Hot Dry Climate Research Articles

The effect of climate-responsive design on thermal and energy performance: A simulation based study in the hot-dry Algerian South region

The building sector in Algeria was influenced by French colonisation in terms of typology and materials (in particular, housing sector was the most influenced), but the local traditional architecture is full of forms of harsh climate resistance. The severe hot-dry climate regions are the most affected, due to the high temperature degrees which made the government reducing electricity and gas bills tariff by 65%. The purpose of this paper is to explore the role of passive strategies inspired from traditional architecture in hot-dry climate in affecting the energy demand (cooling and heating loads). A typical case study of El-Miniawy housing in Ouled Djellal with adapted passive strategies is analysed through psychometric chart evaluation, in situ measurement campaign and dynamic simulations (EnergyPlus), to understand its thermal behaviour and energy demand, exploring the impact of seven different scenarios with modified passive strategies and parameters. The results show that the actual design temperatures in the typical hottest days are between 30.1 °C and 35.4 °C, while the external temperature is achieving to 47 °C. Moreover, the building consumes 10.43 kWh/m 2 and 19.87 kWh/m 2 for cooling and heating demand respectively. It varies according to the different analysed scenarios. This study can be useful for decision makers and architects in Algeria and abroad, towards the climate-responsive design in housing sector. • Promoting the climate-responsive design in severe climate in term of energy saving. • Adopting a detailed methodological framework to evaluate passive strategies. • Simulating a typical housing in hot-dry climate to validate the model's outcomes. • Drawing attention of architects and decision makers for ideal concepts and results. • Exploring parametric variations of adaptive design model based on dynamic simulation.

Semantic analysis of traditional Persian residential architecture with an emphasis on the role of signs (Case study: Traditional houses in hot-dry climate)

Semantic analysis of traditional Persian residential architecture with an emphasis on the role of signs (Case study: Traditional houses in hot-dry climate)

Stay cool without fossil fuel. A passive eco-cooler for low-income population in informal settlements

With climate change severe events, more and more vulnerable populations suffer from extreme heat waves. This paper presents a hands-on experimental idea for testing vernacular passive cooling strategies using traditional Shisha clay funnels for the Egyptian hot dry climate. Several clay funnels were investigated in terms of shape, size and form. The clay funnels were measured and simulated for their efficiency in accelerating air flow inside residential units and ability to enhance the air velocity if used combined with cross ventilation strategies. Computational Fluid Dynamics (CFD) simulations were conducted in ANSYS Fluent to understand the airflow behaviour inside the simulated test shoe boxes resembling living rooms - using the standard k-∈ turbulence model - for single and multi-units’ configurations. Followed by experimental test cells application for the cooling system and monitoring for testing thermal performance. The simulation results showed significant enhancement in air flow and air speed inside the test room compared to conventional windows, while the test cells monitoring showed an average reduction in indoor temperature and humidity with 2 degrees and 15 % respectively. Further monitoring is needed for other alternations of the eco-cooler funnel design for better performance.

Too Hot to Stay at Home: Residential Heat Vulnerability in Urban India

Rising temperatures may lead to deadly heat waves in India. Combined with a growing urban population and mass production of affordable housing, this can sharply accelerate the demand for space cooling. India’s voluntary Energy Conservation Building Code - Residential (ECBC-R) or Eco Niwas Samhita 2018 limits thermal transmittance of the envelope. This research considers and critiques this approach through building simulation and an analysis of indoor comfort and severity of overheating during the summer months (April-May-June), in hot-dry and warm-humid climate zones. Code requirements neither vary with climate zones, nor is it adapted to future climate conditions. Our building simulations and analysis show that soon (2030s) parts of the country are likely to suffer from overheating 74% of time in summer. A minimally code compliant building would need air conditioning 90% of summer while a highly efficient iteration could reduce this by a third, in the hot-dry climate zone. Further, commonly used envelope assemblies are uncomfortably hot 77% (in the hot-dry zone) and 23% (in the hot-humid zone) of time in summer, on average. This analysis illustrates the vulnerability of current construction techniques to extreme heat and aims to avoid a long-term lock-in of inefficient, high energy consuming residential buildings.

