Search

This paper investigates the simultaneous effect of orientation and thermal insulation of the building on each other and on the heating and cooling loads of buildings. For this aim, the heating and cooling loads of a sample building are calculated with different orientations and amounts of thermal insulation in multiple cities in Iran, which have different climatic conditions. The optimum building orientation in all the surveyed cities is when the main façade faces south, which can reduce the energy consumption of the building by 11–39%. This reduction was greater in cities with higher cooling-degree-days (CDD); which means the effect of orientation on the cooling load of a building is more significant than its effect on the heating load. Increasing the thermal insulation of the exterior walls also reduced the energy consumption of the building. 5–10% reduction in total energy consumption of the building was observed by decreasing the u-value of external walls from 0.8 to 0.4 W/m2K. This reduction was higher in cities with higher heating-degree-days (HDD) which means that the effect of insulation on heating energy consumption is more significant than its effect on cooling energy consumption. In addition, the results indicate that the building orientation and thermal insulation improve each other's efficiency. Highlights The effect of building orientation on energy consumption was investigated. Building envelope insulation effect on heating and cooling demands was investigated. The simultaneous effect of building orientation and insulation was analyzed. The results were discussed concerning different climates and climatic conditions. [ABSTRACT FROM AUTHOR]

This paper aims to create an experimental building structure using 3D printing technology to reduce the interior temperature. Because of its sensitivity to high temperatures, particularly its low heat deflection temperature, and susceptibility to deterioration over time, the Polylactic acid (PLA) material has been preferred to print the layer. In this model, an effort was made to decrease the building's overall cooling load, which may result in a higher amount of ordinary power being required. For the study, a new model of the intended wall was developed and tested. The studies were carried out in two modes: the first without any PCM in the wall, and the second with an additional new model of PCM 3D-printing layer within the wall. The test results demonstrated that the PCM 3D-printing layer inside the wall building lowered the temperature of the outer wall surface, the inner wall surface, and subsequently the building temperature of the indoor area to a huge amount. The achievements are in the percentage peak temperature reduction of 9.8% for the wall's outer surface, 22.6% of the inner wall surface, and 13.4% of the room temperature. With the help of the PCM 3D-printing layer, the peak indoor temperature was decreased by 5℃. [ABSTRACT FROM AUTHOR]

As hot days are getting hotter and more frequent, urban dwelling is expected to increase cooling energy use in current and future climate. The applicability of dynamic building simulation in estimating cooling loads of a city's housing stock can be limited due to lack of fine-grained on-site current and future weather inputs. For predicative modelling of residential cooling energy demand to aid a city's energy supply planning resilient to excessive heat conditions, it requires cooling energy demand projection based on a relational account of (1) the thermal-environmental interaction between housing stocks and urban microclimate conditions, (2) the city dwellers' cooling energy use behaviour, and (3) the city's climate projections. In this paper, we introduce an 'archetype-in-neighbourhood' framework to meet these requirements. Combining empirical urban data modelling and EngeryPlus model calibration, this framework was developed to obtain statistically a maximal cooling energy demand model of a city's housing stock during yearly hottest periods. We applied the framework to multiple datasets selected from Seoul's open urban data sources for the period of 2014–2017 (2014 being the earliest year of data availability, 2017 being the end of the study period), including metered electricity use data of 659 apartment buildings (51,351 households) sampled from 18 city districts. The results show that maximal month cooling energy demand (MMCD, kWh/m2) of Seoul's housing stock can be expressed as a regression function of two determinants: (1) the city's average outdoor temperature during the hottest month period (T ex , °C), and (2) estimated indoor cooling temperature set-point (T in , °C) of the city' housing stock during the same period. Through a k -fold (k = 4) validation, the current regression model (2014–17) was evaluated to have an overall coefficient of determination R2 =0.969. Assuming no housing stock renovation, we applied the model to generate scenarios of maximal month cooling demand in future years according to some of the highest summer temperatures projected for Seoul (RCP8.5 2045, RCP4.5 2047, MM5 2071–2100). We conclude this paper with a brief discussion of the implication for cooling energy supply planning and further work to extend the applicability of this new framework to housing stock adaptation planning and design. [ABSTRACT FROM AUTHOR]

• The harvesting related to the electrical energy production of a BIPV as a shading device and roof top photovoltaic (PV) system was simulated by "SolCel (Ver.2019)" which can consider also an influences of obstacles against a reflected irradiance around a BIPV and evaluate a thermal comfort characteristic of an adjacent room, and a solar irradiance for bifacial PV module, etc. • And this paper describes the ecological criteria to optimize the solar architecture through an ecological convergence of a passive solar architecture and photovoltaic system and newly suggested simulation model for solar architecture, considering results from a remodeling process of a small or medium-sized public building by an ecological application of the photovoltaic system. The solar architecture is defined as a kind of building integrated photovoltaic (BIPV) which the Photovoltaic (PV) modules are deployed to passive solar concepts, to minimize the heating & cooling load, to upgrade the indoor environmental quality and to be adjustable for regional weather and to continuously succeed architectural culture and history. The most ideal form of a BIPV is a multi-functional and ecological convergence through a passive concept application of a photovoltaic module for a building. The solar architecture needs to consider the architectural culture and history of the region through an ecological convergence which is applicable to a passive concept if the environment, energy and comfort problems will be effectively mitigated. The evaluation standard is needed to fulfill these requirements of solar architecture. The renewable energy sources are getting very hot issues, due to the environmental pollution, global warming, and energy shortage, etc. It is reasonable to disseminate the representative energy systems which could be ecologically convergent with the regional architecture. Most renewable energy systems including PV could not be activate or not be environmentally friendly if the systems are planned simply without multi-functional and ecological convergence. This paper describes the ecological criteria to optimize solar architecture through an ecological convergence of a passive solar architecture and photovoltaic system. [ABSTRACT FROM AUTHOR]

