are employed: the analytic hierarchy process (AHP), entropy, and the technique for order preference by similarity to the ideal solution (TOPSIS) in two combinations (AHP-TOPSIS and entropy-TOPSIS) to adapt to different expert availability scenarios. The proposed method is coded and automated with an easy-to-use interactive interface for flexibility and easy application. The method is applied to help design a fixed shading system for hot climate regions in Cairo, Egypt, which involves considering five objectives: useful day light illuminance (UDI), energy use intensity (EUI), solar gains (SG), daylight autonomy (DA), and continuous daylight autonomy (CDA). The proposed method can provide an efficient design that significantly improves daylight performance. Different dataset sizes are used for training the meta model to study their effect on the final selected design. A sensitivity analysis is done to explore the impact of changes in experts’ opinions on the decision-making process.

Thermal comfort in a two-storey malaysian terrace house: Are passive cooling methods sufficient in present and future climates?

Rising temperatures due to climate change will impact both the indoor thermal comfort of naturally-ventilated housing and the cooling energy needs of air-conditioned housing in tropical regions. This study aims to evaluate the impact of rising temperatures based on the IPCC A2 scenario on indoor thermal comfort and cooling energy in a typical Malaysian terrace house. It addresses three key questions: 1) Can passive cooling (PC) achieve future thermally acceptable conditions? 2) How will PC impact cooling energy with air conditioning (AC)? 3) What is the effectiveness of various PC methods, individually and combined, in controlling indoor climate and saving energy under present and future conditions? We evaluated the effectiveness of eight PC measures—including shading, insulation, solar reflectivity, and nighttime natural ventilation—using EnergyPlus simulations. Results indicate that without PC and AC, indoor temperatures range from 26 to 31 °C, rising to 29–36 °C by the 2050s, often exceeding ASHRAE 55 standards. Currently, combined PC and nighttime ventilation can improve thermal comfort time fraction by up to 87 %. However, by the 2050s, this drops to 38 %, indicating PC alone will be insufficient, and AC systems will be essential. Additionally, in an AC scenario, PC measures reduce cooling energy by 6 % compared to the baseline under future conditions, yet demand is 67 % higher than current conditions. These findings underscore the need for integrating both PC measures and efficient AC systems to mitigate future greenhouse gas emissions from residential sectors in Malaysia and other developing hot climate regions.

A life cycle carbon dioxide equivalent emissions assessment of zero carbon building in hot semi-arid climate region: Case study

As societies are shifting toward carbon neutral environments, they are beginning to account for their carbon emissions. One of the primary contributors of greenhouse gas emissions and global warming is the building industry; therefore, Life Cycle Assessment (LCA) is one of the instruments that allows an assessment of the energy and the energy-related environmental impacts of the buildings from cradle to grave, according to ISO 14040. In this context, the aim of this research study is to assess the Life Cycle carbon dioxide (LC CO2eq) emissions over a 50-year-lifespan of a zero-carbon solar-powered earth-based building, built with carbon-free adobe bricks, in the hot semi-arid climate of Morocco. While research on the carbon dioxide equivalent (CO2eq) emissions across the life cycle is crucial to determine the energy-intensive stages, this study looks into global tendencies of CO2eq emissions arising during the cradle-to-gate embodied (A1-3) and operational (B6) phases of a Zero Carbon Building (ZCB) case study, and which should be offset by carbon-free energy in order to abide by the ZCB definition. Results show that the LC CO2eq emissions of the eco-friendly zero-carbon residential building falls in 48.62 Kg CO2eq/m2.y., with an operational phase that has a share of around 93 % of global LC CO2eq emissions. In addition, when conventional construction materials such as concrete, bricks, and insulation materials are used as an alternative, embodied carbon emissions accounts for 6.3 kg CO2eq/m2.y. and is 85 % higher than the eco-friendly building, and it constitutes approximately 12.5 % of the overall carbon footprint. Moreover, the annual embodied and operational CO2eq emissions are offset by the 3.3-kWc-building-added-photovoltaic system. Hence, the conducted case study offers valuable insight into the good practices for decarbonization of Morocco's building stock.Through that case study, we aim to generate knowledge of net zero carbon buildings within the African continent, promoting the perks of decentralized solar energy in leaping forward a carbon-free electrified continent and valorizing the local construction techniques and knowhow in the building sector.

