Cooling Energy Consumption Research Articles

Experiments on the cooling effect of modular vertical greening on double-glazed façade in summer

Double-glazed façades (DGFs) increase the indoor temperature and energy consumption in summer. Vertical greening systems have significant cooling effects, but most are used on exterior walls. This study combines DGF and modular vertical greening to propose a double-glazed green façade (DGGF) and investigates its thermal performance. Based on the construction of a DGGF model, comparative experiments were conducted in two identical experimental rooms. The DGGF could reduce the indoor temperature by 4.9 °C or 2.9 °C compared to the DGF or the DGF with louver shading, which saved 12% of the cooling energy consumption. Ventilation inside the double glazing enhances the cooling effect of the DGGF, and the indoor temperature can be reduced by 2.3 °C compared to the DGGF with no ventilation. Plant activities play an important role in maintaining the thermal microclimate inside the DGGF, e.g., photosynthesis absorbs solar radiation, and evapotranspiration transfers sensible heat to latent heat. The cooling mechanism of the DGGF was analyzed, and its heat exchange process was explored. This paper verifies the feasibility of applying modular vertical greening in DGFs and proves that DGGFs have a better insulation effect than DGFs with or without louvers.

Novel Thermal-Aware Green Scheduling in Grid Environment

The rising energy consumption of large-scale distributed computing systems raises operational expenses and has a negative impact on the environment (e.g. carbon dioxide emissions). The most expensive operating cost aspect in data centers is the electricity consumption for cooling purposes (DC). Inefficient cooling causes excessive temperatures, which leads to hardware breakdown. To solve this issue, novel thermal-aware green scheduling algorithms were developed to dramatically reduce cooling energy consumption costs while avoiding high thermal stress conditions such as big hotspots and thermal violations while preserving typical competitive performance. As a result of this research, the novel thermal-aware green scheduling algorithms can save cooling electricity usage during job execution when compared to nongreen scheduling methods. Thus, the green scheduling algorithms clearly outperform nongreen scheduling algorithms in terms of cooling power usage effectiveness.

An Analysis of Urban Block Initiatives Influencing Energy Consumption and Solar Energy Absorption

Population growth and urbanization cause developing-country cities to create energy-intensive buildings. Building energy efficiency can be improved through active and passive solar design to reduce energy consumption, increase equipment efficiency, and utilize renewable energy, converting renewable energy into thermal energy or electricity. In this study, passive architecture was evaluated for both urban block and building energy usage. When reliable information and analysis of signs and parameters impacting energy consumption are available, designers and architects can evaluate and passively design a building with higher precision and an accurate picture of its energy consumption in the early stages of the design process. This article compares the location of Baku’s building mass to six climate-related scenarios. Three methodologies are used to determine how much solar energy the models utilize and the difference between annual heating and cooling energy consumption. The structure’s rotation has little effect on the energy utilized in most forms. Only east-west linear designs employ 6 to 4 kWh/m2 of area and are common. Most important is the building’s increased energy consumption, which can take several forms. The building’s westward rotation may be its most important feature. Any westward revolution requires more energy. Building collections together offers many benefits, including the attention designers and investors provide to all places. Having an integrated collection and a sense of community affects inhabitants’ later connections. Dictionary and encyclopedia entries include typology discoveries. These findings will inform future research and investigations. An architect must know a variety of qualities and organizations to define and segregate the environment because architecture relies heavily on the environment. This research involves analyzing the current situation to gain knowledge for future estimations. The present will determine the future.

Implementation of phase change material for cooling load reduction: a case study for Cairo, Egypt

Integrating a phase change material (PCM) into building envelopes can reduce energy needs in the built environment, and the consequent greenhouse emissions. This research examines the impact of PCM integrated into a traditional wall in Egypt on peak and average cooling energy consumption. A MATLAB code based on the finite volume technique using the Crank-Nicolson method for discretization is implemented. Several benchmark cases and experimental results validate the code. The time-dependent boundary conditions of the cases examined were based on the irradiance and ambient temperatures measured in Cairo, Egypt. Simulations are performed on eight different PCMs, using their real published DSC curve. The study aims to investigate the performance of each PCM at different positions, thicknesses, and wall orientations. The calculations revealed that using the proper PCM type and the proper position could decrease the average by 38.14%, Also the peak heat flux could be decreased by 58.53%.