Summary: Ice thermal energy storage (ITES) is a significant option for shifting cooling load from peak hours to off‐peak hours in order to reduce the cooling cost and equipment capacity. Encapsulated ITES system is one of the most preferred types of ITES systems, because it is easier to apply and has lower initial cost than other types of ITES systems. Capsule geometries have great impact on the thermal performance of the encapsulated ITES system. Spherical capsules are widely used in the application because they provide better thermal performance due to the ratio of its volume to its surface area. Also, modified capsule geometries are used for increasing the thermal performance of the ITES system. This paper focuses on a numerical study in order to determine the effect of the geometrically modified spherical capsule on the thermal performance during the discharging period. Seven geometrically modified spherical capsules were investigated and compared with the ordinary spherical capsule. The FLUENT 17.1 code was used for numerical analyses. At the end of the study, it was found that geometrically modified capsules provided higher thermal performance than an ordinary spherical capsule in the equal capsule volume. Capsule D provided the longest discharging period of 2118 seconds, when VHTF, in = 0.001 m/s and THTF,in = 275.5 K. The lowest discharging time of 464 seconds was obtained with Capsule A, when VHTF, in = 0.01 m/s and THTF, in = 283 K. Among the studied modified capsules, Capsule F performed the worst thermal performance. Energy efficiency values were high, and they did not give comparable difference between the capsule models and working conditions. While all exergy values were 98.50% and higher, exergy efficiency values changed between 85.12% and 51.91%. Exergetically, Capsule D provided the best thermal performance during the discharging period. [ABSTRACT FROM AUTHOR]

The use of an underfloor air distribution (UFAD) system integrated with a chilled ceiling (CC) cooling system can provide a potentially advanced heating, ventilation, and air conditioning (HVAC) system with high sensible cooling loads in modern office buildings. In this paper, an experimental study of the impact of CC in a room with a high sensible cooling load with UFAD was performed when the chilled ceiling surface temperature increased from 17.0 to 26.0 °C. The vertical distributions of indoor air temperature, air velocity, and pollutant (CO2) concentration were measured and evaluated by the vertical air temperature difference (VATD), turbulence intensity (TI), and contaminant removal effectiveness (CRE), respectively. The results showed that the average VATD, TI, and CRE were 0.1–0.9 °C, 4–40%, and 0.85–1.19, respectively, when the internal and external sensible cooling loads equal 41.5W/m2. These evaluation indices varied clearly when the internal sensible cooling load increased from 41.5 to 69.5W/m2, whereas they were almost the same when the external sensible cooling load increased from 41.5 to 69.5W/m2. The minimum CRE and air diffusion performance index (ADPI) coincided with the maximum heat removal effectiveness (HRE) under a constant cooling load condition. The results suggest that it is better to balance the energy consumption as well as indoor air quality and thermal comfort in a room with UFAD + CC. [ABSTRACT FROM AUTHOR]

Heat buildup is an important issue on the cutting edge which then promotes high-temperature wear which consequently leads to poor machinability during dry machining. To improve the machinability, new tool holder designs accommodating cooling techniques have paid considerable attention toward the manufacturing domain recently. Whereas, in this paper, a new tool holder is designed and fabricated to serve for multipurpose cooling arrangements (internal cooling, external cooling) to reduce the heat buildup of the cutting edge along with the consolidated air system to clear away the chips. Initially, need of new tool holder is discussed followed by its manufacturability and machinability characteristics to a machine for nickel alloy Inconel 725. Machinability studies then are compared for dry machining, internal and external wet machining, and tool wear results are discussed. Thus, improvement in tool wear of around 70-75% and 65-72% is observed for internal wet, external wet concerning dry machining, respectively. Whereas, 15-18% (flank wear) and 6-9% (nose wear) improvement are seen for internal wet machining when compared with external wet machining. Results are best understood for internal cooling using a new tool holder. [ABSTRACT FROM AUTHOR]

This paper presents a novel framework for economic cooling load dispatch in conventional water-cooled chillers. Moreover, information gap decision theory (IGDT) is applied to the optimal chiller loading (OCL) problem to find the optimum operating point of the test system in three decision-making modes: (a) risk-neutral approach, (b) risk-aversion or robustness approach, and (c) risk-taker or opportunistic approach. In the robustness mode of the IGDT-based OCL problem, the system operator enters a desired energy cost value in order to find the most appropriate loading points for the chillers so that the total electricity procurement cost over the study horizon is smaller than or equal to this critical value. Meanwhile, the cooling load increase is maximized to the highest possible level to find the most robust performance of the benchmark grid with respect to the overestimated load. Similarly, the risk-taker optimization method finds the on/off status and the partial load ratio (PLR) of the chillers in order to keep the total energy cost as low as the given cost function. In addition, the minimum value of cooling load decrease can be found while satisfying the refrigeration capacity of the chiller and the load-generation balance constraint. Thus, a mixed-integer non-linear programming problem is solved using the branch and reduce optimization (BARON) tool of the generalized algebraic mathematical modeling system (GAMS) for a five-chiller plant, to demonstrate that IGDT is able to find a good solution in robustness/risk-taker OCL problem. [ABSTRACT FROM AUTHOR]

