Buildings In Hot Climates Research Articles

Energy efficient design of buildings in hot climates through cooling of the envelope

The building envelope can afford many enhancements for lowering the cooling load in hot regions. In this paper, an active upgraded model utilizing an evaporative system to cool the envelope will be tested in the relatively humid climate of the coastal area of the Arabian Gulf. A couple of buildings were erected for this purpose. One was fully enclosed by a secondary structure around it, and the gap between the two was cooled using an evaporative cooler. This was compared to the second, which was insulated according to Dubai Municipality standards. A third comparison was also performed, which concerned the standalone secondary envelope with no evaporative cooling. The interior of all three cases was cooled using DX window-type air conditioners, and the power consumption measured. Thermal simulations were performed on similarly designed models using Ecotect 5.5 to see how each system would perform in full-scale functioning buildings. The measured tests on the building models showed a reduction of electrical consumption in both upgrades compared to the regulation insulated reference. The secondary envelope provided savings of 40 % and 47.3 % in the hot months of June and July, while the evaporative solution saved 52.1 % and 53.7 %, respectively. The simulation of a full-size building over the entire year showed the secondary envelope saving 48.9 % and the evaporative assisted 57.15 %.

Energy Flexibility Strategies for Buildings in Hot Climates: A Case Study for Dubai

This paper presents a case study of energy flexibility strategies for a building located in the hot climate of Dubai, a type of climate in which energy flexibility has been under-researched. Energy flexibility is changing the routine-consumption profile and deviating from the normal operation of the building by the users to manage the variability in the load profile and cost of electricity. The three flexibility strategies being considered are based on the modulation of the indoor air temperature setpoint profile while considering different marginal costs for electricity. The main objective is to quantify the energy storage flexibility of each strategy and evaluate its impact on the system ramping and load factor. The study was carried out utilizing a grey-box, resistance–capacitance model of the building, which was validated against experimental measurements. This study is the first to use the following five indicators simultaneously: load factor, system ramping, storage capacity, peak-period demand reduction, and cost savings. Combining these indicators helps building facility managers and distribution system operators (DSOs) better understand the implications of implementing a specific flexibility strategy in a building or a group of buildings. When comparing the indicators of each strategy with each other, it was observed that depending on the amplitude of the change in the electricity cost signal during the peak period, a significant cost reduction of more than 25% could be achieved through the implementation of specific flexibility strategies compared with the normal baseline operating condition.

A novel hybrid passive cooling system for providing thermal comfort conditions and reducing energy consumption in buildings in hot climates

In the present study, the performance of a novel hybrid passive cooling system was studied analytically and numerically in terms of its ability to achieve thermal comfort conditions, produce electricity, and reduce energy consumption. The new hybrid system that has been proposed in this study consists of a photovoltaic solar chimney (SC-PV) system, which in turn consists of a solar chimney (SC) combined with photovoltaic panels (PV). An underground space (UGS) system connects to the photovoltaic solar chimney (SC-PV) system through a residential room. This novel hybrid system is a completely new passive cooling system that is called SC-PV-UGS in the present study. The present system's performance has been studied in hot and moderate climates. The results indicated that the SC-PV-UGS system can provide thermal comfort conditions for the room's residents. The total electricity produced during the hours of solar radiation for the three test days in the hot climate was 310 kWh, while it was 329 kWh in the moderate climate. The total annual electricity produced by the SC-PV-UGS system for the hot climate was 2024 kWh, and for the moderate climate, it was 2318 kWh. The total cooling demand in a hot climate was reduced to 339 kWh, which is 55.9 % of the total cooling demand of the conventional non-passive system.