Comparative Study on Performance of Wind-Catcher Shading Device and Other Types of Shading Device on Residential Houses in Tropics

The optimal shading system plays a significant role in a sustainable environment in controlling the amount of excessive sunlight and reducing the thermal discomfort of occupants. External shading device requires many design considerations such as solar altitude, control strategies, and aesthetics to control solar gain, improve the visual environment and reduce glare. Proper external shading design can reduce cooling energy consumption and prevent an overheated indoor environment. This paper focuses on the performance of the Wind-Catcher shading device on the residential house in a hot and humid climate. This study focused on the effect of using Wind-Catcher shading devices on indoor thermal comfort. It proposes solar shading and wind catching design and its performance compared to other types of external shading devices. One of the residential houses in a hot and humid climate is taken as the representative study house of the research. The theoretical and analytical approach will analyze three types of shading devices, such as overhang, box-type shading devices, and wind-catcher shading devices, to validate and compare the shading magnitude amount. The result indicates that the Wind-Catcher shading significantly reduces thermal discomfort hours and allows moderate wind flow into the room rather than other shading types.

Empirical Analysis of the Effects of Window Remodeling using the Slim Double-Skin Window on the Thermal Performance of Old Buildings

Building energy consumption accounts for 30% of the total global energy consumption and is increasing every year. Improvement in the heat transfer performance of the building envelope to reduce energy consumption is a current research hotspot. In the present study, we investigated the performance of the slim double-skin window (SDSW) via empirical analysis. The effect of SDSW-based window remodeling on the thermal characteristics of an old building was investigated with a life-size building. Empirical analysis compared the changes in thermal characteristics between the conventional windows in the old building and the remodeled SDSW. Glass and frame temperature, envelope airtightness, indoor heating environment, and cooling energy consumption were measured before and after window remodeling, and the extent of the influence of external environmental factors, such as insolation, outdoor temperature, and wind speed, on these properties was compared and analyzed. The results show that compared with conventional windows, the SDSWs were less affected by external environment-associated factors, such as sunlight and temperature, thereby maintaining a more comfortable indoor heating environment. Furthermore, the annual building energy consumption was reduced by 34.2% with the use of SDSWs, compared with that of conventional windows.

Dynamic modeling and optimization of organic Rankine cycle in the waste heat recovery of the hydraulic system

The replacement of cooling system with the organic Rankine cycle could reduce cooling energy consumption and improve the overall energy efficiency in the hydraulic system. However, dynamic characteristics have a significant impact on stable operating and performance improvement of ORC systems in applications. Therefore, based on the physical prototype, the ORC dynamic model with whole process, including start-stop process, was established and calibration. Then the dynamic characteristics of the system were studied, and the response surface method was used to optimize the operating parameters with the dynamic model. The results show that the simulation model has sufficient accuracy under both steady and transient conditions. Compared with the oil flowrate, the connected-load affects the system performance more obvious. The evaporating pressure has increased by 3.4% as the connected-load increases from 60 W to 120 W. As to the response time of evaporating pressure and evaporator outlet temperature, they are 240 s and 290 s respectively in the starting stage, and are 210 s and 190 s respectively in the stopping stage. Through the optimization, the output power of the ORC system could reach the maximum value of 832 W, when the working medium pump and expander speed are 1500 rpm and 1400 rpm, respectively. The dynamic fluctuation of oil flowrate has relatively little influence on ORC system, it can work stably in the waste heat recovery of hydraulic system, and the operation and control should consider the long response time of ORC starting and stopping process.