A large amount of wind turbine power and photovoltaic power is abandoned in many areas with abundant renewable energy due to thermal-electric coupling, inadequate local consumption capacity, and limited capacity of transmission lines, etc. To solve the above problems, a coordinated dispatching method for integrated energy systems is proposed in this paper. Firstly, the spatiotemporal characteristics of diversified loads in multiple functional areas are introduced, including the inertia and elasticity of heating/cooling loads, the spatiotemporal distribution of electric vehicles, and the optimum transmission distance of diversified loads, etc. Secondly, a coordinated dispatching model of integrated energy systems is proposed, which considers the differences of multiple functional areas and various forms of energy systems. Finally, an actual distribution system in Jianshan District, Haining, Zhejiang Province of China is investigated for demonstrating the effectiveness of the proposed model. The results illustrate that the proposed model could effectively improve the consumption rate of renewable energy and reduce the volatility of renewable energy by considering the coordination of electric vehicles, tie lines, and heating/cooling systems in multiple functional areas. [ABSTRACT FROM AUTHOR]

Abstract Neighbourhood form imposes complex effects on the local microclimate. The overlook of neighbourhood microclimate will lead to miscalculation of building energy performance. In this paper, a neighbourhood-scale building simulation coupled between building energy simulation and CFD is proposed to assess the impact of external convective heat transfer coefficient (CHTC) to the building thermal performance. The co-simulation is run for different types of buildings inside the neighbourhood with different combinations of neighbourhood form parameters. The developed simulation scheme allows the iterations of neighbourhood design parameters and simulation model generation in CFD and EnergyPlus. Five empirical methods are used to predict CHTC, and the results of CHTC values, heating and cooling load intensity are compared in detail with the proposed CFD coupled method. The results suggest that the orientation and multiplier are crucial to the building load intensity in Chicago and the neighbourhood form can affect the thermal load of residential building up to about +27.1% and −18.6%, and +17.2% and −7.7% for office buildings. The proposed method and framework in this paper is capable of generating design guidelines for the optimal energy performance of the buildings in the neighbourhood. Highlights • Neighbourhood-scale building block energy simulation coupled with CFD. • Iterated various neighbourhood design parameters and building model generation. • Empirical methods in evaluating CHTCs are evaluated and compared with CFD method. • Neighbourhood form can affect certain type of building's energy use up to ± 20%. • Neighbourhood design guideline for optimal building thermal load is suggested. [ABSTRACT FROM AUTHOR]

Night ventilation has great energy saving potentials for public buildings in summer. However, night mechanical ventilation inevitably causes more fan energy consumptions, even though it can reduce the cooling loads for the next day and save the air conditioning energy consumption correspondingly. Thus the optimization of night mechanical ventilation strategy is highly significant for building energy efficiency. In this paper, the simplified two-plate room model is used and the optimization model of the mechanical ventilation and air conditioning system is established. To minimize the total energy consumption, the optimal night ventilation strategy is determined through inverse problem method. Taking an office room in Beijing as the illustrative example, the results show that the optimal air exchange rate for night mechanical ventilation is much higher than the traditional value (ACH = 0.5 h−1) and it highly depends on the indoor-outdoor air temperature difference and cooling load demands. Moreover, the total electricity usage amount can decline from 210 kWh to 111 kWh after optimization, reduced by about 47% in the whole summer season. It also indicates that the energy saving effect of night ventilation mainly derives from the cooling storage and load shifting of building internal walls. Compared to traditional ventilation strategy, the energy saving ratio increases with increasing thermal conductivity and specific heat of building internal walls. This work can provide guidance for practical ventilation system optimization design and operation strategy determination. [ABSTRACT FROM AUTHOR]

Dynamic cooling and heating load forecasting of heating, ventilation and air conditioning (HVAC) systems is a basis for optimizing the operation of HVAC systems and can contribute to achieving the effective management for the HVAC systems. This paper proposes a load forecasting method for office buildings based on artificial intelligence and regression analysis, including wavelet transform, support vector machines (SVM), and partial least squares regression (PLS). An office building located in Tianjin, China is taken as the building case study to validate the proposed model. For selecting the input variables, the methods of sensitivity analysis and correlation analysis are used. The results of different prediction horizons, mainly including 1 h ahead, 2 h ahead, 3 h ahead and 24 h ahead forecasting, are finally provided. In order to illustrate the accuracy improvement of the proposed model, the other three models are built to compare with the proposed model. Further, the influence of weather forecast precision on the proposed model is analyzed in this paper. The results indicate that the proposed method can realize dynamic load forecasting with high accuracy for different time horizons. [ABSTRACT FROM AUTHOR]

• A comparison method between energy-only and energy and reserve model. • Higher revenue for flexible technologies was achieved for joint model. • The down reserve proved to be more required in high RES systems. • The study showed significant difference in operation between two models. The requirements for ancillary services in energy systems are growing as the amount of renewable energy sources such as solar and wind increases. On the other hand, the system can benefit from extra sources of flexibility thanks to the increased digitalization that enables successful integration of demand response and energy storage. The majority of recent energy system analysis research did not consider the regulation markets. As a result, these investigations preclude the ability to fully evaluate the advantages of energy storage and flexible cooling loads. With the method outlined in this paper, it is possible to compare the two strategies and assess the advantages of energy storage and flexible cooling loads for each strategy. In addition to the energy storage systems, the case study in this paper focuses on flexible cooling loads as a significant consumer in the system. According to the findings, the system's operating costs increased by 19.4% when reserve limitations were placed. Furthermore, the findings demonstrated that when flexible assets were permitted to participate in the reserve market, they generated significantly higher incomes. According to the findings, mechanisms that will allow energy storage and demand response to provide reserve capacities as well as the growth of reserve markets are both necessary. [ABSTRACT FROM AUTHOR]