Energy optimization for Façade retrofit design of residential buildings in hot climates using advanced materials

Global warming has adversely affected the building sector in many countries. Energy retrofit strategies for existing buildings have been developed to combat this issue, including advanced facade system coatings. This study examines how advanced coatings such as PCMs, thermochromics, and cool materials can be effectively used to enhance the thermal behavior and energy performance of existing facades in hot climates. It aims to suggest the optimal combinations of such materials for the façade retrofit design of a typical low-rise residential building in hot climates. Using optimization, Design Builder software is utilized to assess the thermal behavior and energy performance of a combination of advanced materials used. The results revealed that the arrangement of exterior wall layers, thickness and placement of thermal insulation, and the material used in the façade outer layer have a significant effect on the annual energy consumption. Applying coatings with high reflective values as an outer layer of facades can reduce monthly surface temperatures by 2.62 °C in summer and annual cooling loads by 13.78 %. Using PCM coating as an inner layer of the façade improves indoor temperatures by 1.83 °C during different seasons and decreases annual cooling demands by 13.23 %. Finally, the optimal combination of such materials for the energy retrofit design of a typical residential building with three conventional façades has been defined.

Cooling load prediction of a double-story terrace house using ensemble learning techniques and genetic programming with SHAP approach

Since the cooling systems used in buildings in hot climates account for a significant portion of the energy consumption, it is very important for both economy and environment to accurately predict the cooling load and consider it in building designs. This study aimed to maximize energy efficiency by appropriately selecting the features of a building that affect its cooling load. To this end, data-driven, accurate, and accessible tools were developed that enable the prediction of the cooling load of a building by practitioners. The study involves simulating the energy consumption of a mid-rise, double-story terrace house in Malaysia using building information modeling (BIM) and estimating the cooling load using ensemble machine learning models and genetic programming. Categorical Boosting (CatBoost), eXtreme Gradient Boosting (XGBoost), Light Gradient Boosting Machine (LightGBM), and Random Forest (RF) models have been developed and made available as an online interactive graphical user interface on the Streamlit platform. Furthermore, the symbolic regression technique has been utilized to obtain a closed-form equation that predicts the cooling load. The dataset used for training the predictive models comprised 94,310 data points with 10 input variables and the cooling load as the output variable. Performance metrics such as the coefficient of determination (R2), root mean squared error (RMSE), and mean absolute error (MAE) were used to measure the predictive model performances. The results of the machine learning models indicated successful prediction, with the CatBoost model achieving the highest score (R2 = 0.9990) among the four ensemble models and the predictive equation. The SHAP analysis determined the aspect ratio of the building as the most impactful feature of the building.

Electrochromic Glazing and Evaluation of Visual and Non-Visual Effects of Daylight: Simulation Studies for Brasilia – Brazil

The employment of electrochromic glazing can be a solution to balance circadian lighting and avoid glare. This can be achieved by controlling daylight entering the room and may be useful within the context of highly glazed facades in buildings in hot climates. Nevertheless, the use of this technology is rarely discussed in this context. In this regard, the aim of this study is to investigate the electrochromic glazing for the lighting conditions, including visual and non-visual effects within the luminous context of Brasilia, Brazil. The method consisted of computer simulations of a representative highly glazed non-residential room with the comparison of electrochromic glazing and conventional clear glass. Climate Studio was used to evaluate the visual effects of light for the entire year, and ALFA for the evaluation of melanopic daylight illuminance, vertical illuminance, and melanopic daylight efficacy ratio (mel-DER) in four days, including two solstices and two equinoxes encompassing the beginning of the four seasons. Results for the electrochromic glazing showed a better balance between a minimum threshold of 250 lux of mel-EDI without exceeding 1,500 lux of vertical illuminance in comparison with the clear glass. This was achieved in 33.33% of the hours for the north, against 27.78% of the hours for the east, 29.17% for the west, and 24.72% for the south. For the clear glass, this balance was achieved in only 9.17% of the hours for north, 10.28% for east, 12.22% for west, and 15% for south. Regarding the spectrum, higher results of melanopic daylight efficacy ratio were observed for the clear glass over the four simulated days. The main conclusion was that the electrochromic glazing was capable of providing a better balance between visual and non-visual requirements and can be a suitable solution for highly glazed facades in Brasilia. Nevertheless, particularly for the north orientation, the supply of circadian lighting can be jeopardized when the electrochromic glazing remained at the dark state.