Effect of blind angles on thermal decay in the UFAD system in summer

• Thermal decay depending on blind angle examined two heat transfer effects. • The effect of change in conduction at the bottom surface of the concrete slab on the rate of convective heat transfer. • The effect of change in solar radiation at the top surface of the raised floor on convective heat transfer at its bottom surface. • Optimization of the UFAD system based on analysis of thermal decay and chiller energy consumption, and their dependence on Phi. The objective of this study was to explain and quantify the effect of blinds on the heat transfer paths causing thermal decay and the resulting effects on diffuser discharge temperatures, temperature profiles, supply airflow rate, and energy consumption. To analyze the direct effects of convective heat transfer on thermal decay as blind angle changes, two processes must be examined. The first is the effect of the return temperature on convective heat transfer during operating hours, and the resulting change in conduction rate at the bottom surface of the concrete slab. The second is the effect of change in solar radiation at the top surface of the raised floor on convective heat transfer from its bottom surface, which affects thermal decay. This paper performed an analysis of thermal decay and cooling energy consumption according to the blind angle through a comparison of experimental data and simulation results. Phi means stratification in the room; lower values mean more stratification, which should be considered as a UFAD systems design. The most notable result of this study is the return temperature. It can be seen that during better temperature stratifications, the return temperature was higher due to the plume phenomenon. Although blinds decrease the total indoor cooling load with their shielding effect on the solar radiation load, the rise in return temperature increased the cooling coil load of the air conditioner and the heat storage in the concrete slab. This study will help to understand the relationship between the blind angle, the thermal stratification, and cooling energy usage in the UFAD systems.

Data-driven performance analysis of a residential building applying artificial neural network (ANN) and multi-objective genetic algorithm (GA)

Residential buildings account for nearly 60% of electrical energy consumption in hot climates as in Kuwait. As a result, this study proposes a reliable multi-objective model to obtain the optimal design for a typical residential Kuwaiti building by integrating an Artificial Neural Network (ANN) model with Genetic Algorithm (GA) optimization method. The ANN model was investigated and verified using the results of building performance simulations applying EnergyPlus software. The effects of sample size of dataset on performance of ANN were evaluated. The final optimal building design was optimized using the GA method after ensuring the convergence of the final ANN model. Several design and operation parameters were considered as decision variables, while cooling energy consumption, discomfort hours, and equivalent carbon emissions were selected as objective functions. In addition, sensitivity analysis was conducted to evaluate the impacts of decision variables on objective functions. The sensitivity results indicated that insulation highly affect energy consumption and carbon emission, while cooling setpoint played a key role in discomfort hours. Furthermore, Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method was applied for decision-making among Pareto optimal solutions. The results showed that the optimal solution suggested by TOPSIS methods using ANN-based model provided a substantial reduction in energy consumption, discomfort hours, and carbon emission up to 39.3%, 62.8%, and 40.5% compared with the base case, respectively. It is recommended that further research be undertaken in considering uncertainty parameters on optimization process and applying the developed framework for building in different climate.

Building cooling energy consumption prediction with a hybrid simulation Approach: Generalization beyond the training range

Greenhouse gas emissions associated with energy consumption in buildings contribute significantly to climate change. In subtropical regions, a well-designed building envelope can effectively reduce the energy demand for space cooling. This study proposes a hybrid simulation approach that can be applied to diverse building types to estimate the annual cooling energy consumption. The proposed model, which is based on Bayesian regularization, demonstrates good generalization ability to predict energy consumption for residential as well as healthcare buildings. In the study, a genetic algorithm was employed to optimize the model parameters for obtaining the minimum or maximum envelope heat gain. It is recommended through this study that by adopting a combination, namely, (i) design parameters resulting in minimum envelope heat gain, (ii) coupling of an air change rate of 9 h−1 and recirculation ratio of 50 %, (iii) lowering lighting power density from 13 W/m2 to 7.3 W/m2, would prove to be an efficient strategy that balances energy and infection control for a general inpatient ward. The proposed generalized hybrid simulation approach can be a helpful tool for building systems engineers to formulate design guidelines or renovation plans to reduce energy consumption and thus greenhouse gas emissions.