Improving thermal performance of a solar thermal/desalination combisystem using nanofluid-based direct absorption solar collector

Depletion of freshwater resources and reduction of rainfall in arid areas causes water scarcity, which is intensified by population and urbanization growth. In this study, a small-scale solar thermal/desalination combisystem using nanofluid-based direct absorption solar collectors and humidification-dehumidification desalination unit is proposed to supply domestic hot water, space heating, and freshwater demands of a residential building. The dynamic simulation of the system performance in the Hot-Dry climate zone is done using TRNSYS-MATLAB co-simulator. The results indicate that using the proposed combisystem reduces 94.3% and 17% of annual energy consumption for providing domestic hot water and space heating demands, respectively. The freshwater demand is supplied in the range of 11.3% to 100%. In the case of using a flat plate solar collector, the solar fraction for domestic hot water and space heating demands in comparison with nanofluid-based direct absorption solar collectors reduces by 3.7% and 1.7%, respectively. Furthermore, the produced freshwater reduces 18% on average. The payback time using nanofluid-based direct absorption and flat plate solar collectors are 6.4 and 7.8 years, respectively.

Air-conditioning cost saving and CO2 emission reduction prospective of buildings designed with PCM integrated blocks and roofs

The phase change materials (PCMs) in building envelopes effectively reduce cooling loads in buildings. This work explores the thermoeconomic performance of buildings designed with PCM integrated hollow concrete blocks and hollow roofs. The five PCMs were considered, such as HS24 (Hydrated salt), OM21 (organic mixtures), OM30, OM35, and OM46. Thirty various building models are studied with three configurations of PCM integrated concrete blocks (Inner side PCM layer (W-1), Center PCM layer (W-2), and Outer side PCM layer (W-3)) and two configurations of PCM integrated roof tiles (Inner side PCM layer (R-1) and outer side PCM layer (R-2)). The OM30 PCM integrated composite wall and roof tile showed better thermoeconomic performance than other studied PCMs. The building model configuration (BC-F), which is the combination of PCM composite wall (W-3) and PCM roof tile (R-2) exhibited the highest yearly air conditioning cost-saving and the highest yearly carbon emission mitigation in both hot-dry (Jodhpur) and composite (New Delhi). In the hot-dry climate, the building model configuration (BC-F) with OM30 PCM exhibited the highest air-conditioning cost savings with reasonable payback periods and highest CO2 emission reductions compared to other building model configurations studied.

Prediction of early functional outcomes of hemorrhagic stroke

A common limitation of studies on hemorrhagic stroke (HS) outcomes is that authors concentrate exceptionally on clinical data and do not consider environmental factors. There is a rising body of evidence for highly informative value of weather in the forecast. We aimed to predict unfavorable outcomes in patients with HS at the time of discharge from in-patient service in hot dry climate.

Effects of vine top shading on the accumulation of C6/C9 compounds in 'Cabernet Sauvignon' (Vitis vinifera L.) grape berries in northwestern China.

The Xinjiang Uygur Autonomous Region is an arid and semi-arid region with low rainfall and strong sunlight; thus, grape berries in this region accumulate sugar content rapidly, and the ripening process is shorter than that in other regions. Although previous studies illustrated that altered sunlight conditions could influence the aroma profiles of grape berries, less attention has been paid to the effect of vine top shading on volatile compounds under a dry-hot climate. We focused on the effects of vine top shading on the concentrations of linolenic and linoleic acids, as well as their metabolites, the C6/C9 compounds, in grape berries. Four vine top shading treatments at veraison (ripening onset) and post-veraison (skin full coloration) were performed by reducing solar exposure to the grapevines by 20% and 50% respectively. Apart from (E)-2-hexenal in the 20% shading treatment of 2016, (E)-2-hexenal were not promoted by the 50% shading and 20% shading treatments during veraison to harvest in both of the vintages. By contrast, the influence of vine top shading from post-veraison till harvest was different between the two vintages; these C6 compounds were decreased in both of the shading treatments in 2016, whereas most of them were promoted in 2017, possibly related to daily sunshine hours in this period. In addition, the C9 compound nonanal with very low concentration exhibits a significant difference among various treatments by two-factor analysis of variance. As for linolenic acid and linoleic acid, two types of C6 compound biosynthetic precursors, four shading treatments all reduced their concentration, except for linolenic acid in the 50% shading treatment of 2016. Moreover, it appeared to have no apparent correlation between the variations of two precursors and their volatile metabolites, indicating that there is a complex impact of vine shading on C6 compound biosynthesis. Vine top shading at veraison can reduce the accumulation of some C6 compounds in grape berries, but no consistent consequence was attained for the vine shading at pre-veraison. The findings indicate the significance of grapevine solar exposure management at veraison in controlling the level of C6 compounds in a dry-hot region like Xinjiang. © 2021 Society of Chemical Industry.

