Buildings In Hot Climates Research Articles

Integration of active solar cooling technology into passively designed facade in hot climates

Sustainable buildings have recently become a global priority. In hot climates, meeting the cooling demand in the sustainable buildings is challenging. To meet this demand in office buildings during summer, the study proposed a holistic configuration of applying passive solar design strategies (PSDSs), and then integrating an active solar cooling technology (ASCT) into the facade. Three hot climates, namely, humid subtropical, hot semi-arid, and hot desert, were investigated using a building energy model. First, four PSDSs, window-to-wall ratio (WWR), glazing type, shading devices, and wall material were sequentially applied to the facade. Then, an absorption chiller driven by a solar thermal collector (STC) was integrated into this passively designed façade. The best tilt angle, area, and dimensions of STC were specified for the main façade orientations. Finally, this study provides design guidelines for integrating ASCT into passively designed façade of office buildings in hot climates. The results reveal that WWR has the highest impact on the cooling demand reduction, whereas the least effect results from the shading devices. The passively designed facade reduces the cooling demand by 43.5%–65.7%. The sloped STC at a tilt angle of 30° is the most efficient option for all orientations except the north where the horizontal STC is considered the best. For these tilt angles, STC area required for meeting the cooling demand ranges from 2.88 m2 to 4.5 m2, corresponding to an STC-to-façade width ratio of 74.1%–84.3%. In the case of the vertical STC, the ASCT is unable to meet the cooling demands.

Light, Air, and (No) Sun. Negotiating Illuminance, Ventilation and Insolation Through Architectural Form To Achieve Energy-Efficiency and Comfort in Residential Buildings in Very Hot Climates: Two Case Studies from Muscat, Oman

The discourse on energy-efficient buildings tends to shift out of the realm of architecture and into engineering and programming. In the latter disciplines, sophisticated solutions are developed and introduced to the green building industry. However, such solutions require financial and technical capacities that are only found in technologically highly developed countries. In developing countries and their ever-growing metropolises, a much more robust approach seems appropriate. This paper explores how the energy-demand for creating comfortable interior environments in very hot climates can be significantly reduced by promoting simple and straightforward architectural means. It seeks to relocate the discourse back into the realm of design, where less costly, more feasible and long-lasting solutions can be found. The paper presents two case studies of residential architecture in Muscat, Oman. Through simulations of solar insolation as well as daylight studies, it shows how architectural form can respond to two solar phenomena - heat and light – in such a way that insolation on glazed facades is minimized, while illuminance of interiors is optimized. It claims that this can lead to a new regional architectural idiom that puts the famous modernist credo on its head by stating that energy-efficient buildings in a hot climate zone require “light and air, but no sun”.

A Review of Thermal Design for Buildings in Hot Climates

Most of the developed world currently lives above the tropic of Cancer in cold climate regions. It follows that most of the top architectural firms are from the same countries, and most of their work is based on that experience. Experience that does not travel well to hotter countries. This paper is mainly concerned with the climates of the Middle East region, which are hot in summer and have mild or cold winters, and where the humidity ranges from dry to humid. It is a review of the factors, designs, and solutions that designers sometimes ignore, undervalue, or on the other hand, put too much weight on when working in such climates. An overview of thermal solutions is conducted, and a critique and suitability of each one for hotter climates are offered. Some of the solutions, which are thought to be helpful, have little benefit, especially traditional ones, which are not up to present-day standards and lifestyles. Others, such as courtyards, do more harm than good. A couple of case studies to evaluate houses with and without thermal measures showed improvements of 23-48%. The paper will evaluate architectural, cooling, and building design solutions according to suitability in dry and medium humidity, warm and hot countries.