An experiment and simulation on a solar-regenerated dehumidifier fabricated from composite desiccant coated fin-tube heat exchanger

Thermal environment in buildings in hot climate is conditioned for comfort by air-conditioning that is energy intensive. Presently, most air-conditioning systems in Thailand and other countries in Southeast Asia use electricity-driven vapor compression systems to cool down the air to the set-point temperature. Latent load due to condensation of air humidity forms a large part of the air-conditioning load. This paper presents the results of experiment and simulation on a dehumidifier constructed from a water-to-air heat exchanger coated with a composite desiccant of SB15 mesoporous silica gel and LiCl, regenerated by low-temperature solar heated water. The results include values of dehumidification performance indices, a conclusion that the optimum cycle duration for dehumidification is close to 200–240 s, and that the effectiveness of moisture removal increase with the regeneration temperature of up to 70 °C. The dehumidifier can from a part of an air ventilator that will substantially reduce cooling load of air-conditioning. The results also highlight the significance of simulation-based analysis, specifically regarding the use of robust mathematical models.

Comparative Investigation of the Energy Efficiency of Mini-Split Air Conditioning with Variable Refrigerant Flow Systems for Office Buildings in Hot Climate.

Comparative Investigation of the Energy Efficiency of Mini-Split Air Conditioning with Variable Refrigerant Flow Systems for Office Buildings in Hot Climate.

Judicious design solutions for zero energy school buildings in hot climates

The concept of net-zero energy, with its holistic consideration of energy-efficient passive, active, and renewable energy systems, is a critical step toward decarbonizing the built environment. This work aims to assess the feasibility of net-zero energy schools in hot climates and propose practical and realistic design solutions. The design of a net-zero energy school was developed and analyzed using DesignBuilder software in hot-humid, hot-dry, and warm-humid climatic zones in Oman. A multiphase methodology was followed, including data collection, an energy audit, fieldwork measurements, and energy simulation modeling. Integrating judicious passive design strategies such as thermal insulation for walls and roofs besides high-performance windows resulted in moderate potential reductions in energy cost and consumption in all climatic zones. Considering active design strategies like light-emitting diode (LED) lights, lighting control, and variable refrigerant volume/variable refrigerant flow (VRV/VRF) air conditioning systems resulted in additional reductions in energy cost and consumption. For the energy cost, the reductions were estimated at 29.9%, 29.5%, and 25.9% in the hot-humid, hot-dry, and warm-humid climatic zones, respectively. The corresponding reductions in energy consumption reached 28.53%, 27.90%, and 25.14%. Integrating a photovoltaics (PV) system aiming to reach the net-zero energy status supplied the school with demanded energy and managed to export 42.78%, 43.53%, and 45.75% to the national grid in the hot-humid, hot-dry, and warm-humid climatic zones, respectively. Similar reductions were achieved for CO2 emissions and energy costs.

Optimizing Energy Efficiency in High-Rise Residential Buildings in Abu Dhabi’s Hot Climate: Exploring the Potential of Double Skin Façades

This study investigates energy efficiency in high-rise residential buildings in Abu Dhabi, where the increased use of glass building façades has led to increased air-conditioning costs due to heat gain. The research focuses on evaluating the type of glass and the appropriate cavity between glass façades to minimize energy consumption while incorporating sustainability and innovative design principles. To achieve these objectives, this study employs a Double Skin Façade (DSF), a high-performance façade that adapts to the external climate conditions to fulfill internal cooling load requirements and meet occupants’ needs. Data were collected through an online survey distributed among residents of a selected residential tower, and a combination of qualitative and quantitative approaches was utilized to analyze the gathered information. The selected case study was analyzed using Energy Plus simulation software using the existing data and available details. The analysis aimed to identify the optimal DSF design that significantly enhances energy efficiency. The findings of this study emphasize the substantial impact of the optimum DSF design on energy efficiency in high-rise residential buildings. Through modeling existing data and comparing them with new model results for each variable, this study demonstrates that a DSF with a 35 cm cavity, comprising a double-glazed single skin layer in the interior and a Low-E double-glazed single skin layer as an outer layer, can reduce overall air-conditioning energy consumption by over 25%. These outcomes provide valuable insights into implementing DSF as a solution to address the unique energy challenges presented by high-rise residential buildings in hot climates.