Feasibility of Reducing Electricity Consumption of Air Conditioning Equipment by Condenser Direct Evaporative Cooling Technology. Example of Case Study in Dubai

The use of air conditioning technology is accompanied by an increase in electricity consumption, which is linked to an intensification of fossil fuel extraction. This in turn calls for developing cooling solutions of higher energy efficiency. The aim of this study is to examine energy consumption reduction of direct evaporative cooling technology for generating cool air in hot-dry climate regions. At the initial stage, already-installed air cooling equipment with a direct evaporative cooling system was studied for the creation of two regression models of electricity consumption representing the “on” and “off” sequences. Water consumption for system operation was taken into consideration. In the following stage, inlet water temperature dependence for pre-cooling purposes for the direct evaporative cooling system was studied. A mathematical model was developed and the subsequent calculations suggested that there is no need to pre-cool water before it enters the system and therefore consume additional energy. Practical application of this study is evaluated based on the case study in Dubai. The results of this study present significant energy saving potential for system operations of the direct evaporative cooling system of approximately 122 MWh per year. The return on investment for the equipment with direct evaporative cooling in case of an office building in Dubai featuring a hot desert climate is around 4.2 years. The purpose of this study is to examine the potential advantage of air cooling equipment with direct evaporative cooling technology compared to cooling equipment without this technology. The results provide the expediency of conducting further research in this area, in particular with regards to analyzing various materials for the adiabatic precooling pads, as well as the possibility of using a newly developed metal precooling pad.

Evaluating the Effect of External Horizontal Fixed Shading Devices’ Geometry on Internal Air Temperature, Daylighting and Energy Demand in Hot Dry Climate. Case Study of Ghardaïa, Algeria

The present study investigates the effect of fixed external shading devices’ geometry on thermal comfort, daylighting and energy demand for cooling and heating in the hot and dry climate of the city of Ghardaïa (Algeria). A parametric analysis was performed by using three software: RADIANCE 2.0 and DAYSIM 3.1 for daylighting simulation and TRNSYS.17 for thermal dynamic simulation. Three shading device parameters were assessed: the spacing between slats, the tilted angle and the slats installation. The vertical shading angle “VSA” is fixed; it is equal to the optimum shading angle measured for Ghardaïa. The simulation results indicate that fixed external shading devices have a significant impact on decreasing the energy demand for cooling; however, they are unable to reduce the total energy demand since they significantly increase heating loads. It was found that fixed external shading devices remove all risks associated with glare in summer by decreasing illuminance close to the window; however, they do not improve daylighting performance in winter because of glare. We note that even if the vertical shading angle “VSA” was the same for all cases, these did not present the same thermal and luminous behavior. This is mainly due to the amount and the way that the solar radiation penetrates space.

Economic feasibility of passive strate gies for energy efficient envelopes of mass-built housing in hot-dry climate

The authors thank the Autonomous University of Baja California and the Master and Doctorate program in Architecture, Urbanism and Design (MyDAUD) for the support provided to carry out this study, the National Council of Science and Technology (CONACyT) for the scholarship provided for the completion of master’s degree studies, as well as the RUBA construction company.

The effect of Urban Heat Island mitigation strategies on outdoor human thermal comfort in the city of Baghdad

Todays, most Iraqi cities suffer from extremely hot-dry climate for long periods throughout the year. However, most urban patterns that exist inside these cities are not suitable for this harsh conditions and lead to an increase in the value of the Urban Heat Island (UHI) index. Consequently, this will increase outdoor human thermal discomfort as well as energy consumption and air pollution in cities. This study attempts to evaluate the effect of UHI mitigation strategies on outdoor human thermal comfort in three different common types of urban patterns in the biggest and most populated city in Iraq, Baghdad. Three different mitigation strategies are used here – vegetation, cool materials, and urban geometry – to build 18 different scenarios. Three-dimensional numerical software ENVI-met 4.2 is utilised to analyse and assess the studied parameters. The input data for simulations process are based on two meteorological stations in Baghdad: Iraqi Meteorological Organization & Seismology, and Iraqi Agrometeorological Network. All measurements are taken in a pedestrian walkway. The results of different scenarios are compared based on their effect on human thermal comfort. Outdoor thermal comfort is assessed according to Predicted Mean Vote index, as mentioned in ISO 7730 standard. This study provides a better understanding of the role of UHI mitigation strategies on human thermal comfort in the outdoor spaces of Baghdad's residential neighbourhoods. This can help generate guidelines of urban design and planning practices for better thermal performance in hot and dry cities.