Reassessment of fenestration characteristics for residential buildings in hot climates: energy and economic analysis

Reassessment of fenestration characteristics for residential buildings in hot climates: energy and economic analysis

Analysis of the performance of an integrated multistage helical coil heat transfer device and passive cooling windcatcher for buildings in hot climates

In a world of increasing population, a pending global energy crisis and the worsening impact of global warming and climate change, there needs to be a focus on re-designing building services to protect occupants at a low-energy cost. Traditional Heating, Ventilation and Air-Conditioning (HVAC) systems do not serve the future of the built environment as they rely on fans which typically constitute 25% of a building's energy consumption. Additionally, even the energy-saving strategies such as using recirculated air in mechanical ventilation systems have posed an occupancy wellbeing issue in the wake of the Covid-19 pandemic by promoting the spread of airborne disease. Therefore, natural ventilation technologies, such as windcatchers, present an advantage over mechanical systems from energy consumption and occupancy wellbeing perspectives. This paper presents the development of a multistage windcatcher with Helical Coil Heat Transfer Device (HCHTD) to enhance its cooling performance for buildings located in hot climates. The evaluation of the ventilation and cooling performance of the windcatcher with HCHTD, through a Computational Fluid Dynamics (CFD) model, includes geometric parametric studies, operating condition analyses and ventilation requirement assessment. The modelling approach was validated using previous works data, resulting in good agreement. This novel concept achieved a noteworthy range of cooling of 8.6 K–14.25 K for a range of wind speeds of 1–4 m/s and a temperature of 39°C, based on typical hot conditions in Australia. The focus of the study was to assess the impact of geometry compactness on the cooling and ventilation performance of the windcatcher with HCHTD. The outcome is that the novel helical coil heat transfer device could offer competitive cooling whilst meeting fresh air requirements, even at low wind speeds, compared to a windcatcher with a straight cylindrical heat transfer device.

Towards Nearly-Zero Energy in Heritage Residential Buildings Retrofitting in Hot, Dry Climates

Retrofitting “nearly-zero energy” heritage buildings has always been controversial, due to the usual association of the “nearly-zero energy” target with high energy performance and the utilization of renewable energy sources in highly regarded cultural values of heritage buildings. This paper aims to evaluate the potential of turning heritage building stock into a “nearly-zero energy” in hot, dry climates, which has been addressed in only a few studies. Therefore, a four-phase integrated energy retrofitting methodology was proposed and applied to a sample of heritage residential building stock in Egypt along with microscale analysis on buildings. Three reference buildings were selected, representing the most dominant building typologies. The study combines field measurements and observations with energy simulations. In addition, simulation models were created and calibrated based on monitored data in the reference buildings. The results show that the application of hybrid passive and active non-energy generating scenarios significantly impacts energy use in the reference buildings, e.g., where 66.4% of annual electricity use can be saved. Moreover, the application of solar energy sources approximately covers the energy demand in the reference buildings, e.g., where an annual self-consumption of electricity up to 78% and surplus electricity up to 20.4% can be achieved by using photo-voltaic modules. Furthermore, annual natural gas of up to 66.8% can be saved by using two unglazed solar collectors. Lastly, achieving “nearly-zero energy” was possible for the presented case study area. The originality of this work lies in developing and applying an informed retrofitting (nearly-zero energy) guide to be used as a benchmark energy model for buildings that belong to an important historical era. The findings contribute to fill a gap in existing studies of integrating renewable energy sources to achieve “nearly-zero energy” in heritage buildings in hot climates.

Building energy performance simulation: a case study of modelling an existing residential building in Saudi Arabia