This paper was aimed at studying the impact of a variable speed drive in tackling the issue caused by an oversized air conditioning system. In this study, oversizing was determined by calculating the actual load demand in an operating air handling unit (AHU), and the formation of mould growth as an indicator of the failure of the AHU to dehumidify the air. A comparison was made between the performance of an actual operating AHU, the performance of the AHU after the installation of a variable speed drive (VSD), and an appropriately sized simulated model of a building using building energy simulation software. The study found that the installed AHU was oversized by 60% and that the installation of VSD is effective in reducing the effective total capacity to meet actual cooling load demand. This study also shows that VSD installation successfully eliminates favourable condition of mould growth by simultaneously reducing AHU capacity and room relative humidity. However, VSD installation should not be standard practice in lieu of proper calculations to determine the appropriate size for an air conditioning system. The simulation result shows that correctly sized air conditioning system will be able to maintain ideal room condition without incurring energy penalties associated with oversizing. [ABSTRACT FROM AUTHOR]

• For modeling non-equilibrium condensation, the wet steam multi-phase model is used. • Water is applied in ejector refrigeration cycle as economical and non-toxic fluid. • Effects of droplets injection at secondary flow causes reducing COP and ER. • In special case, the steam accompanies by droplets at the outlet of ejector. • Designers and operators should consider effects of droplets in ejector performance. Steam ejector plays a key role in the refrigeration system. The water has been used as a working fluid because water is more economical and non-toxic. The operating fluid often enters the evaporator as a water liquid and droplets evaporate by absorbing heat. Cooling load changing causes the vapor in the outlet of the evaporator to be accompanied by droplets. Therefore, there are droplets at the inlet of secondary nozzle and flow should be simulated as a wet steam flow with injection droplets at the secondary flow. In this paper, the effects of droplets injection at secondary flow have been investigated on the performance of the refrigeration cycle. For this purpose, the Eulerian-Eulerian method has been used and the results have been validated with experimental data. Six cases are considered with different wetness and number of droplets in the secondary flow. The results of case 6 show COP, T ¯ outlet , and ER decrease about 22.93%, 15.66%, and 22.93%, respectively. In addition, the steam accompanies by droplets at the outlet of ejector. Therefore, it is essential for designers and operators to model and consider the effects of the droplets on the wall erosion to optimize the wet steam ejector and refrigeration cycle performance. [ABSTRACT FROM AUTHOR]

In this paper, numerical simulations of Diffusion Absorption Refrigeration – DAR cycle were conducted in order to study the performance of two configurations in steady state mode and use ammonia, water, hydrogen as working fluids. The two configurations were numerically simulated using models developed with the commercial flow sheet Aspen HYSYS V10 software. The first configuration where the main simple DAR cycle components were simulated and validated the experimental results. The second configuration where the modified DAR cycle was simulated which has an auxiliary heat exchanger added to the main simple DAR cycle as a modification. It was found that for the same input assumptions and heat applied, the modified DAR cycle shows higher cooling load. Therefore, higher COP than the simple DAR cycle. The optimal operation of the modified cycle is 36 W applied to the generator to achieve a COP of 0.235 instead of 0.209 for simple DAR cycle. The Simulation results show that by using the modified cycle, the COP improves by 12.4%. [ABSTRACT FROM AUTHOR]

In this paper, we propose a real-time cooling load forecasting system in order to overcome the problems of the conventional methods. The proposed system is a new load forecasting model that hierarchically combines Support Vector Data Descriptions (SVDDs). The proposed system selects an optimal attribute subset by our cooling load forecasting system that enables real-time load data generation and collection. The system is composed of two layers: The first layer predicts the time slots in three representative forms: morning, midday and afternoon. The second layer performs specialized prediction of each individual time slot. Since the proposed system enables both coarse-and fine-grained forecasting, it can efficient cooling load management. Moreover, even when a new time slot emerges, it can be easily adapted for incremental updating and scaling. The performance of the proposed system is validated via experiments which confirm that the recall and precision measures of the method are satisfactory. [ABSTRACT FROM AUTHOR]

The shape of a building largely contributes to its energy consumption. The current study utilized metrics of surface-to-volume ratio, surface-to-floor ratio, area-to-perimeter ratio, and volume ratio to evaluate building energy performance. Also, the paper focused on the relation between the air-conditioned room and non-air-conditioned room. This approach affects both the design stages of the floor plan and the main designing factors that decide which spaces would become air-conditioned spaces such as those mostly occupied by residents or non-air-conditioned space such as staircases and elevators. The heating load and cooling load were calculated using the new equation based on the location of non-air-conditioned spaces and envelope ratio facing the outdoor. Both the width-depth ratio and envelope ratio were analyzed using the IES_V.E (Integrated Environmental Solutions Virtue Environment) program. It turns out that, as the non-air-conditioned spaces increase, both heating load and cooling load were reduced. [ABSTRACT FROM AUTHOR]