Thermal and energy benefits of rooftop photovoltaic panels in a semi-arid city during an extreme heatwave event

Rooftop photovoltaic panels (RPVPs) implementation is one of the effective strategies to mitigate urban heat island and relieve urban energy demand with renewable energy resources, which is in need, especially during extreme heatwave events. However, the effects of RPVPs on cooling the urban thermal environment and saving energy have not been fully investigated in terms of RPVPs coverage (CV) and conversion efficiency (CE). To address this question, this study conducted a numerical evaluation of RPVPs on the thermal environment, cooling energy consumption (EC) in buildings, and electricity production (EP) during an extreme heatwave event in a semi-arid Chinese city using the WRF model coupled with building effects parameterization and building energy model. Simulations of twelve scenarios with four CVs and three CEs were conducted. The results indicated that RPVPs implementation could generally lower the 2-m air temperature, due to RPVPs’ higher effective albedo and higher emissivity. An increase in RPVPs CV and CE resulted in stronger cooling effects and larger cooling areas, where the RPVPs with a CV of 100 % and a CE of 0.3 could lower the 2-m air temperature by 0.4 – 0.7 °C, and significantly contributed to a decrease of cooling EC by 14.74 %. The EP could offset and even exceed the cooling EC, with the EP/EC reaching 182.61 %, 135.77 %, and 123.37 % in 100 % coverage (CE = 0.3), 75 % coverage (CE = 0.3) and 100 % coverage (CE = 0.2) scenarios, respectively, indicating that RPVPs could potentially generate enough electricity to compensate cooling EC in semi-arid cities. Our findings have practical implications for the RPVPs implementation and the necessity of improving conversion efficiency for better thermal and energy benefits.

Peak cooling load shift capability of a thermal energy storage system integrated with an active insulation system in US climate zones

This study aims to evaluate a thermal energy storage (TES) system integrated with an active insulation system (AIS) to form a TES + AIS integrated wall system as a partition and as a secondary cooling system to shift the peak load and reduce cooling energy consumption. To understand and demonstrate its cooling performance, the TES + AIS integrated wall system was installed in an office building in Oak Ridge, Tennessee. To investigate the effect of the TES + AIS integrated wall system in a typical office building and various climate zones, the US Department of Energy’s prototype office building model was modified to accommodate the proposed system. Results showed that the minimum size of the proposed system to achieve energy savings varies depending on climate conditions. The minimum size of the proposed system for cooling energy saving and shifting peak cooling demand in climate zones 2, 3, and 5 is 29.7 m2, whereas it is 44.6 m2 in zones 4 and 6. By installing the minimum size of the proposed system, 11.3 % to 16.4 % of cooling energy can be shifted during discharge hours in a representative summer day.

Investigation of VRF system cooling operation and performance in residential buildings based on large-scale dataset

With the increase in the energy consumption of air-conditioning (AC) systems in Chinese residential buildings, the realization of energy savings in AC systems has attracted increasing attention. The variable refrigerant flow (VRF) system is a common AC system for residential buildings in China. In most previous studies on VRF systems, onsite measurements or surveys were conducted to collect operational data. These traditional methods may face various data issues, such as limited sample sizes and invalid data, making them unable to capture the spatial and temporal performance features of VRF systems in residential buildings on a large scale. To fill this gap, with advances in data storage and transmission technology, Big Data methods have been widely used for data collection. In the present study, researchers adopted 16,985 sets of VRF system operation data from China as the database and conducted data analysis for both the spatial and temporal dimensions. Several key indicators were proposed from the two perspectives (spatial and temporal), including the part-space index (PSI), load ratio (LR), use duration (UD), and cooling energy consumption. The main findings were as follows: (1) The “part-time part-space” operation mode of residential VRF systems can be analyzed according to the statistical results of the UD and PSI. (2) An LR of <30% is the main operating condition for VRF systems in residential buildings. (3) Extracted typical LR patterns can reflect different user behavior. The statistical results obtained in this study provide a basis for VRF engineering projects.

Temporal Segmentation for the Estimation and Benchmarking of Heating and Cooling Energy in Commercial Buildings in Seoul, South Korea

The building sector is responsible for more than one-third of total global energy consumption; hence, increasingly efficient energy use in this sector will contribute to achieving carbon neutrality. Most existing building-energy-benchmarking methods evaluate building energy performance based on total energy use intensity; however, energy usage in buildings varies with the seasons, and as such, this approach renders the evaluation of cooling and heating energy difficult. In this study, an information gain-based temporal segmentation (IGTS) method was used to identify the seasonal transition times based on patterns of hourly weather and corresponding building energy use. Twelve commercial buildings were considered for the study and four seasons were identified using IGTS; base-load, cooling energy, and heating energy data were gathered. For the 12 buildings, the estimated and measured heating and cooling energy during the summer and winter periods showed a linear relationship (R2 = 0.976), and the average of those differences was 9.07 kWh/m2. In addition, differences in the benchmarking results based on these energies were marginal. The results indicated that the IGTS approach can be effectively used for determining the actual heating and cooling energy consumption in buildings, as well as for energy benchmarking. This can, in turn, improve building energy use, with positive implications for achieving carbon neutrality.