Saudi Arabia, like many other developing countries, has had extensive experience with rapid urbanisation and infrastructure expansion, especially in the area of buildings. Buildings play an even bigger part, accounting for roughly 80% of total national electricity consumption. Forecasts indicate that domestic energy consumption will rise at a rate of 4 to 5% annually by2030, based on current local energy consumption patterns. A significant portion of this energy consumption growth results from the inefficient use of energy, and absence of coordinated enforcement and stakeholder engagement. This paper presents results of a study performed to propose potential energy-saving and CO₂ reduction techniques for residential buildings in hot climates, by critically examining an existing and recent building types. A model was designed using computer-based simulation software, DesignBuilder (DB), and the energy performance was then validated against the actual collected data. Building related parameters that make the construction systems behave differently in terms of energy efficiency were analysed. Additional simulations were run with the chosen building's shape, fabric, and user behaviour. Thermal insulation in the walls and roof can save about 45% in overall energy consumption, and when combined with other energy efficiency measures (EEMs), a substantial reduction of 67% can be achieved, according to the findings. In the residential sector, improvements in building energy efficiency were obtained from the perspectives of both technological capacity and initiative energy conservation consciousness.

The geothermal potential of underground buildings in hot climates: Case of Southern Algeria

Underground buildings are one of the most effective old and modern techniques, at the same time to meet the trade-off between thermal comfort and low energy consumption in hot and arid climates, through the soil thermal properties, which can be applied as a heat capacitor for moderating indoor temperatures. This research aims to improve the thermal comfort and energy efficiency of underground buildings compared to aboveground buildings in hot and arid climates based on yearly energy consumption. The experimental measurements of soil temperatures at different depths were compared to the numerical results of the Kasuda equation. Furthermore, TRNSYS software simulation findings were validated by monitoring the temperature of an underground room in Ouargla, Algeria, using digital temperature sensors. The findings revealed that an underground structure with a depth of 2.34 m decreases cooling energy demand considerably during the summer season. Furthermore, with and without state support, the investment return time was predicted from 6.5 to 3.25 years, respectively.

Numerical Investigation of the Influence of Vegetation on the Aero-Thermal Performance of Buildings with Courtyards in Hot Climates

Natural ventilation is an energy-efficient way to provide fresh air and enhance indoor comfort levels. The wind-driven natural ventilation in courtyards has been investigated by many researchers, particularly the influence of the spatial configuration and environmental parameters on the ventilation and thermal comfort performance. However, previous research has mainly focused on the courtyard region instead of the indoor spaces surrounding it. Additionally, as a microclimate regulator, courtyards are rarely assessed in terms of the impact of vegetation, including its impact on energy consumption and thermal comfort. Evapotranspiration from vegetation can help lower air temperature in the surrounding environment and, therefore, its influence on the ventilation and thermal comfort in buildings with courtyards should be evaluated. The present study investigates the impact of vegetation on the aero-thermal comfort conditions in a courtyard and surrounding buildings in hot climates. Computational fluid dynamics was employed to evaluate the aero-thermal comfort conditions of the courtyard and surrounding buildings with different configurations of vegetation. The modeling was validated using previous works’ experimental data, and good agreement was observed. Thermal comfort indices were used to assess thermal performance. The study also evaluated the cover, height and planting area of vegetation in the courtyard. The results of this study can help develop tools that can assist the addition of vegetation in courtyards to maximize their effects. Future works will focus on looking at the influence of the strategies on different designs and layouts of courtyards.

Passive building cooling achieved with a new class of thermal retrofit: The liquid vapour phase change material

For a period covering more than half of the last century and until now, the term “phase change material” (PCM) in context of passive building coolingunanimously referred to a class of materials undergoing solid–liquid phase transition in cyclic manner. In contrast to solid–liquid PCMs (SLPCMs), the liquid-vapour phase transition has not been capitalized in a similar way to cool buildings by passive means despite the clear notion that the latent heat of evaporation exceeds the latent heat of fusion by a significant margin. The present work is an endeavour towards offering a new passive cooling system for buildings in hot climate with the help of liquid–vapour phase transition. Unlike existing active evaporative cooling systems, the liquid–vapour PCM (LVPCM) system does not require any external power supply to induce cooling effect. In the hot climate of Delhi, India, a peak temperature dip of 2.22℃ was achieved with the LVPCM system. An average indoor heat gain reduction of 13.56% was realized which reached a maximum value of 20.51% during the experiment. This novel system could overcome the night time heating issue of SLPCM. Furthermore, several additional benefits (such as the use of environment friendly and low-cost materials, ease of installation etc) could make LVPCM a competitive alternative to the prevailing SLPCM technology.