Evaluation of thermal and energy performance of cool envelopes on low-rise residential buildings in hot climates

Evaluation of thermal and energy performance of cool envelopes on low-rise residential buildings in hot climates

Experimental Investigation on the Performance of a Dehumidifier Constructed from a Water-to-Air Heat Exchanger Coated with Composite Desiccant of Mesoporous Silica Gel and LiCl

Thermal environment in buildings in hot climate is conditioned for comfort by air-conditioning that is energy intensive. Presently, most air-conditioning systems in Thailand and other countries in Southeast Asia use electricity-driven vapor compression systems to cool down the air to the set-point temperature. However, latent load due to condensation of air humidity forms a large part of the air-conditioning load. This paper presents the results of experiments on a dehumidifier constructed from a water-to-air heat exchanger coated with a composite desiccant of large-pore mesoporous silica gel and LiCl, regenerated by low-temperature hot water. Moisture removal capacity (MRC), dehumidification capacity (DC), thermal coefficient of performance (COPth), and an equivalent air conditioning load of dehumidification (EALD) are comparative quantitative parameters derived from experimental results and are studied in this research. The composite desiccant requires low-temperature water for regeneration and offers a higher rate of vapor adsorption and desorption that leads to a shorter required desiccant dehumidification cycle time. The results demonstrate that the dehumidifier is able to effectively reduce moisture in ventilation air and substantially reduces the cooling load of air-conditioning.

Gendered geography of energy consumption in the Netherlands

Household energy consumption (HEC) significantly impacts global greenhouse gas emissions and can trigger fuel and energy poverty among vulnerable households. Due to environmental policies and geopolitical turmoil limiting the energy supply, HEC needs to be curbed. This urges the identification of most energy-dependent consumers at different locations and the particular life circumstances that trigger such a high level of dependency. A gender perspective can provide insights into the life circumstances of households. Applying a geographically weighted regression model on HEC, including explanatory parameters on gender composition, age, ethnicity, income, home ownership, microclimate, urban morphology and land cover, the results show significant variations in HEC of gender groups in 87% of Dutch residential zones. Women with an immigration background (20%), children younger than 14 years old -presumably single mothers (14%), old buildings in hot climates (10%), or high income (9%) are the most energy-dependent gender groups in a significant portion of residential zones. So are the men in large-size households (18%) and older-than-65-years men in rural areas (8%). The study offers discussions on the results and a series of policy recommendations.

Energy and thermal analysis of DSF in the retrofit design of office buildings in hot climates

ABSTRACT In recent decades, the energy retrofit design of buildings has been one of the most effective methods to achieve high-performance buildings. The government office buildings in Iran account for 15% of the non-residential building sector; hence, energy retrofitting of existing office buildings could effectively reduce total energy consumption and Carbon dioxide emissions. This study aims to evaluate the effect of various facade systems with cool materials on the thermal behavior and energy performance of a typical existing office building in a hot climate. The proposed hybrid retrofit method combines design and energy retrofit strategies while evaluating the effects of different workspace layouts and facade systems on external surface temperatures and total energy consumption. Applying such a method, the most optimal design and energy retrofit strategies were selected using a combination of optimization and scenario-based approaches. The results showed that using double-skin facades could reduce annual energy consumption and Carbon dioxide emissions by 63%. Moreover, the results indicated the most efficient types of cool coatings materials for reducing cooling loads.

Sustainable façade cladding selection for buildings in hot climates based on thermal performance and energy consumption

