Hot Climate Regions Research Articles

“The contribution of double skin roof coupled with thermo reflective paint to improve thermal and energy performance for the ‘Mozabit’ houses: Case of Beni Isguen’s Ksar in southern Algeria”

In traditional cities of hot and arid climate regions, roofs are usually the surfaces most exposed to intense sunlight in summer. This leads to high temperatures inside the houses and forces the inhabitants to escape to the terraces at night. On the other hand, some residents use air conditioning and therefore increase energy consumption. This work aims to study the contribution of a double skin roof coupled with a thermo-reflective paint on the reduction of indoor temperature and energy consumption in house located in the Ksar of Beni Isguen in southern Algeria. Firstly, the problem of overheating was identified through temperature and humidity measurements for traditional dwelling in hot season. Secondly, a model of double skin roof coupled with thermo-reflective paint was developed and numerically simulated using TRNSYS software. The obtained results showed that in summer, the temperatures in traditional houses are high compared to the comfort zone. The average indoor operating temperatures exceeded 37 °C during different hours of the day, over the investigation period of three representative days of hot season. Nevertheless, the proposed model reduces the indoor operative temperature by 5 °C. Also, the model was validated against in situ measurements, whose results showed a consistency between the measured and simulated temperature values. In addition, thermal simulation results performed over a period of one year indicate that the overall energy consumption required for cooling loads is reduced by 572 kWh i.e. 66% when optimizing the roof thermal performance.

UROCHLOA GRASS GROWTH AS A FUNCTION OF NITROGEN AND PHOSPHORUS FERTILIZATION

The urochloa grass (Urochloa mosambicensis) is a perennial grass, C4 plant, with a high photosynthetic rate and CO2 fixation, persistent to water deficit, adapted to a wide diversity of soils and hot climate regions. Thus, the objective was to evaluate the urochloa grass growth and define the best models to estimate plant height as a function of nitrogen and phosphate fertilization. The experimental design was completely randomized, in the 2 x 2 factorial design (presence and absence of nitrogen presence and absence of phosphorus), with four replications. Was used a dose of nitrogen and phosphorus equivalent to 100 kg.ha-1 of N and 150 kg.ha-1 of P2O5, respectively. The following models were used: linear, power, gamma andlogistic to estimate plant height as a function of the following explanatory variables: days after planting, nitrogen and phosphorus doses. The criteria used to determine the best model(s) were as follows: higher adjusted coefficient of determination, lower Akaike information criterion, lower sum of square of residuals and high Willmott index. The plant height in the absence of nitrogen and phosphorus and when applied 100 kg.ha-1 of N and 150 kg.ha-1 of P2O5 was estimated more accurately by the Gamma model with high power of explanation. The adoption of the Gamma model allows to estimate the U. mosambicensis plant height, in a non-destructive manner, with high precision, speed and low cost, depending of age plant and nitrogen and phosphate fertilization.

Modelling labour productivity of reinforcement bar using polynomial regression: a study on a tropical country's weather

For many years, the issue of environmental influence on labour productivity has received considerable attention. One of the most significant contemporary discussions in economics and construction management disciplines is about determining how weather factors influence labour productivity. While extant literature is replete with formulas and models applicable to the cold and hot climatic regions, there appears to be a paucity of useful models within the context of tropical countries such as Malaysia. With the increasing concern for climate changes and global warming, predicting how tropical weather factors may impact labour productivity is becoming an important research topic. This study developed a new model using polynomial regression based on actual data collected from a residential project in Kuala Lumpur, Malaysia. The study examined how rebar work is influenced by five weather factors: temperature, relative humidity, solar radiation, wind speed, and rainfall. The results show a 43% productivity variance due to weather factors. Further, the developed model shows how the interaction between weather factors can change the variability of productivity. The proposed model is useful for providing more accurate productivity predictions for construction management. This is useful to project planning and resolving disputes regarding progress claims.