Effects of Urban Development Patterns on Municipal Water Shortage

While urban areas are being threatened by water shortage due to climate change and rapid population growth, effects of urban development patterns on future municipal water shortage are rarely investigated. We address this aspect of urbanization by assessing the impacts of sprawl vs. high-density patterns on future changes in the sub-annual water shortage intensity-duration-frequency (IDF) relationships. The City of Fort Collins, Colorado, water supply system is chosen as a representative region that is rapidly developing over the last decades. The future water supply is estimated using the Soil and Water Assessment Tool (SWAT) driven with a hot-dry climate model from the statistically downscaled Coupled Model Intercomparison Project, phase 5 (CMIP5) projections. Future water demand is projected using the Integrated Urban Water Model (IUWM) under both sprawl and high-density development patterns. The demonstration study reveals that urban areas under the sprawl development pattern are likely to experience water shortage events with higher intensity, duration, and frequency compared to the high-density pattern. Characterizing impacts of urban development patterns on future water shortage conditions is required for sustainable water management and smart urban growth and can help urban planners and water managers to develop an adaptive path to meet future water demand and decrease the vulnerability of municipal water supply systems to shortage.

Amplified intensity and duration of heatwaves by concurrent droughts in China

Compound hot-dry climate extremes could lead to severer natural disasters and socio-economic impacts compared to individual events. An improved understanding of historical heatwave-drought compounds and their differences compared to heatwaves alone is needed for better predicting the occurrence and impacts of extremes under a changing climate. In this study, we investigated spatiotemporal variations of heatwave-drought compounds using meteorological data from more than 2000 stations in China during 1980–2017, and compared the heatwave intensity and duration in heatwave-drought compounds with that in heatwaves alone. The annual occurrence of heatwave-drought compounds increased significantly during 1980–2017. At the national level, heatwave intensity in heatwave-drought compounds was 34.24 °C ± 4.39 °C, which was higher than that in heatwaves alone of 33.33 °C ± 4.35 °C. The occurrence of long-lasting (duration >7 days) heatwaves accounted for about 34.42% - 50.70% in heatwave-drought compounds, while this ratio was only 11.82% -21.55% in heatwaves alone. The quantitative evaluation of heatwave-drought compounds and heatwaves alone in China highlighted the amplified heatwave severity and duration in heatwave-drought compounds versus that in heatwaves alone.

Sensitivity analysis of a vertical geothermal heat pump system in a hot dry climate

Ground source heat pumps (GSHPs) are considered to provide very efficient air conditioning systems, and this assists in achieving sustainability goals as well as reducing electricity consumption and carbon emissions. The design of such systems, however, depends on the climatic conditions and the geological characteristics of the site; in practice, the optimum design of the system also depends on the characteristics of the surrounding soil. The majority of the research into GSHPs has been focused on cold regions, thus this work is a very useful reference and important in GSHPs’ design in Saudi Arabia and therefore in other hot and arid regions.For the first time in such a hot/dry climate, a rigorous sensitivity analysis method applying the Ground Loop Design software has been employed to analyse 12 parameters that most affect the behaviour of the system. It is concluded that the most important four design parameters are the: thermal conductivity, soil temperature, building load, and fluid flowrate. On increasing these values they have opposing effects on arid environmental conditions, such as those found in the city of Riyadh in Saudi Arabia.In addition, the near-optimum design of a GSHP system in the city of Riyadh in Saudi Arabia has been investigated. The temperature of the water entering the heat pump is an adjustable factor that determines the performance of a GSHP unit. Because of the coefficient of performance of the heat pump, it can also be measured by the value of the entering water temperature. Thus, the entering water temperature (EWT) was selected to be the performance measure of the system, as all the heat transfer processed between the ground heat exchanger components and the surrounding soil is manifested in the entering water temperature. The value of the EWT was fixed both at the baseline and in the proposed design systems, and these were tested over the lifespan of 20 years. The results showed that the length of the ground heat exchanger and power consumption in the proposed design could be reduced by 15% and 1.12% respectively, compared to the baseline system. These results can be used to simplify the design of buildings in similar arid regions worldwide.