Façade cladding system is essential contributor to the sustainable performance of buildings. Holistic investigation of building facade cladding performance with respect to the regional microclimate is paramount and can contribute to an under investigated research area. The research aims at analyzing the different building facade cladding systems and developing sustainable design guidelines for selecting efficient facade cladding system in hot climates. To achieve this goal, the multi-criteria method of order of preference by similarity to ideal solution is utilized to evaluate experts’ preference of façade cladding according to essential selection criteria, and an integrated environmental solutions-virtual environment simulation technique is applied to analyze thermal performance of the different cladding systems. The findings indicate that stone system is the most preferable cladding material with the highest relative closeness compared to the aluminum composite panel and plaster systems. The recommended façade system is the stone cladding which can reduce the cooling load by 4% and 1.5% compared to the aluminum panel and plaster systems, respectively. Simultaneously, it is found that polyurethane board material reduces the cooling load by 3.8% compared to sandstone with expanded polystyrene. Fire risk ranked at the top of the selection sub-criterion. The simulation demonstrates that fire risk related to the aluminum panel system can be alleviated by using high ignition point insulation materials such as mineral fiberglass and glass wool. Therefore, gravel gray stone cladding system with a cavity and mineral fiberglass is recommended in hot climates for its superior thermal performance and fire resistance.

Phase change material coupled building envelope for thermal comfort and energy-saving: Effect of natural night ventilation under hot climate

Incorporating phase change material (PCM) into buildings in hot climates is an excellent strategy for better thermal comfort and energy-saving in future smart cities. Nevertheless, PCM elements suffer from adverse temperature behaviour at night due to the dissipation of stored diurnal heat. Night ventilation has been proposed as a promising solution and clean strategy for decreasing indoor building temperature at night and increasing PCM benefits in the following cycle. In this study, the effect of the natural night ventilation (NNV) period on the thermal performance of a room-integrated PCM is investigated experimentally under hot summer conditions in Iraq. Six NNV periods (with 1 h increment) are studied for six consecutive days in terms of average indoor and operative temperature reduction. Moreover, the work is extended to study the average heat gain difference in each day cycle to show the contribution of PCM to energy-saving. The results showed a slight enhancement in the average indoor air temperature of the PCM room compared with another identical no-PCM room regardless of the NNV period due to high outdoor ambient temperature at night. However, NNV for 4 h can reduce the average indoor air temperature by 28.6% compared with 1 h of NNV, whereas a slight extra reduction was achieved for 5 and 6 h. Besides, NNV slightly affected the operative temperature at night against no impact during the day, which was more influenced by the solar radiation and high diurnal ambient temperature. The results further revealed that a total average heat gain difference of 63.1–87.9 W was achieved, in which the roof contributed by more than 44% in each cycle. • A PCM coupled building envelope is studied experimentally under severe hot climate. • The effect of NNV on PCM behaviour is evaluated considering the AITR and OTR. • Four-night hours of NNV could lower the indoor temperature of the PCM room to a limit. • Total AHGD of PCM room decreased by 63.1–87.9 W, and the roof contributed by 44%. • Diurnal ambient temperature and solar radiation had influenced the daily AHGR more than NNV.

Comfort and economic aspects of phase change materials integrated with heavy-structure buildings in hot climates

This paper examines the economic viability and efficacy of phase change materials in improving the thermal comfort of inhabitants in heavy-structure buildings, with different wall characteristics, under hot-dry and extremely hot-dry conditions. The efficacy is assessed in free-floating mode (in terms of exceedance hours) and air-conditioning mode (in terms of cooling demand reductions) for six-phase change materials with melting temperatures of 21–31 °C. The simulation model is developed using dedicated building simulation software and validated against the present indoor experiment and an outdoor published experiment. The results indicated that the best material in the free-floating and air conditioning modes is the materials with melting temperatures of 29 and 25 °C, respectively. The phase change material achieves 373 reductions in the exceedance hours more than the thermal insulation when integrated into a wall with a thermal resistance of 0.5m2K/W. As the thermal resistance of the building envelope increases from 0.3 to 1.02m2K/W, the PCM efficacy continually decreases. Also, the reduction in exceedance hours declines from 52.8 to 9.24% as the climate changes from hot-dry to extremely hot-dry. Remarkably, combining a thin 1 cm layer of phase change material and a 3 cm thermal insulation layer reduces the exceedance hours by 65.5%, the air conditioning energy by 27.2%, and the payback period by 54%.