Evaluating heating, ventilation, and air-conditioning systems toward minimizing the airborne transmission risk of Mucormycosis and COVID-19 infections in built environment

This ongoing global pandemic of the COVID-19 has generated a significant international concern for our respiratory health. For instance, the breakout of the COVID-19 pandemic was directly linked to the spread of infectious particles in indoor environments between humans, underlining the significance of rigorous and effective actions to limit the transmission of diseases. Recently, Mucormycosis infections in COVID-19 patients have been identified. This investigation aims to investigate potential infection control HVAC solutions for indoor environments, as well as their core mechanisms for reducing infectious disease risk through simulation models of a valid building in a hot climatic region. Considering recent international recommendations, the investigation relies on a methodology of testing a validated building energy model to several systems in the light of infectious diseases prevention. All proposed models are exposed to cost analysis in line with carbon emissions, and indoor thermal conditions. The analysis outlined through parametric simulations, the effectiveness of the proposed DOAS in supplying 100% fresh ventilation air and enhancing the control of the indoor relative humidity simultaneously. Finally, through an enviro-economic assessment, the study concluded that the DOAS model reduced the CO2 emissions to 691 tons, with a potential of reducing HVAC and whole-building energy use by 37% and 16%, respectively in the hot arid climate, with a return on investment of about 6%.

Estimating the potential of desalinate seawater using solar glass pyramid (SGP) in hot arid zones

Recently, the world starts to suffer from the shortage of fresh water, in which it effect the survivor of people in many countries which cannot afford the costs of desalinate seawater. More than 50,000 children die every year from the shortage of fresh water. In Egypt, the need for fresh water is increasing daily due to the high demands from the growing population. Moreover, Ethiopian dam put Egypt and Sudan in a very risky situation. Egyptian North coast urban settlements are located far away from the River Nile and regular methods for seawater desalination is highly expensive as well as transferring fresh water from River Nile to north coast urban settlements is not an option. This research intends to present cheap system for seawater desalination by integrating solar glass pyramid tank with building sanitation system and replacing it with the regular building water tanks. The presented research used experimental method to investigate the efficiency of solar glass pyramid tank. The research built solar glass pyramid tank in hot arid climate region which is Cairo-Egypt, and measure the amount of seawater desalinated and compare it with the amount of water consumed in single residential house. This tank will desalinate the seawater using the solar radiation to evaporate the seawater and turn it to steam, the steam will be stored in another tank as fresh water. According to the presented research, SGP will satisfy almost 3% of the basic needs for fresh water in single-family unit in which it can satisfy the drink and cooking activity in middle class single family home. The percentage of desalinated water will increase if SGP tank were linked to heater system that accelerate the evaporation process. • Conducting experimental study on desalinate seawater using Solar glass pyramid. • Presenting the design and properties of cheap Solar glass pyramid tank. • Calculating the amount of water produced from the suggested system. • Compare this system with the average water consumed in middle class family.

Framework for Developing a Low-Carbon Energy Demand in Residential Buildings Using Community-Government Partnership: An Application in Saudi Arabia

Rapid population growth has led to significant demand for residential buildings around the world. Consequently, there is a growing energy demand associated with increased greenhouse gas (GHG) emissions. The residential building energy demand in arid countries such as Saudi Arabia is supplied with fossil fuel. The existing consumption pattern of fossil fuels in Saudi Arabia is less sustainable due to the depletion of fossil fuel resources and resulting environmental impacts. Buildings built in hot and arid climatic conditions demand high energy for creating habitable indoor environments. Enormous energy is required to maintain a cool temperature in hot regions. Moreover, climate change may have different impacts on hot climatic regions and affect building energy use differently. This means that different building interventions may be required to improve the performance of building energy performance in these geographical regions, thereby reducing the emissions of GHGs. In this study, this framework has been applied to Saudi Arabia, a hot and arid country. This research proposes a community–government partnership framework for developing low-carbon energy in residential buildings. This study focuses on both the operational energy demand and a cost-benefit analysis of energy use in the selected geographical regions for the next 30 years (i.e., 2050). The proposed framework primarily consists of four stages: (1) data collection on energy use (2020 to 2050); (2) setting a GHG emissions reduction target; (3) a building intervention approach by the community by considering cost, energy, and GHG emissions using the Technique for Order of Performance by Similarity to the Ideal Solution (TOPSIS) to select the best combinations in each geographical region conducting 180 simulations; and (4) a clean energy approach by the government using grey relational analysis (GRA) to select the best clean energy system on the grid. The clean energy approach selected six different renewable power generation systems (i.e., PV array, wind turbine, hybrid system) with two storage systems (i.e., battery bank and a combination of electrolyte, fuel cell, and hydrogen tank storage). This approach is designed to identify the best clean energy systems in five geographical regions with thirty scenario analyses to define renewable energy-economy benefits. This framework informs through many engineering tools such as residential building energy analysis, renewable energy analysis, multi-criteria decision analysis (MCDA) techniques, and cost-benefit analysis. Integration between these engineering tools with the set of energy policies and public initiatives is designed to achieve further directives in the effort to reach greater efficiency while downsizing residential energy demands. The results of this paper propose that a certain level of cooperation is required between the community and the government in terms of financial investments and the best combinations of retrofits and clean energy measures. Thus, retrofits and clean energy measures can help save carbon emissions (enhancing the energy performance of buildings) and decrease associated GHG emissions, which can help policy makers to achieve low-carbon emission communities.