Assessment of Passive Retrofitting Scenarios in Heritage Residential Buildings in Hot, Dry Climates

Retrofitting heritage buildings for energy efficiency is not always easy where cultural values are highly concerned, which requires an integrated approach. This paper aims to assess the potential of applying passive retrofitting scenarios to enhance indoor thermal comfort of heritage buildings in North Africa, as a hot climate, a little attention has been paid to retrofit built heritage in that climate. A mixed-mode ventilation residential building in Cairo, Egypt, was selected as a case study. The study combines field measurements and observations with energy simulations. A simulation model was created and calibrated on the basis of monitored data in the reference building, and the thermal comfort range was evaluated. Sets of passive retrofitting scenarios were proposed. The results (based on the ASHRAE-55-2020 adaptive comfort model at 90% acceptability limits) showed that the annual thermal comfort in the reference building is very low, i.e., 31.4%. The application of hybrid passive retrofitting scenarios significantly impacts indoor thermal comfort in the reference building, where annual comfort hours of up to 66% can be achieved. The originality of this work lies in identifying the most effective energy measures to improve indoor thermal comfort that are optimal from a conservation point of view. The findings contribute to set a comprehensive retrofitting tool that avoids potential risks for the conservation of residential heritage buildings in hot climates.

Low-energy cooling and ventilation refurbishments for buildings in a Mediterranean climate

ABSTRACT In view of the ageing domestic building stock and increasing reliance on fossil fuels for cooling and ventilation of buildings, there is an urgent need for improved design knowledge and sustainable measures such as natural ventilation and passive cooling to mitigate climate change and future proof the built environment. This paper forms an appraisal of a range of low-energy refurbishment measures, i.e. building design alterations and passive systems, which were employed and evaluated in an apartment building in Greece. The applicability of these in domestic buildings in hot climates is assessed and their design implications evaluated. Implementation of wind-catchers, dynamic façades, and evaporative cooling had the highest ventilation and cooling potential, while improvements of the interior layout to allow for new airflow paths could provide further cooling to spaces and solutions to safety.

Effect of Aging on Solar Reflectance of White Cool Roof Coatings: Natural Weathering and the Influence on Building Energy Needs for Different Climate Conditions in Brazil

The use of cool materials on the building envelope is one of the most cost-effective ways to increase indoor thermal comfort conditions in hot climates and decrease the cooling energy needs. Despite the benefit of reducing cooling loads, researches have demonstrated that aging of roof coatings changes the initial solar reflectance (SR), which influences the long term building thermal and energy performance. Thus, this work presents preliminary natural weathering tests performed on samples of nine white coatings exposed to natural weathering for one year in the city of Sao Carlos, Brazil. Solar reflectances were measured with a spectrophotometer before and after exposure, every 3 months, for identifying the effect of aging along the time. The findings showed changes of 13% to 23% on SR after one year of natural weathering, with higher decrease on SR for rougher surfaces. The cleaning process restored from 90% to 100% of the original SR, which means maintenance can be an effective solution to restore the initial SR. Simulations indicated that roofs with higher solar reflectance increase indoor thermal comfort conditions and decrease the cooling energy need for buildings in hot climates, but the aging of white coatings increased the cooling energy needs along the time

Experimental characterization of reflective coating material for cool roofs in hot, humid and dusty climate