Energy performance of buildings with composite phase-change material wallboards in different climatic zones of China

The incorporation of phase-change material (PCM) into construction materials has been proposed to indirectly accomplish indoor thermal comfort and energy saving. To adapt to seasonal changes (e.g., hot summer and cold winter), a novel type of hybrid PCM-containing wallboard (including three different PCMs) was proposed with a wide phase-change temperature range and that can work in various climates. In this study, a small building equipped with a hybrid PCM wallboard was established to evaluate energy-saving performance using EnergyPlus. To compare different hybrid PCM wallboards, four building models were considered, including Mode 1, Mode 2, Mode 3, and gypsum wallboard (BASE). The building performance in terms of heating and cooling energy consumption over one year was investigated at seven locations in China to represent different climate zones. The results show that less heating and cooling energy was required for Mode 2 than for the other models. Further investigation of the Mode 2 PCM wallboard revealed that the location of the PCM layer also influenced the energy savings. The total energy requirements for Mode 2 were lower than those for BASE by 2.15%, 4.33 %, 1.77 %, 5.56 %, 7.65 %, 5.84 %, and 0.2% for Shanghai, Beijing, Kunming, Lanzhou, Xining, Harbin, and Hong Kong, respectively. We conclude that the hybrid PCM wallboard can effectively reduce the heat gain through the building envelope throughout the year, presenting a considerable advantage of using it in buildings located in Shanghai, which experiences a hot summer and cold winter.

Combining photovoltaic double-glazing curtain wall cooling and supply air reheating of an air-conditioning system: Energy-saving potential investigation

To address the problems of PV facade overheating and air-conditioning cold-heat offset, this study proposed a novel PV double-glazing ventilated curtain wall system (PV-DVF) that combined PV cooling and dew-point air reheating. A case study was conducted based on an office building with a south-facing PV-DVF in Hefei, compared to one with a conventional PV double-glazing insulated curtain wall system (PV-DIF). This study mainly includes mathematical modeling and validation, performance prediction, and parametric analysis. During a typical summer week, the results reveal that the PV-DVF system achieved (1) a 4.64 °C drop in PV temperature and a 3.4 W (1.07 %) increase in power output, with 7.10 % electrical efficiency; (2) a 2083.22 W reduction in cooling energy consumption; (3) a 4431.81 W reduction in reheat energy; and (4) total electricity savings of 27.92 kWh/day. In the summer, the total electricity savings reached 1566.33 kWh, with an energy-saving ratio of 27.51 %. Furthermore, parametric study results show that properly increasing channel thickness and PV coverage ratio achieves better energy-efficient performance.

The optimization of louvers shading devices and room orientation under three different sky conditions

This paper presents parametric and multi-objective optimization (MOO) approach in optimizing daylight and energy consumption by incorporating louvres shading devices depicting three different sky conditions: Birmingham, UK, Jakarta, Indonesia, and Sydney, Australia. The study aims to observe the best louvre design configuration for each given context. The proposed optimization system iterates the logic of the louvre shading device as the dynamic design parameters such as overhang, blade size, spacing, and blade rotation, together with the room orientation to achieve maximum useful daylight illuminance (UDI) and the shading aperture while simultaneously reduces energy consumption. A total of 8509 simulations for three cities have been run and distributed for the purpose of this research. The results of MOO stated an improvement in UDI for Birmingham, Jakarta, and Sydney of 80%, 146.26%, and 79.48%, and cooling energy consumption of 28%, 3.26%, and 2.99% respectively.