Due to vertically thermal stratification in indoor spaces, the cooling load calculation is always a challenge in the design of stratified air distribution systems (STRAD), which in turn is crucial to determine the supply air flow rate and the cooling load to be removed by the air conditioning system. In this paper, several cooling load calculation methods, developed in the past 20 years and focused on STRAD systems, were briefly reviewed. It attempts to clarify these methods in terms of their advantages, limitations and suitable ranges of applications. Furthermore, series of numerical simulations with a total number of 56 cases were conducted, and the applications of a novel cooling load calculation method in STRAD systems were investigated. The reliability of the method was validated for STRAD systems with separated locations of return and exhaust grilles, when adopted in three typical spaces with different building heights, namely a small office, a large terraced classroom and a terminal building. Databases of effective cooling load factors ( ECLF i ) for different heat sources distributed in the three spaces were obtained and presented, which can be conveniently used to calculate cooling loads. In addition, the influences of return grill height on the occupied zone cooling load as well as the energy saving potentials of STRAD systems were also clarified. The results presented in this paper are helpful for the design and optimization of STRAD systems. [ABSTRACT FROM AUTHOR]

In the long-term operation of a geothermal heat pump system, when the cooling load is high, the temperature rise in the ground due to heat accumulation occurs. Changes in ground temperature hinder recovery of the temperature on the heat source side of the heat pump, and the performance of the geothermal system deteriorates because the heat exchange efficiency of the circulating water decreases. This problem can be solved by operating a hybrid geothermal system composed of an additional heat source system to the geothermal system. Therefore, in this paper, a method for operating a hybrid geothermal heat pump system was proposed to solve the degradation of system performance due to the temperature rise in the ground due to heat accumulation. The operating conditions for starting the operation of the hybrid geothermal heat pump system were derived, and the coefficient of performance prediction model was proposed for flow rate control considering the energy of the pump and the heat pump system. In addition, the proposed control method was evaluated for energy saving and performance improvement through simulation, and was also evaluated in terms of economic feasibility. [ABSTRACT FROM AUTHOR]

With the rapid development of global informatization, data center computing tasks are increasing, and the resulting energy consumption problems are particularly prominent in the context of carbon emission reduction, and affect the safe and green operation of data centers. Aiming at the problem of high and large fluctuation energy load of data center servers, this paper presents a method of optimizing data center servers load considering spatial-temporal load distribution of computing resources. Co-optimized allocation of computing resources and load is studied with examples from the property that computing resources is adjustable in time and space dimensions. The results show that the proposed method is able to reduce the peak electric and cooling loads of the data center room by 10.7 %, reduce the total annual electric consumption by 2.66 % and the total annual cooling consumption by 2.46 %, and reduce the economic and environmental costs of energy supply for the data center in the case study, which comprehensively shows that the load optimization of data center servers has been achieved through the optimal allocation of computing resources. [ABSTRACT FROM AUTHOR]

To reduce building energy consumption and improve indoor air quality, this paper proposes a CdTe PV double-skin ventilated facade integrated with a thermal-catalytic air type PV/T (PV-DSF-TCPV/T). The mathematical model of the proposed system was developed and validated against the experimental data. The daily and seasonal overall performances of the proposed system, including the electrical, thermal, and formaldehyde degradation performances, were studied and compared with that of a conventional PV-DSF. Moreover, parametric analysis was conducted. The main results are: (1) The annual electricity outputs of the proposed system and the conventional system were 414.88 kWh and 105.88 kWh, respectively. (2) Compared with the conventional PV-DSF, the heating and cooling loads of the proposed system decreased by 10.85 % and 34.86 %, respectively, due to the reduction of indoor heat gain in summers and the increase of it in winters. (3) The daily formaldehyde conversion ratio and CADR were 30.84 % and 67.86 m3/h (4) The volumetric flow rate and the cell coverage of the PV-DSF both exerted obvious impacts on the proposed system. • A PV-DSF integrated with the thermal catalytic PV/T was proposed. • Corresponding mathematical models were established and validated. • Daily and seasonal energy performances were investigated and compared. • The impacts of two design parameters were analyzed and discussed. [ABSTRACT FROM AUTHOR]

Cooling load characteristics play a key role to the building, especially in self-sustained building. It is determined mainly by the building envelope thermal performance. This research investigates the effect of the building envelope on cooling load in low latitude and hot-humid area. In this paper, based on cooling load simulations, the effect of reducing the cooling load of building envelope and the life cycle cost was analyzed. In addition, the energy-saving system was established. For the life cycle cost analysis, the cost of each strategy was obtained through a survey in local stores. This paper determining the effect of external walls, windows, roof, shading on the building cooling load, and pointed out the optimum insulation thickness of roof and all orientation exterior wall. And the optimum window structure and exterior shading length was give. [ABSTRACT FROM AUTHOR]

Aisle containment separates hot and cold aisles in air-cooled data centers to prevent hot air recirculation into cold aisle and decrease temperature nonuniformity among the servers. Uniform server inlet temperatures allow the cooling system to operate more efficiently at a higher evaporator temperature. Lower cooling power consumption can be achieved by optimizing the combined power consumption of the chillers and the computer room air handlers (CRAHs) fans. CRAH bypass (BP) is proposed, in which additional fans at the tiles induce a fraction of tile flow from the room into the plenum through low-resistance ports or leakage paths, thus decreasing the airflow passing through the high pressure resistance of the CRAH heat exchangers and filters and associated fan power usage. A further advantage of the proposed induced CRAH BP is the elimination of leakage as a result of reversing the room-plenum pressure difference. However, in order to keep the enclosed-aisle temperature below acceptable limits (typically ≤27 °C), the chiller needs to operate at a lower, less efficient temperature. This paper presents the experimental verification of a flow network model (FNM) in a data center test cell demonstrating the proposed induced CRAH BP concept. Exercise of the verified FNM in conjunction with a thermodynamic model of the cooling infrastructure (TDM) confirms that there is an optimum BP fraction that minimizes the combined chiller and CRAH fan power consumption. [ABSTRACT FROM AUTHOR]