Light and thermal management of the semi-transparent radiative cooling glass for buildings

Transparent envelopes account for a large amount of energy consumption of buildings, especially in hot climate regions. Glass is one of the main materials in transparent envelopes, so modifying the radiative properties of the glass is an alternative way for building energy saving. Here, a semi-transparent radiative cooling (ST/RC) glass was proposed by integrating the selective utilization of solar energy and passive radiative cooling. Comparative experiments based on two small-scale boxes were performed, which shows that the indoor air temperature of the box with the ST/RC glass is lower than that with the ordinary glass and the maximum temperature difference reached 16.4 °C, indicating that ST/RC glass can reduce the waste heat generated in the indoor environment. Besides, the daylighting level with the ST/RC glass is decreased by approximately 2/3 to support comfortable daylighting. Moreover, large-scale modeling of the building located in the Maldives was conducted and results show that the energy consumption of building could be saved by 21%–66.5% when the glass is modified to transmit visible light, reflect other solar irradiance, and emit like a blackbody, which indicates that the strategy of using light and thermal management of glass has the potential to reduce the energy consumption of buildings.

Performance evaluation of independent global solar radiation estimation models for different climatic zones: A case study

ABSTRACT Rapid technological advancement in solar applications requires accurately determined daily global solar radiation (DGSR). The independent models to predict DGSR are super cited as they do not require any other climatological or geographical parameter. In this study, nine day-of-the-year based (DYB) independent models are developed to estimate daily global solar radiation in Pakistan. The meteorological data from the year 2000–2017 is used while covering thirty locations from five climatic zones of Pakistan. The models’ performance is statistically assessed in terms of normalized mean bias error (nMBE) and normalized root mean square error (nRMSE). The results indicate that the two Gaussian function model estimates DGSR with a satisfactory performance at most stations in different climatic zones. On average, the correlation coefficient and index of agreement between day-of-the-year and DGSR are 0.934 and 0.956, respectively. The two Gaussian function model is then further compared with four existing best claimed models found in literature. Results show that the nMBE and nRMSE ranges from 0.87 to 3.00 and 0.95 to 3.21, respectively. Thus, it shows that the existing models overestimate the DGSR and are not applicable for long-term planning. In comparison, for the present study, nMBE and nRMSE take values between −0.05 to 0.17 and 0.09 to 0.24, respectively. Furthermore, Global Performance Indicator (GPI) is used to rank the models based upon their prediction performance which ranges between −3.5626 and 4.1998. The study revealed that DYB models are best suited for hot climatic regions of Pakistan as compared to cold climatic zones. Also, the locations within the China Pakistan Economic Corridor (CPEC) highway network have maximum accuracy. This study can help energy system designers to predict DGSR values at any location in Pakistan.