Performance enhancement of air conditioner in hot climate by condenser cooling with cool air generated by direct evaporative cooling

This research studied the direct evaporative cooling technique for generating cool air in hot–dry and hot–humid climates. For direct evaporative cooling, three parameters affected the air temperature: feedwater temperature, wet-bulb temperature, and mass ratio of feedwater to circulating air were investigated. When the feedwater temperature was lower than the wet-bulb temperature, in a hot-humid climate, an increase in the mass ratio of feedwater to the circulating air decreased the outlet air temperature. Conversely, if the feedwater temperature was higher than the wet-bulb temperature, in a hot-dry climate, a decrease in the mass ratio was needed to reduce the air temperature. The cooled air obtained could be used for condenser cooling of air-conditioner for performance enhancement. According to a 1 TR air conditioner simulation, lower feedwater temperature resulted in higher energy efficiency ratio. High mass ratio, thus, was recommended in the hot-humid climate area whereas less mass ratio was preferable for the hot-dry climate area. The energy efficiency ratios of the unit with direct evaporative cooling for hot–dry and hot–humid climates ranged from 3.40 to 4.22 and 3.30 to 3.94, respectively, compared to 3.01 for the normal unit. The payback period for the unit with direct evaporative cooling in case of Chiang Mai (hot-humid climate) was around 2.87 year.

Optimizing Building Orientation for Reduced Cooling Load in Northeast Nigeria’s Residential Architecture

Between 1996 and 2005, the domestic sector was responsible for over half (55% -61%) of energy consumption in Nigeria. In addition, electrical energy used for cooling makes a significant contribution to national consumption. In the larger context of climate change and its accompanying adverse effects, it is important for architecture to reduce its global carbon footprint. Developing nations lack sufficient building performance standards, and as a consequence, sustainable building methods are neither pursued nor enforced. Thus, in the absence of high-tech green building practices, this paper seeks to evaluate how simpler passive means of design can be used to reduce cooling energy consumption in Northeast Nigeria’s hot dry climate. DesignBuilder is used to produce different building orientation iterations to evaluate their impact on cooling loads and an ideal building orientation is determined for the region. An optimal orientation of 270° is found to be optimal, as it reduces maximum cooling loads from 11150.95 kwh/yr to 9981.1 kwh/yr, a reduction of energy use of 10.5%.

THE APPLICATION OF PASSIVE DESIGN STRATEGIES AS SUSTAINABLE OPERATION AND MAINTENANCE IN A MODEL CONFERENCE CENTRES (A CASE STUDY OF AMINU KANO CENTRE FOR DEMOCRATIC RESEARCH AND TRAINING (AKCDR&T))

ABSTRACT: This research sought to reduce uncomfortable conditions created by extremes of heat and dryness in order to achieve well balanced indoor and outdoor climate, through the application of passive design strategies in Conference Centre located in hot dry climate of Kano Nigeria. Passive design utilizes natural sources of heating and cooling breezes. It is achieved by appropriately orientating the building on its site and carefully designing the building envelope (roof, walls, windows and floor). External features such as fountain, soft landscaping and proper site planning improves micro climate which in turn helped in achieving good passive design. The methodology employed is case study and relevant information sourced from pertinent literature and the internet was taken into consideration. Research has shown that more than40% of energy consumption in any building is used for cooling and lighting in order to achieve comfort level. In the course of the research, the building was studied to evaluate the use of passive elements that relates to passive lighting and cooling which are the main source of energy consumption such as building envelop, natural lighting, natural ventilation, Site and external spaces, building form, building orientation, wall/window shading and existing of energy source on conference centre building. Research has shown that, the design parameters obtained from field survey are the principal factors responsible for any good passive design of most public building such as conference centre building.

Evaluating Energy Consumption And Loading Of Institutional Buildings In North West-Nigeria

Lack of government policies on efficient use of energy in buildings is one of the limiting factors toward achieving sustainable environment and development. Although, government has been setting targets to increase electricity generation in Nigeria, there is little or no consideration for its efficient usage in buildings. In order to propose an energy efficient office building, energy audit of existing similar structures should be conducted. Thus, this research aims at finding the energy demand of University Senate Buildings in North West-Nigeria (hot dry climate) in order to serve as a bench mark for further researches. Senate Buildings of three universities were studied, namely: Northwest University, Kano (NUK), Bayero University, Kano (BUK) and Umaru Musa Yaradua University, Katsina (UMYUK). Quantitative approach was adopted to carry out the audit and results were recorded as follows: NUK: 258,770.4kwh, BUK: 190,338.24kwh and UMYUK: 190,338.24kwh. The three results indicated high demand for energy by the existing case studies which necessitate researches on how to lower this demand to the barest minimum and to propose more sustainable design approaches.

Performance and Creep Characteristics of Synthetic Geogrids Following Hot Dry Climate.(Dept.C)

Performance and Creep Characteristics of Synthetic Geogrids Following Hot Dry Climate.(Dept.C)