The dynamic heat transfer of building surfaces has thermal conduction, convection and radiation at the same time. It is the basis of building thermal environment simulation, air conditioning load calculation, building energy analysis and air conditioning system conservation operation. Under cyclic heat flow, the convection and radiation separating method was used to calculate the radiation heat and convection heat of building surfaces, and dynamic characteristics of convection heat and radiation heat on building surfaces was provided in this paper. For the dynamic heat transfer of building surfaces under cyclic heat flow, three indexes of peak error, mean error and average relative error were used to analyze dynamic heat transfer. The temperature distribution and dynamic heat transfer of convection heat and radiation heat of building surfaces were studied systematically. The separating cooling load and the room cooling load were basically consistent with each other, the convection and radiation separating method was reliable and available. The peak value of convection heat corresponded to the foot value of the radiation heat, and the relative error of them was 1.9%-2.2%. The dynamic characteristics of radiation heat and convection heat had important reference for the study of dynamic heat transfer of building surfaces under cyclic heat flow. [ABSTRACT FROM AUTHOR]

Rural Research Stations (RRS), Refugee Camps Motorhomes and Caravans are in need of a portable Compact Heating, Cooling and Power (CHCP) generating device. Heating and power generation devices with diesel as driving source of energy are available commercially. In this paper, an innovative compact heating, cooling and power generating device which uses renewable hydrogen and suits rural areas, extreme weather conditions and disastrous situations is proposed. The device is driven by renewable hydrogen fuel generated by PV electrolysis as the source of energy. Low vibration low noise Stirling Engine (SE) is used as mechanical energy converter. Generator is used as electrical energy converter and heat pump is used for supplying heating and cooling effects. The proposed device has many advantages such as encouraging the rural tourism, supply rural research stations the heating and/or cooling loads and contribute in saving lives in the extreme weather conditions and disastrous situations. Analysis of the proposed device in terms of workability and performance was performed. Results showed that renewable energy base, electricity independent, silent, low vibration and better performance were achieved (OHR = 2.662) with the current device compared to available devices. • Generating Hydrogen by PV electrolysis. • Hydrogen Combustion for driving Stirling Engine. • Generation Electricity using Stirling Engine. • Driving Heat Pump for Heating or Cooling. [ABSTRACT FROM AUTHOR]

• An elastocaloric ventilation device is dynamically simulated for building cooling. • An optimized, energy-saving logic is tested, including recirculation and partialization. • Across 8 cities in the world, the device could cover up to 70% of the energy load. • Climate-sensitive design guidelines are provided along with technological constraints. • Terminal velocity, ventilation rate and depth are found to be pivotal design parameters. Refrigerants in vapor-compression systems have a global warming potential thousands of times that of carbon dioxide, yet their spread on the market is unrivalled. Elastocaloric systems, based on solid state cooling, feature among the most promising alternatives. In this paper, an elastocaloric device for air ventilation (ECV) composed by parallel and serial connection of multiple shape memory alloy (SMA) films, is investigated via volume-based finite difference simulation in MATLAB and dynamic building simulation in TRNSYS considering eight cities across the globe. The models assume experimentally demonstrated thermal parameters for the elastocaloric phase transformation around room temperature and a single-storey reference building. The ECV operates according to an optimized, energy-saving logic that includes load partialization and recirculation. Parametric analyses suggest that moderate terminal velocities (∼2 m/s) and a climate-specific design aimed at maximizing the use of the ECV device at nominal cooling capacity are key to reach building cooling needs reductions up to 70% in the considered scenarios. Partialization results in enhanced energy flexibility and conservation, whereas recirculation extends the ECV usability to extreme heat conditions. In absolute terms, the ECV works best under hot climates (e.g. Cairo, Dubai, Brisbane), with monthly cooling load reductions about 2/3-fold compared to cold locations (e.g. Milan, Hobart). The performance is extremely sensitive to the ventilation rate. Thermal zones requiring 1 to 2 air changes per hour are best suited. These findings provide initial insight into design criteria, opportunities and limitations on the use of elastocaloric devices for building ventilation to guide future experimental verification. [ABSTRACT FROM AUTHOR]

A load-based testing methodology has recently been developed for laboratory testing of residential cooling equipment with its integrated controls that employs a model to emulate building dynamics and their interaction with equipment controls. This approach is part of a new performance rating standard that utilizes a bin method to estimate a seasonal energy efficiency (CSA EXP-07, 2019; Cheng et al., 2021). However, a "holy grail" for future equipment performance rating is to be able to map equipment performance using load-based testing results and then implement the map as a "model" in building energy simulations to generate seasonal performance ratings that are specific to various building and climate types. With this goal in mind, this paper presents a performance mapping methodology that incorporates a "gray-box" model structure that uses inputs that are consistent with building energy simulation programs (sensible cooling load and equipment inlet conditions) and outputs key performance metrics (total sensible and latent cooling rates, power consumption, and COP). A strategy and a test matrix for training the model with a relatively small number of testing points were established by developing a successive optimization approach to identify the best 12 test conditions to apply for training from a larger set of available data. In order to develop, demonstrate, and validate the modeling and training approach, load-based laboratory testing was set up within psychrometric chambers and testing was performed to generate 39 quasi-steady-state data points over a range of loads and boundary conditions with a test unit operating with its normal integrated controls. The best model trained using the optimal training subset of 12 data points was able to represent the equipment performance across the operating envelope within ± 10 %. [ABSTRACT FROM AUTHOR]