Energy model calibration in an office building by an optimization-based method

In the last years, building energy consumption minimization has come to be an important issue for designers also architects. Different building energy simulation (BES) tools were applied. These programs are efficient to estimate building energy demands and quicken the malfunction assessment. Many of the provided energy simulation tools cannot precisely forecast building energy operation because of numerous interacting variables. To lessen considerable discrepancies between the actual-time data measurements and the simulation achievements, an optimization-based calibration method is presented in this study. Therefore, to minimize this error an optimization algorithm called Slime Mold Optimization (SMO) algorithm is utilized also the energy simulation model. A case study, an office building placed in Dubai, the United Arab Emirates (UAE) in a humid and hot climate region is selected to be modeled and adjusted to show the accuracy of the applied procedure. This case has five floors with 3610 m2 footprint. The building uses only electrical power as the major energy source For the total dataset duration (n = 3216), the MBE of an hour for the calibrated model is equal to 3.24 percent with the CV (RMSE) equal to 11.3 percent. The statistical evaluation has been used for analyzing the precision of the achievements. Based on the results, the procedure is reliable.

Loading PCM Into Buildings Envelope to Decrease Heat Gain-Performing Transient Thermal Analysis on Nanofluid Filled Solar System

The high share of buildings in energy consumption and carbon dioxide emission has led researchers to seek techniques to reduce energy consumption in this sector. In this study, considering a hot and arid climate region, the wall’s heat gain was investigated. To reduce energy demand, three techniques of adding PCM, combining absorption chiller with a solar system and dispersing nanoparticles were used and the results were evaluated transiently. In July, the addition of PCM to the building's walls reduced the heat exchange between interior and exterior spaces up to 21%. To cool the interior spaces, the combination of absorption chiller + fan coil was used and several flat plate collectors were integrated with it to reduce energy demand. By collecting energy in solar collectors and using a stratified tank, energy consumption in the generator section was reduced by 450 kWh. Nanoparticles were used to improve the solar system performance and it was found that loading ZnO and Al2O3 nanoparticles is useful. Dispersing ZnO into water increased the energy-saving by 9.5% while the second nanoparticle improved it by 14.5%.

Slag-based geopolymer concrete incorporating ash: effects on thermal performance

ABSTRACT The thermal performance (TP) of concrete structures is vital to the evaluation of the fire response. Thus, this study examined the thermal properties slag-based geopolymer concrete (GPC) incorporating corncob ash (CCA). Corncob was valorised and partially used as a substitution for slag under the ambient curing conditions. Sodium hydroxide (SH) solution and sodium silicate (SS) gel were used as alkaline activators at 12, 14, and 16 M concentrations. The TP of GPC was compared with that of Portland cement concrete (PCC). Thermal predictions were developed based on the thermal properties. Based on the findings, GPC exhibited lower thermal conductivity (TC) and thermal diffusivity (TD) with increasing specific heat capacity (SHC), indicating good thermal insulation properties (TIP) compared with PCC. The TIP increased with increasing CCA content in the mixture at all levels of alkaline activators. Thus, CCA improves the insulating capacity of the GPC. In addition, a good correlation exists between the GPC produced and thermal properties. These findings can be beneficial in the hot climate regions and utilised for structural insulating construction concrete. Finally, the proposed models can be used in the assessment of GPC structures incorporating supplementary cementitious materials (SCMs) to enhance the TIP of construction materials.

Effect of part deformation on performance of a rotary compressor using propane under high temperature

• A complete research chain from part deformation to performance was achieved. • Thermal load had greater influence on deformation comparing with force load. • The subsidence of the main bearing is the most severe deformation. • Part deformation changed leakage distribution and reduced its total amount. • With deformation correction, the relative errors of performance simulation are reduced. The residential air conditioners using propane have advantages in hot climate regions due to its low discharge temperature and high performance. However, there is greater part deformation because of larger pressure difference and higher ambient temperature. The part deformation of rotary compressor has not been investigated completely about its main factor and the effect on performance. This paper simulated the temperature distribution and part deformation with finite element method, and proposed a calculation method of clearance variation based on the simulation results for performance research. The results indicated that thermal load has about ten times influence of the force load on deformation. The subsidence of the main bearing end face is the most severe deformation whose maximum value is 10 μm, and leads to a maximum reduction of 38% in related clearance. The leakage distribution is completely changed by part deformation, and the total amount is reduced by 14%. The correction of part deformation improves the accuracy of the performance simulation software, whose relative errors of volumetric efficiency and coefficient of performance (COP) reduce by 0.6% and 1.1% at most.