Considerable energy is used for cooling buildings in hot climates like those found in Gulf Cooperation Council (GCC) countries. Designing building envelopes for the purpose of saving energy can necessarily help reduce the building's operating expenses and therefore energy demand over time. For roofing systems, a research project was recently conducted to assess experimentally and numerically the performance of the roofing systems. This paper presents the experimental results of this project. Cool/reflective/white roofs use reflective materials or coatings to reflect a portion of the incident solar radiation. This results in lowering the surface temperature of the cool roofs compared to black roofing systems. As such, cool roofs help reduce the cooling loads during the summer season. This paper presents the test results of characterizing the short-wave solar reflectivity of a reflective roofing material that can be used in cool roofs of Saudi buildings. A Reflective Coating Material (RCM) that is commercially available in the GCC markets was used in this study. Also, the reduction in the solar reflectivity due to dust and dirt accumulations on the surface of the RCM was investigated in this study when this coating was exposed to a dusty and polluted climate of Jubail Industrial City (JIC). As well, the effect of applying different cleaning operations on the solar reflectivity of the RCM was investigated. The test results showed that dust/dirt can significantly contribute in reducing the short-wave solar reflectivity of the RCM. For the RCM subjected to the natural weathering conditions at different exposures times, the results showed that a maximum enhancement of 5% in the short-wave solar reflectivity was achieved, as a result of conducting air plowing process that simulates the wind action. Additionally, a maximum enhancement of 45% in the short-wave solar reflectivity was achieved as results of conducting water cleaning/rinsing process that simulates the rain action and as well conducting washing with dishwashing detergent that simulates homemade cleaning. Furthermore, conducting professional cleaning has resulted in insignificant enhancement in the short-wave solar reflectivity compared to conducting homemade cleaning. Finally, this paper provides a test procedure for characterizing the dust concentration/intensity on the surface of the RCM at different exposure times to the natural and polluted climate. This test procedure can easily be applied on different types of reflective roofing materials and membranes that can be used in cool roofs.

Evaluation of the Integration of the Traditional Architectural Element Mashrabiya into the Ventilation Strategy for Buildings in Hot Climates

This paper reviewed related research works and developments on the traditional architectural element “mashrabiya” focusing on its history, design and structure, typology, and functions in hot climates. Moreover, the paper assessed the effect of the traditional mashrabiya on the indoor thermal environment and thermal comfort in a selected case study building. For this purpose, two similar rooms were investigated in a selected historic building with abundant mashrabiyas located in the Makkah Region, specifically in Old Jeddah, Saudi Arabia. The field tests were conducted during a typical hot summer month with two different configurations. The study demonstrated that opening the mashrabiya allowed more airflow into the room during the day and reduced the indoor temperature by up to 2.4 °C as compared to the closed mashrabiya. Besides, the building envelope played an important role in preventing the high fluctuation of the indoor air temperature, where the fluctuation of the rooms air temperature ranged between 2.1 °C and 4.2 °C compared to the outdoor temperature which recorded a fluctuation between 9.4 °C and 16 °C. The data presented here can be used for the future development of the mashrabiya concept and the potential incorporation with passive cooling methods to improve its design according to the requirements of modern buildings in hot climates. Moreover, further studies and tests on mashrabiyas under different climatic conditions are required. Also, the different strategies or materials can be incorporated with mashrabiyas in order to improve its thermal performance.

A Study of Design Variables in Daylight and Energy Performance in Residential Buildings under Hot Climates

In Saudi Arabia, residential buildings are one of the major contributors to total energy consumption. Even though there are abundant natural resources, it is somewhat difficult to apply them to building designs, as design variables, due to slow progress and private issues in Saudi Arabia. Thus, the present study demonstrated the development of sustainable residential building design by examining the daylighting and energy performance with design variables. Focusing on the daylighting system, the design variables were chosen, including window-to-wall ratios (WWR), external shading devices, and types of glazing. The illuminance level by these design variables in a building was evaluated by using daylight metrics, such as spatial daylight autonomy and annual sunlight exposure. Moreover, the building energy consumption with these design variables was analyzed by using energy simulation. As a result, the daylighting was improved with the increase in WWRs and the tinted double glazing, while these design options can cause overheating in a residential building. Among types of glazing, the double pane windows with a low-E coating showed better energy performance. Based on the results, it is necessary to find the proper design variables that can balance the daylighting and energy performance in residential buildings in hot climates.