The paper aims to explore the effect of different passive cooling measures using thermal modelling and predicting. Solar shading, green roofs and cool paints were incorporated as passive cooling measures to evaluate their combined effects on indoor environment, thermal comfort and its importance in energy conservation. A field experiment study was conducted in the sub-Saharan climate of Kiambu, Kenya where microclimate indicators were measured for validating and predicting the thermal behaviour. For this study, both mechanical and natural ventilation were restricted. Modelling and prediction were done in Design Builder and EnergyPlus software. The computer model was validated with data measured for 20 days on the field. A correlation value of 0.85 between the predicted values and the observed values was recorded. This result shows that this energy prediction process can provide reasonable predictions in cooling loads and the effect of passive cooling in reducing indoor temperature gains. [ABSTRACT FROM AUTHOR]

It is crucial to optimize energy consumption in buildings while considering thermal comfort. The first step here involved an EnergyPlus simulation on a trade center building located in Tehran, Bandar Abbas, and Tabriz, Iran. A multi-objective optimization was then performed based on non-dominated sorting genetic algorithm II (NSGA-II) in jEPlus + EA to establish the building in the selected city where would benefit the most from implementing the radiant ceiling cooling system. Efforts were undertaken to choose environmentally-friendly materials. The final solution by Pareto charts resulted in a 52% reduction in energy consumption, a 37.3% decrease in cooling load, and a 17.4% improvement in comfort hours compared to the original design. Annual emission of greenhouse gas reduced as 167.67 tone of CO2 equivalent emission, 25.77 ton of CH4, and 0.2 ton of NO2. The mentioned algorithm was conducted for the first time on a trade center, including a DOAS system and radiant ceiling cooling system. Simultaneously, the environmental-friendly materials were dealt with. The procedure holds significant relevance for the design and optimization of buildings in Iran, especially wherever the climate is hot and humid. This approach offers advantages to the environment by reducing the impact on energy resources and utilizing environmentally-friendly materials. [ABSTRACT FROM AUTHOR]

The objective of the study is to calculate the thermal response of different types of glazing windows used in buildings to achieve a sustainable environment. However, buildings experience a significant amount of heat gain or loss through and this will affect the thermal comfort of the building's occupants. One of the essential parts of the window is the glazing. Selecting a window glazing is complicated when energy saving and day lighting aspects of a building are considered concurrently. The study involves the estimation of changes in the numerical values regarding the heating and cooling load of a residential unit in the case of replacing glazing from a double-glazed with a single-glazed window. A model of a singlestory residential structure prototype has been taken as a case study in the climate of Lahore. The calculation has been compared with values of direct solar gains, heat gains, and losses throughout the year. A quantitative research-based approach has been used. Overall, the results indicate that during summers the Double-glazed window units have 37% less heat gain and during winters 36% less heat loss as compared to Single-glazed window units. Thus, double-glazed windows are more effective in terms of energy efficiency in comparison to single-glazed windows. [ABSTRACT FROM AUTHOR]

Conventional static glazing sometimes has poor performance in energy, visual, and thermal aspects. In this thesis, a series of simulations of an office building were done to compare the performance of conventional static glazing, exterior static and kinetic shades, dynamic glazing, and dynamic glazing working together with static or kinetic shades as a combinatorial system. This thesis introduced a method for designers to make decisions among multiple shading and glazing options. A scoring system was developed to evaluate the overall performance. Energy, visual and thermal performance all had the same weight. Energy uses included annual Energy Use Intensity (EUI) and peak cooling loads of the hottest day of the year. Visual performance included maximizing daylight and minimizing glare on the fall equinox day. Thermal performance included Predicted Mean Vote (PMV) Index which determined thermal comfort based on occupants' sensations and Predicted Percentage of Dissatisfied (PPD) which indicated the levels of thermal discomfort situations. The prediction was that the combination of dynamic glazing and kinetic shade would have better comprehensive performance and earn higher scores than other options. [ABSTRACT FROM AUTHOR]

Urban overheating, intensified by climate change, poses a critical challenge in Central European cities, witnessing a rise in tropical days. Conventional mechanical cooling systems in buildings significantly contribute to carbon dioxide emissions, exacerbating global warming. In response, windcatchers—traditional Iranian natural cooling systems—emerge as a promising sustainable solution for contemporary architecture, even in non-arid climates. This research aims to evaluate windcatchers' efficacy in improving building thermal comfort in Central European climates, focusing on Vienna's urban environment. This study identifies optimal windcatcher designs by analyzing key variables: height variation, inlet dimensions, urban exposure, Building Management System (BMS) temperature thresholds, and integration with an earth tube system using Design Builder simulation software version 6. The findings reveal that a windcatcher standing at 2.5 m tall, with inlet dimensions of 0.9 m by 1.4 m, in an open, less densely populated urban setting, and with open valves when indoor temperatures surpass 22 °C, demonstrates the most effective reduction in cooling load. Moreover, both one-sided and two-sided windcatchers outperform conventional ventilation through openings. Additionally, combining a one-sided windcatcher with an earth tube system ensures efficient cooling even when exterior temperatures exceed 25 degrees Celsius. When augmented by a heat pump, this integrated system can provide heated ventilation. [ABSTRACT FROM AUTHOR]