An adaptive thermal comfort model for naturally ventilated classrooms of technical institutions in Madurai

PurposeOccupants dwelling in hot climatic regions of India for a longer term are tolerable to high temperature levels than predicted by American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) standards. The purpose of this study is to evaluate the thermal sensations (TS) and neutral temperature of the occupants in naturally ventilated (NV) and air-conditioned (AC) classrooms of two technical institutions located in the same premises in the suburbs of Madurai. The main focus of this study is to understand the occupants’ behaviour in response to the thermal conditions of the educational buildings particularly in the warm and humid climatic zone of Madurai.Design/methodology/approachThis research collected data through field studies. The data included 383 survey questionnaires from NV classrooms and 285 from AC classrooms, as well as on-site measurements of interior and exterior weather conditions. The TS results show that the students preferred well-designed NV classrooms than AC classrooms. A new adaptive comfort equation derived from this study can be applied to NV classrooms in warm and humid climates where mean outdoor temperature exceeds 40°C.FindingsThe neutral temperature derived for NV classrooms in Madurai ranged from 29°C to 34°C. Thus, the occupants in the NV classrooms of the higher learning educational institutions in the warm and humid climatic region of Madurai can adapt well to higher indoor temperature levels than predicted by ASHRAE comfort levels with minimum adjustments.Research limitations/implicationsThe study was limited to only occupants in two premier higher learning technical educational institutions located in Madurai region within 5–10 km within the city limits to understand the implications of microclimate with respect to the urban context. Thus, further research is required to examine the tendency under local conditions in other regions beyond those applied to this study.Social implicationsThe findings of this study showed that occupants in higher learning educational intuitions in Madurai prefer NV classrooms than AC classrooms. Therefore, with rising demands of energy use for mechanical ventilation and the associated high cost for running AC buildings, architects should prioritize the design of energy efficient buildings through the optimal use of passive design strategies for ventilation and thermal comfort. This study gives a base data for architects to understand the adaptive limitations of occupants and design NV buildings that can promote natural ventilation and provide better thermal environments that can help increase the productivity of students.Originality/valueThis paper was an attempt to develop the adaptive comfort model for NV classrooms in Madurai regions. There has been no attempt to identify the adaptive comfort levels of occupants in higher learning technical educational institutions located in warm and humid climatic region of India.

Experimental investigation of a passive cooling system for photovoltaic modules efficiency improvement in hot and arid regions

Photovoltaic systems convert only a small amount of incident solar insolation into electrical energy while the rest is dissipated into heat. The increase in the PV cell temperature decreases significantly the electrical efficiency by about 0.5% for each 1 °C rise. Hence, it is necessary to keep the module temperature at low values to improve the efficiency and to minimize the thermal degradation effect. In this research paper, a passive cooling system was developed to mitigate the overheating of PV modules in order to enhance their performance. The developed cooling system is based on water evaporation and the capillary action of the burlap cloth that was attached directly to the rear surface of the module. Thermal and electrical characteristics of the modules (with and without cooling) were investigated experimentally under outdoor conditions during summer days of a hot climate region. Experimental results showed that a PV module temperature reduction of 20 °C (26%) was achieved with the help of the developed evaporative cooling system leading to an important increase of 14.75% in the electrical efficiency. The results also revealed the high effectiveness of the developed cooling system in the reduction and the maintaining of a uniform temperature distribution over the PV module throughout the day. Furthermore, this cooling system has many advantages such as being environment-friendly, low investment cost and low water consumption 0.39 L/h.

Soil yeast abundance and diversity assessment in a hot climatic region, semi-arid ecosystem.