Performance Evaluation of a Water-Circulating Tomato Root-Zone Substrate-Cooling System Using a Chiller and Its Effect on Tomato Vegetative Growth in Chinese Solar Greenhouse

A high-temperature environment is one of the most important factors limiting the growth of crops in Chinese solar greenhouses during summer. To reduce the substrate temperature of summer plant cultivation in a Chinese solar greenhouse, we proposed a water-circulating tomato-root zone-substrate-cooling system (WCTRZSCS). The system used water as the circulating medium, a chiller as the cooling source, and polyethylene raised temperature resistance (PE-RT) pipes laid in the substrate as the cooling component. The greenhouse was divided into test area TS1 (one PE-RT pipe), TS2 (two PE-RT pipes), and a control area CK (no PE-RT pipe) for the root-zone substrate-cooling test. The results demonstrated that (1) in the summer, WCTRZSCS can effectively reduce the substrate temperature, and (2) WCTRZSCS improves the temperature conditions for tomato vegetative growth. There were significant differences in plant height, stem diameter, dry weight, fresh weight, leaf area, net photosynthetic rate, total root length, and total root projection area between tomatoes in the test and control areas (p &lt; 0.05). The TS1 and TS2 growth rates were 60.2% and 81.2% higher than CK, respectively, and the light-utilization efficiency was 56.3% and 81.3% higher than CK. (3) The system’s cooling energy consumption per unit ground area was 35.2~67.5 W·m−2, and the coefficient of performance (COP) was 5.3~8.7. Hence, WCTRZSCS can effectively reduce the substrate temperature in the root zone, but the profit by tomato cannot offset the cost of using WCTRZSCS. Through the optimization of and improvement in the system, its economy may be further improved, and it is expected to be applied in practical production.

An Assessment of External Wall Retrofitting Strategies Using GRC Materials in Hot Desert Regions

Due to urbanization, population growth, and the consequences of climate change, the usage of energy for cooling has increased considerably in recent years. Passive climate measures, on the other hand, could alleviate the situation by reducing energy use in buildings. This study examined the environmental and financial benefits of utilizing glass fiber-reinforced cement in the external walls of a communal social hub building in New Aswan city, taken an example of the hot desert region. Utilizing Design Builder software, the effect of various outside wall alternatives on cooling energy consumption was explored and analyzed. In addition, a cost–benefit analysis utilizing the simple payback period was conducted to aid decision-makers in selecting the most suitable exterior wall materials for public buildings in hot desert regions. Using cement plaster, cement brick, glass wool, and glass fiber-reinforced cement as an outside wall resulted in a significant improvement rate, according to the data. Compared to a typical wall (cement plaster, cement brick, and cement plaster), it can save up to 41% of energy. In addition, it has the lowest simple payback period value when compared to other examined solutions (10.86 years). In general, the results indicate that glass fiber-reinforced cement walls embedded in thermal insulation materials and incorporated into cement brick walls are more energy-efficient in terms of necessary cooling energy and economic viability.

Le Corbusier’s Solar Shading Strategy for Tropical Environment: A Sustainable Approach

In warm and tropical climates, excess solar gain may result in high cooling energy consumption. Shadingis a simple method to block the sun before it can get into the building. The ‘brise-soleil’, or ‘sun-breaker’solution refers to a permanent sun shading technique, like the simple patterned concrete walls popularized byLe Corbusier. Le Corbusier in his design of buildings in tropical climate wanted to make a ‘pact with nature’unlike his earlier works of the cold climates where he was to ‘combat the nature’. Le Corbusier’s solar shadingstrategy in Unit De Habitation and Capitol complex in Chandigarh are pioneering example for his approachtowards dealing with the harsh tropical climate. This paper tries to rediscover the climate consciousness ofthe master architect in terms of Brise Soleil as his solar shading strategy for the tropical environment. Themethodology adopted in the research is through qualitative analysis. In this paper an attempt has been madeto analyse Brise soleil as a solar shading strategy with reference to the tropical architecture of Le Corbusier.The application of Brise Soleil in Le Corbusier’s tropical works such as Ministry of education in Rio de Janeiro,Unité d’ Habitation in Marseilles and Capitol Complex in Chandigarh has been studied. The relevance ofshading in today’s context with reference to climatic control and energy conservation and sustainability hasalso been discussed. Incorporation of Brise Soleil as a solar shading technique in buildings will certainlyreduce our dependency on artificial means for thermal comfort and minimize the environmental problems dueto excessive consumption of energy and will evolve a built form, which will be more climate responsive andmore sustainable.