Energy efficiency is currently a hot topic in engineering due to the monetary and environmental benefits it brings. One aspect of energy efficiency in particular, the prediction of thermal loads (specifically heating and cooling), plays a significant role in reducing the costs associated with energy use and in minimising the risks associated with climate change. Recently, data-driven approaches, such as artificial intelligence (AI) and machine learning (ML) techniques, have provided cost-effective and high-quality solutions for solving energy efficiency problems. This research investigates various ML methods for predicting energy efficiency in buildings, with a particular emphasis on heating and cooling loads. The review includes many ML techniques, including ensemble learning, support vector machines (SVM), artificial neural networks (ANN), statistical models, and probabilistic models. Existing studies are analysed and compared in terms of new criteria, including the datasets used, the associated platforms, and, more importantly, the interpretability of the models generated. The results show that, despite the problem under investigation being studied using a range of ML techniques, few have focused on developing interpretable classifiers that can be exploited by stakeholders to support the design of energy-efficient residential buildings for climate impact minimisation. Further research in this area is required. [ABSTRACT FROM AUTHOR]

Much of the active magnetic regenerator (AMR) modelling presented in the literature considers only the solid and fluid domains of the regenerator and ignores other physical effects that have been shown to be important, such as demagnetizing fields in the regenerator, parasitic heat losses and fluid flow maldistribution in the regenerator. This paper studies the effects of these loss mechanisms and compares theoretical results with experimental results obtained on an experimental AMR device. Three parallel plate regenerators were tested, each having different demagnetizing field characteristics and fluid flow maldistributions. It was shown that when these loss mechanisms are ignored, the model significantly over predicts experimental results. Including the loss mechanisms can significantly change the model predictions, depending on the operating conditions and construction of the regenerator. The model is compared with experimental results for a range of fluid flow rates and cooling loads. [ABSTRACT FROM AUTHOR]

This paper compares the heating and cooling loads between a double skin façade and a single skin façade in different and contrasting climates. The thermal and lighting properties of both types of facades are calculated, based on the hypothesis of a virtual south facing office room. The results of the above calculations show that in climates with high sunshine duration, the difference in heating and cooling loads is less for a double skin façade in comparison to a single skin facade. This difference ranges from about 30% in the Mediterranean to about 40% in the Arabian peninsula in the case that the single skin building is not equipped with automatic shading devices, whereas in the case that both buildings have automatic shading devices the above percentages range from about 5.5% to 7.5%, respectively. The same difference in heating and cooling loads between the two types of facades is significantly reduced in colder Continental climates such as Moscow, as well as temperate climates such as London. [ABSTRACT FROM AUTHOR]

The present paper introduces the notion of cool storage system and summarizes its benefits, especially the environmental ones: air emissions savings and CFC reductions. Four existing cool storage types are outlined: chilled water storage, ice storage, PCM (phase change material) cool storage and high temperature water cool storage and a commonly employed value analysis method is introduced and applied to select the best cool storage option. An evaluating method is established and the best type of cool storage is obtained. The results indicate that high temperature water cool storage is the optimal option, and the method of value analysis has applicability in selecting an optimal system. [ABSTRACT FROM AUTHOR]

Building thermal load is the energy exhausted to maintain a specific indoor temperature in comparison to the outdoor temperature. Majority of this energy makes use of a considerable amount of fossil fuels which contributes to greenhouse gases emission leading to global warming. Thermal load estimation of buildings allows people to identify infrastructures in need for retrofit for a more sustainable and smart urban management. This paper presents a small-scale study to estimate the thermal cooling load of fourteen (14) buildings in the National Science Complex of the University of the Philippines Diliman. Results of the annual cooling load calculation for the year 2020 was reported with an estimated lowest cooling load of 1,618 kW for the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) observatory and the highest cooling load of 13,484 kW for the Institute of Mathematics. The values calculated was an overestimation as the entire building was set up as a homogenous cold room without any windows or doors. For future work, it is recommended that input data be supplemented with digital surface model (DSM) and triangulated irregular network (TIN) raster data derived from Light Detection and Ranging (LiDAR) to not only categorize but assign specific values over each building group of the study area. [ABSTRACT FROM AUTHOR]

• Thermodynamic study of VCR systems based on CFC, HCFC, HFC and blends, HC, HFO and CO 2 refrigerants. • Determined component exergy destruction, exergetic efficiency, and system efficiency. • TEWI was assessed for each refrigerant to illustrate the environmental impact. • CO 2 is the potential next generation refrigerant in terms of TEWI, cost, and ASHRAE safety. • HFOs are costly but high-performance alternatives to replace currently used HFCs. This paper presents a rigorous exergy analysis of a vapor compression refrigeration system (VCRS) for the AHRI standard cooling operating conditions assessed with a constant cooling load of 50 kW. A comprehensive mathematical model has been developed to evaluate thermodynamic variables of the major components. The analysis is carried out for widely used refrigerants, namely R12, R22, R134a, R152a, R410A; next-generation low GWP refrigerants R32, R1234yf, R1234ze(E); and two natural refrigerants R600a and R744 (CO 2). First law analysis and exergetic efficiency at cycle and component level are investigated for all the refrigerants. The results indicate that R600a is the best, followed by R152a, R1234ze(E), and R1234yf in terms of COP, total exergy destruction, and exergetic efficiency. Moreover, the total equivalent warming impact (TEWI), which is the aggregation of direct impact due to refrigerant leakage and indirect impact due to electricity usage, from each system has also been assessed. The lowest and highest amount of TEWI has been found for R600a and R12 systems, respectively. This study also indicates that CO 2 is a prospective future refrigerant for its lower emission, affordability, availability, non-toxicity, non-flammability, and system compactness when the VCRS is powered by electricity generated from nuclear/renewable sources. [ABSTRACT FROM AUTHOR]