Background and Objectives:Yeasts are an important portion of microbial communities of soil due to their bioactivity for ecosystem safety. Soil yeast abundance and diversity are likely to be affected under harsh environmental and climatic conditions. In Iraq, human activity and climatic changes especially high temperature which may alter microbial communities in soil. Very little is known about yeast abundance and diversity in a hot climatic region.Materials and Methods:By PCR technique, soil yeast abundance and diversity were investigated under extreme environmental and climatic conditions, as well as the effects of soil properties and vegetation cover in semi-arid lands.Results:In all, 126 yeast strains were isolated and identified as belonging to 13 genera and 26 known species. The maximum quantity of yeast was 0.8 × 102 CFU g−1 of soil, with significantly varied in abundance and diversity depending on soil properties and presence of vegetation.Conclusion:The results show that soil yeast abundance in these regions was significantly decreased. However, semi-arid lands are still rich in yeast diversity, and many species have adapted to survive in such conditions.

Determining the optimum fixed solar-shading device for minimizing the energy consumption of a side-lit office building in a hot climate

Buildings consume nearly 40% of the annual global energy consumption, with about 70% in hot climate regions. An efficient building design in every aspect is a crucial step towards minimizing such consumption. Windows system, including solar shading attachment, plays a pivotal role in designing a sustainable building. At the beginning, a survey of architectural firms was conducted to assess the current local practice of selecting the type and size of solar shading devices in different orientations. Regrettably, the survey outcomes did not consolidate the designers’ basis for choosing such solar shading devices. Therefore, the main aim of this study is to find the optimum solar shading type and size among the three most common types (simple overhang, louvers, and overhang/sided-fins) in each façade orientation (East, West, North, and South). The manipulated design parameters comprised the overhang projection from the wall base to half of the window’s height and sided-fins projection (from the wall base to half of the window’s width), as well as the overhang projection’s tilt angle (from 90° to 135°). The considered design parameters provide 4416 design options that were handled efficiently by using the simulation-based optimization technique (SBOT). The results showed that the overhang/sided-fins performed best in terms of reducing the total energy consumption in all orientations (13-28%), while louvers’ shading came second on all orientations by saving 10–21% except in the East, where the simple overhang showed slightly better performance by saving 22%. Recommended type and size for the solar shading in each orientation have been provided.

Changes in anti-nutrient, phytochemical, and micronutrient contents of different processed rubber (Hevea brasiliensis) seed meals.

Rubber (Hevea brasiliensis) is a perennial plant crop grown in many parts of Africa, South East Asia, and South America, especially within the hot and humid climatic regions. Rubber seed, either as feed or food, is a useful raw material to produce edible oil and protein. Despite the huge quantity of rubber seeds produced in Nigeria and its potential as a protein source, rubber seeds still appear neglected and under-utilised as feed/food given its perception as inedible and toxic due to the high concentration of cyanogenic glycoside. Therefore, the quest for effective processing technique(s) that would enhance its food use application is very fitting. This current study was directed to determine the changes in anti-nutrient, phytochemical, and micronutrient contents of different processed rubber seed meals. Specifically, the rubber seeds underwent processing, which employed boiling and the combined action of boiling and fermentation methods that brought about three seed meal flour groups, i.e., raw (RRSM), boiled (BRSM), and fermented (FRSM) seed meals. These were subsequently analysed for anti-nutrient/phytochemical (oxalate, phytate, tannin, phenols, saponin, hydrogen cyanide (HCN), alkaloids, flavonoids, and trypsin inhibitors), and micronutrient (which involved minerals (magnesium, phosphorus, calcium, iron, zinc, potassium, sodium, manganese, lead, and selenium) and vitamin (vitamin B1, B2, B3, C, E, and beta carotene)) contents. The results showed that the processing methods used to achieve the RRSM, BRSM, and FRSM, reduced the anti-nutrients (phytate, tannin, and oxalate) below the acceptable limits, and the HCN below the toxic levels. Importantly, the processing methods herein have not yet succeeded in removing HCN in the (processed) rubber seed meals, but can be seen to be heading toward the right direction. The FRSM obtained significantly lower (p < 0.05) anti-nutrient/phytochemical, but significantly higher (p < 0.05) mineral contents, compared with the other groups (RRSM and BRSM), except for flavonoids that obtained a 30% increase over the BRSM. Some mineral and vitamin contents could be lost in the BRSM compared to the others (RRSM and FRSM) in this study. Additionally, the FRSM obtained higher vitamin contents, after those of RRSM. Overall, the combined action of boiling and fermentation should be recommended for the proper utilisation of rubber seed as food/feed.