Optimal design of multilayer optical thin film structure for smart energy saving applications using needle optimization approach

In this work, a novel design of a one dimensional photonic crystal (1D PC) is investigated. The 1DPC structure is composed of alternating layers of tantalum pentoxide (Ta2O5) and silicon dioxide (Sio2). The proposed 1D PC structure is designed to act as short wave pass (SWP) edge filter that selectively passes light of short wavelengths, while the infrared light is blocked. In this study, Essential Macleod software is used to create the optimal design with the computational support of the needle synthesis technique. By varying the incidence angle of the mean polarized light mode, we can determine the features of the optimal SWP edge filter design, which leads to an important application for this filter. It can shed light on the filter’s suitability as a smart energy saving window coating for hot climate regions. The study includes different hot regions in Saudi Arabia such as Mecca, Riyadh, Dammam, Arar and Alaqiq. They were used as case studies in this research. According to the study of the optimal design of SWP edge filter applied in Mecca, Riyadh, Dammam, Arar and Alaqiq provinces, the light transmittance in the visible region is more than 99% during the summer solstice and more than 96% during the winter solstice. The photonic band gab (PBG) is almost constant during the summer solstice without shifting or decreasing in size whereas in the winter solstice, the PBG shifts toward the short wavelengths and decreases in size by increasing the angle of incidence. This allows an amount of solar energy to enter in winter. Riyadh, Dammam, and Arar provinces experienced a significant increase in solar energy during the winter solstice, more than Mecca and Alaqiq provinces.

Subjective evaluation of thermal comfort of tropically acclimatized subjects in air conditioned, naturally ventilated and radiant cooling environments

The thermal sensation of people is subjective. It depends on the external climatic condition and thermal history of a person. Thermal comfort standards suggest a narrow temperature range to assert an environment as comfortable or otherwise. It is important to evaluate people’s thermal perception in different climatic regions and set comfort limits based on their thermal perception. This study evaluates the thermal perception of subjects in hot and humid climatic regions at higher indoor temperatures and air velocities. Three different thermal environments chosen for the study are air conditioned (AC), naturally ventilated (NV), and radiant cooling (RC) thermal environments. The study shows that more than 80% of subjects voted as comfortable in AC and RC thermal environments for the measured Top and va range of 25.3 – 28.4℃/0.1 – 0.3m/s and 25.9 – 29.1℃/0.1 – 0.9m/s respectively. The findings gathered from the study in NV environment indicate that 68% of subjects opt for the use of table fans over ceiling fans. The subjects' free control of air movement improves their thermal sensation over no control of air movement, indicating that they prefer table fans and free control of air movement. In AC, NV, and RC thermal environments, humidity and air quality remain uncontrolled. In AC and RC thermal environments, less than 20% of subjects voted unacceptable for the humidity sensation and Perceived air quality (PAQ) scales in nearly all the studied experimental conditions. In NV thermal environment, the percentage of subjects voting dissatisfied on the humidity sensation scale and PAQ scale is 30-52% and 26-37%, respectively. This outcome shows that a thermally comfortable environment with air movement improves subjects' humidity sensation and PAQ even when humidity and air quality are unaltered. The study points out that air velocity played a vital role in influencing the thermal sensation, humidity sensation and perceived air quality of subjects in the three studied thermal environments. Further the study shows that with free control of air movement will significantly aid in rising the comfort temperature band of tropically acclimatized subjects. Practical application The study shows the variation in limits of thermal comfort indices such as operative temperature and air velocity for tropically acclimatized subjects in three thermal environments. The same group of subjects participated in the subject study conducted in air conditioned, naturally ventilated and radiant cooling thermal environments. The outcomes indicate that subjects are comfortable at higher indoor temperature and air velocity. Further the outcomes showed that the humidity and air quality sensation of subjects is influenced by the subjects’ thermal sensation and air velocity.

Reuse of waste rockwool for improving the performance of LC3-based mortars made with natural and recycled aggregates for sustainable building solutions

The objective of this study is to investigate the effect of waste rockwool (RW) addition on the thermo-physical, mechanical, and fire resistance properties of limestone calcined clay cement (LC3)-based mortars. LC3 binder has been produced by replacing 60 wt% of OPC with limestone (LS) powder and metakaolin (MK) at a percentage of LS to MK of 1:2 (wt%). Waste RW was added at various ratios of 1, 3 and 5 % (by weight of binder) into two types of LC3-based mortars made with natural sand (NS) and ferrochrome waste slag (FCS) aggregates with a binder-to-aggregate vol% of 1:3. Upon the addition of 5 wt% of waste RW, significant enhancements of about 19 % and 21 % were obtained for the compressive strength of NS and FCS mortars, respectively, and attributed to the improved physical packing. After exposure to standard fire for 1 h with a maximum applied temperature of 945 °C, residual strengths of about 57.5 % and 63.8 % have been maintained by the sand and FCS-blended LC3 mortars, respectively. Generally, the incorporation of RW led to a slight increase in the thermal conductivity of both types of mortars; however, the FCS-blended LC3 mortar possessed relatively higher increment rates as compared with the sand mortar, which is helpful in improving the thermal performance in hot climate regions. Remarkable improvements in the microstructure characteristics in terms of compactness, uniformity, and interfacial transition zone (ITZ) tightness were attained by RW addition. Lifecycle assessment (LCA) results demonstrated that about 38–45 % lower carbon emission is associated with the designed LC3-based mortars than the conventional OPC mortar.

Biomimetic Facade Design Proposal to Improving Thermal Comfort in Hot Climate Region

Biomimetic Facade Design Proposal to Improving Thermal Comfort in Hot Climate Region