Urban built context as a passive cooling strategy for buildings in hot climate

This paper presents a systematic evaluation of the impact of the built urban context on the cooling energy performance of buildings subjected to extreme hot weather conditions. The proposed approach combines building energy modeling with an extensive parametric variation and statistical analysis scheme. It provides a direct quantification of inter-building shading on energy performance, with an emphasis on the cooling demand patterns for buildings of different types and sizes. Results show that the combined effects of urban context height, distance, and orientation can lead to significant reductions in cooling demand, reaching up to 26% for total cooling loads and 24% for peak cooling loads. The observed savings are particularly notable for residential buildings, making them an ideal target for urban development strategies that aim to leverage inter-building shading effects for energy conservation purposes. Moreover, an in-depth analysis of peak loads illustrates how the density and compactness of the urban form can be used as passive design strategies to reduce the load, and hence, the size of air conditioning systems. Finally, the paper explores how to translate the gained knowledge to design guidelines, bridging the gap between theory and practice.

Building envelope and energy saving case study: a residential building in Al-Riyadh, Saudi Arabia

Abstract Around the world, most energy is consumed by buildings; residential buildings consume 40% of energy globally. In the Kingdom of Saudi Arabia (KSA), buildings consume 50% of all energy, and 70% of the buildings in the KSA are not insulated well. Creating an envelope is a key to decreasing energy consumption and providing thermal comfort and healthy internal spaces. Thus, the main aim of this study is to test the effect of selected passive cooling strategies by using a simulation program to evaluate a variety of envelope (floor, external and internal walls and roofs) thermal characteristic proposals to create an eco-interior space, to provide the most comfortable conditions for users and to save energy in buildings in hot climates in Riyadh, Saudi Arabia. One residential building case was selected, and some of the passive cooling strategies were tested. Simulation software—Design Builder—was used to calculate the total energy consumption in 1 year and compare the results before and after applying these strategies to the selected residential building.

Model Simplification on Energy and Comfort Simulation Analysis for Residential Building Design in Hot and Arid Climate

Accurate building physics performance analysis requires time-consuming, detailed modeling, and calculation time requirement. This paper evaluates the impact of model simplifications on thermal and visual comfort as well as energy performance. In the framework of dynamic zonal thermal simulation, a case study of a residential building in hot climate is investigated. A detailed model is created and simplified through four scenarios, by incrementally reducing the number of thermal zones from modeling every space as a separate zone to modeling the building as a single zone. The differences of total energy and comfort performance in the detailed and simplified models are analyzed to evaluate the grade of the simplifications’ accuracy. The results indicate that all simplification scenarios present a marginal average deviation in total energy demand and thermal comfort by less than 20%. Combining rooms with similar thermal features into a zone presents the optimal scenario, while the worst scenario is the single-zone model. Results showed that thermal zone merging as a simulation simplification method has its limitations as well, whereas a too intensive simplification can lead to undesired error rates. The method is well applicable in further early-stage design and development tasks, specifically in large-scale projects.

Environmental impact of cool roof paint: case-study of house retrofit in two hot islands

Cool roofs save energy and are particularly suited for low rise buildings in hot climates. This paper presents results of potential energy savings for existing houses in two islands (Sicily and Jamaica) based on validated thermal models. It also presents the lifecycle environmental impact of the cool paint focussing on both the midpoint and endpoint impact categories and compares these with thermal insulation impact. It was found that significant net energy benefits are possible in both locations by a cool roof, more pronounced in Jamaica, which has no heating demand; savings are comparable with thermal insulation reductions. The environmental impact of cool paint is lower than a variety of thermal insulation materials with the exception of water depletion potential. The main hotspots of the cool paint are the production of the polymer followed by the production of the pigment.