An integrated system of water-cooled VRF and indirect evaporative chiller and its energy saving potential

• An indirect evaporative cooling variable refrigerant flow system was proposed. • A mathematical model of the proposed system was developed. • The energy performance of the proposed system was evaluated. • A very high seasonal energy efficiency ratio of 7.48 was found. • It is suitable to be used in hot and semiarid climate regions. Evaporative cooling is an energy efficient and environmentally friendly cooling technology and has been widely used for indoor air conditioning in hot and arid climate regions. In order to apply evaporative cooling technology to hot and semiarid climate regions, an integrated system, which combined indirect evaporative cooling and variable refrigerant flow (VRF) technologies, was proposed. In the proposed system, cold water produced by indirect evaporative chiller (IECh) is firstly used to cool the fresh air and then used as cooling water for a water-cooled VRF system. To investigate the feasibility and its energy saving potential of the proposed system in hot and semiarid climate regions, a mathematical model was developed and a simulation program was developed. The energy performance of the system during the cooling season is evaluated in a typical office building in Turpan of China. Results show that the proposed system has a seasonal energy efficiency ratio (SEER) of 7.48. Compared with conventional air-cooled VRF system, the proposed system can help to reduce energy consumption by approximately 35%. Therefore, it is feasible to apply the proposed system for indoor climate control in hot and semiarid climate regions with remarkable energy savings.

The effects of shading devices on office building energy performance in Mediterranean climate regions

Fixed shading devices (SDs) are still used as an essential and useful element in architectural design. Even with minor changes to be made when designing these devices, the energy performance of a building, especially in hot climate regions, can be significantly increased. In contrast to studies using one or a few parameters, this study aimed to make a comprehensive evaluation by considering more parameters simultaneously to determine energy-efficient fixed external SD scenarios that can be used in office buildings. This approach increases the accuracy of the results in terms of providing trade-offs. This study also aims to fill the gap of the research on SD strategies in Turkey. A total of 1485 scenarios were created with fixed external SDs (overhangs, horizontal and vertical louvers, and egg-crate variations) using the parameters of direction, glazing type, window-to-wall ratio (WWR), SD depth, and slope. Primary energy consumption values of all scenarios were calculated with the DesignBuilder software. Results were discussed according to the impact of each parameter on energy consumption and evaluated through descriptive statistical analysis. As a result, energy-efficient scenarios were determined. The best scenarios obtained for each SD type reduced the cooling energy consumption by between 37% and 49% compared to the no shading scenario using high-performance glazing type and by between 73% and 78% compared to the no shading scenario using low-performance glazing type. The total annual energy consumption was reduced by approximately 33% and 70%, respectively.

A novel thermal regulation method for photovoltaic panels using porous metals filled with phase change material and nanoparticle additives

The main problem with different types of PV cells is that they heat up beyond their optimal working temperature and thereby reduce their power generation efficiency. PV panel's thermal regulation utilising phase change material (PCM) has been a popular choice to counter the problem; however, the low thermal conductivity of PCMs is still an open challenge to fully exploit these materials as a potential solution. The effects of dispersing nanoparticles within the combination of PCM and copper foam matrix (CFM) on the PV panel performance was studied experimentally, under the climatic condition of Baghdad's city centre as a case study of a hot climate region. The results demonstrate the effect of the bundles of tangled tubes of the multi-walled carbon nanotubes (MWCNTs) additives with a 0.2% concentration ratio within the PCM/CFM, greatly improved the effective thermal properties of the material through the absorption and the rejection of heat. As a result, the electrical performance of the cells improves, which lead to an increase in the average electrical efficiency of the PV panel from 4% to 21% on the test day, when compared to the PV panels without passive cooling materials.