Thermal mass impact on energy consumption for buildings in hot climates: A novel finite element modelling study comparing building constructions for arid climates in Saudi Arabia

Contradictory conclusions have been reported on whether thermal mass reduces or increases energy demand in hot and cold climates. A novel approach to measuring the impact of thermal mass on the building’s energy consumption is presented. The method aims to better represent reality and applies two different control conditions simultaneously in a numerical model: the first condition, which has been used in past studies, adjusts the internal boundary condition based on the time duration of heating/cooling activation (simulating an occupancy pattern) and the second, which has not been used in past studies, adjusts the internal boundary condition based on both the time duration and the internal temperature (simulating an occupancy pattern and the thermostatic control system). When investigating the impact of thermal mass on the internal temperature in a scenario where no heat is transferred into the building, the high thermal mass outperforms the low thermal mass, showing a time-shifting effect, long time lag, and small decrement factor. However, when modelled using the method presented in this paper, high thermal mass results in greater energy consumption during summer and winter periods in Saudi Arabia. During transition seasons where temperature swings occur on either side of the indoor set-point temperatures, thermal mass reduces thermal transmission. The impact of thermal mass is also investigated for several climatic conditions in Saudi Arabia. Simulation results show that an internally exposed thermal massive wall section results in greater energy consumption when compared to a similar building with isolated thermal mass (i.e. insulated internally). This is due to the fact that even though the internal temperature inside the building is being cooled/warmed up to the set-point, the thermal mass continues to transfer heat that is absorbed by the building’s fabric from/to the interior, placing a greater demand on the cooling/heating system. Over the course of a year, however, the impact of thermal mass is negligible when compared to other factors, such as the insulative properties of the building’s fabric.

Field measurement and numerical investigation of natural cross-ventilation in high-rise buildings; Thermal comfort analysis

The importance of climate change mitigation and energy efficiency as a growing global concern has intensified the development of techniques to reach and improve thermal comfort and energy efficiency of buildings. The study of the effect of the height of the openings on the internal natural airflow in one-story buildings can be found in many studies; However, studies on the effect of this important factor on providing thermal comfort in high-rise buildings equipped with DSF are not available. This paper focuses on natural-ventilated buildings based on wind-driven and buoyancy-driven forces. The aim of this study is to use passive strategies in high-rise office buildings in hot and dry climates. In this research, two methods of field studies and numerical modeling have been used in order to provide accurate results. In order to achieve optimal patterns in the design of natural-ventilated buildings; CFD simulation and PMV thermal comfort index have been used in the evaluation of various configurations. The results of the present study show that although the cooling energy demand in high-rise buildings in hot climates is high and the use of natural ventilation systems is beneficial, but these systems alone are not able to provide thermal comfort conditions. However, the accurate and correct location of the openings is effective in improving thermal comfort by increasing the volume flow.

Review on integrated photovoltaic-green roof solutions on urban and energy-efficient buildings in hot climate

• A review was made for 157 and 28 papers of GR and PV/GR systems, respectively. • The potential research gaps of GR and PV/GR were specified in different climates. • The GR key factors are LAI, soil depth, insulation, irrigation and coverage ratio. • GR type, irrigation and plant features are the common factors for GR and PV/GR. • The vegetation, urban and irrigation factors aren't studied enough in hot climate. Climate change and urban heat islands (UHIs) pose mounting threats to built-up areas. In this regard, photovoltaic panels and green roof systems (PV/GR) can offer numerous benefits towards promoting environmentally sustainable cities. This review examines the benefits of GR systems, integrated PV/GR systems and their optimal design factors; research gaps in urban scales and building scales in hot climates are highlighted. A systematic review was undertaken on published papers from the Scopus database that investigated the effect of GR (157 papers) and PV/GR systems (28 papers) that addressed UHI mitigation and how Energy-Saving and Indoor Thermal Comfort (UH-ES-ITC) was achieved in urban buildings. It has been found that GR and GR/PV systems have a positive impact on improving dominant parameters in hot arid climates, especially on the building scale. Unfortunately, there are not many studies that investigate GR/PV systems on coupling scales. This review highlights the research gaps concerning the method, scale, climate, target, factors and parameters of this integration in different climate zones. The results would be valuable for researchers and urban planners to guide research implementation and future research.