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Among the most significant solutions suggested for estimating energy consumption and cooling load, one can refer to enhancing energy efficiency in non-residential and residential buildings. A structure's characteristics must be considered when estimating how much heating and cooling is required. To design and develop energy-efficient buildings, it can be helpful to research the characteristics of connected structures, such as the kinds of cooling and heating systems needed to ensure sui interior air quality. As an important part of energy consumption and demand of buildings, the assessment of cooling load conditions from the envelope of large buildings has not been comprehensively understood yet. In the present paper, a new conceptual system has been developed to anticipate cooling load in the sector of residential buildings. Also, the paper briefly describes the major models of the developed system to maintain continuity and concentrate on the prediction model of the cooling load. To predict cooling load, authors have modelled two methods of artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) in conjunction with teaching-learning-based optimization (TLBO). This article aims to illustrate how artificial intelligence (AI) approaches play an essential role in addressing the mentioned necessity and help estimate the optimal design parameters for various stations. The value of the multiple determination coefficient is also determined. The values of the training R² (coefficient of multiple determination) are 0.96446 and 0.97585 for TLBO-MLP and TLBO-ANFIS in the training stage and 0.95855 and 0.9721 in the testing stage, respectively, with an unknown dataset which is acceptable. The training RMSE values for TLBO-MLP and TLBO-ANFIS are 0.0685 and 0.11176 for training and 0.07074 and 0.12035 for testing, respectively, for the unknown dataset, which is acceptable. The lowest RMSE value and the higher R² value indicate the favourable accuracy of the TLBO-MLP technique. According to the high value of R² (97%) and the low value of RMSE, TLBO-MLP can predict residential buildings' cooling load. [ABSTRACT FROM AUTHOR]

Addressing the challenges of scalable and cost-effective energy performance analysis in mid to high-rise office buildings, this paper introduces a novel approach utilizing an inverse-based artificial neural network (ANN). This ANN was trained on synthetically generated heating and cooling load parameters – derived from simulations conducted in EnergyPlus – to predict characterization parameters, including the building envelope, internal heat gains, and HVAC operational parameters. Diverging from traditional forward surrogate models, this inverse surrogate model fills a critical gap in current building energy modeling approaches that are hindered by data and resource limitations. Its effectiveness is verified with a testing dataset of 3000 buildings and is further demonstrated through a case study in Ottawa, Ontario. Proving to be an efficient, cost-effective tool for energy retrofit screening, the model is enhanced by a user-friendly web-based application (Ferreira and Gunay), marking a significant advancement in accessible building energy analysis. [ABSTRACT FROM AUTHOR]

In line with the growing global trend towards energy efficiency in buildings, this paper introduces a predictive model based on an artificial neural network model to rate the performance of windows in terms of saved heating and cooling loads. A four-story building representing the conventional type of residential apartments in Iran for four climates of cold, hot and humid, hot and arid, and temperate was selected for simulation. An artificial neural network model was developed based on ten variables of U-factor, SHGC, emissivity, monthly average dry bulb temperature, monthly average percent humidity, monthly average wind speed, monthly average direct solar radiation, monthly average diffuse solar radiation, orientation, and month as the input variables. The developed ANN model computes the amount of saved heating or cooling loads as a result of using a window with defined parameters. The best architecture of 10–10-1 with MAPE, RMSE, and R2 values of 1.4%, 0.008, and 0.985, respectively showed an acceptable predictive performance of the model. The predictions of this model, in line with the four levels of window performance defined in this paper, which range from excellent performance to weak performance, constitute the final rating of a window. The rated performance of the windows used in this study showed that the performance of a window can vary in cold and hot months, and windows should be rated according to the climate in which they are being used. [ABSTRACT FROM AUTHOR]

The mismatching between the predicted and the operational performance of buildings designed to be nearly zero-energy underlines the importance to study the post-occupancy behavior, to understand if the building-HVAC system is capable to meet the variable conditions even due to the progressive climate change. The paper proposes a discussion about the operational performance of an existing nearly zero-energy building in the Mediterranean climate, during the heating and cooling seasons. The monitoring shows that the required electrical power is always lower than the nominal one, also because the external conditions are not extreme as the design ones. In the colder days, the difference in the required power is −21%. In summer, there is a delay of two hours between the external maximum temperature and the maximum required power. However, the monitored power is usually higher than the nominal one, with a maximum value of +11%. Considering all proposed combinations for the design calculation, it is demonstrated that the real performance cannot be predicted during the design, because indoor and external conditions influence the dynamic behavior of the building-HVAC system. [ABSTRACT FROM AUTHOR]

The paper presents a novel method of generating metamodels that can quantify the influence of urban form on the heating and cooling loads of dwellings for the Mediterranean climate. The goal of the metamodels is to inform the early urban design process with quick and accurate feedback on the energy demand of a given urban configuration. The proposed method generates training datasets through Monte Carlo dynamic energy simulations of a single thermal zone. The study focuses on the geometrical parameters that affect building energy balance at the urban scale, such as dwelling shape, compactness, adjacencies and shading, utilizing a set of morphological indicators to relate these parameters to heating and cooling loads. The study focuses on the Mediterranean climate of Thessaloniki, Greece and utilizes several open-source tools (Ladybug Tools, EnergyPlus and Scikit-learn) under a streamlined workflow. The metamodels, which are trained using the Random Forest algorithm are then validated on 12 real-world urban sites of Thessaloniki with a reported Mean Average Percentage Error (MAPE) of 12% and 15% for heating and cooling loads, respectively. [ABSTRACT FROM AUTHOR]

Incorporating sufficient daylight is an effective and green design strategy to improve visual comfort, energy-efficiency and sustainable building developments. However, there are more artificial lighting consumption, more cooling load and less visual comfort in internal corridors of most buildings due to the shortage of daylight. In this paper, three methods comprising questionnaire survey, numerical simulation and field measurement were integrated to study the daylighting characteristics and the critical length of the corridor with an end window or an open room in daylighting design. It began with a questionnaire survey to understand the subjective perception of the building's users on the lighting status, daylighting importance and daylighting preference in the internal corridor. Then the daylighting performance of the building corridors with the end window and the open room was simulated by Ecotect, and the analysis of the simulation data was performed through SPSS. Two models were developed for predicting the daylighting critical length of the corridors. Furthermore, a comparison of the field measurement data and the predicted results was carried out to validate the models. The results indicated that the developed models have the better accuracy and can be referred to as a guide for the initial daylighting design of buildings. [ABSTRACT FROM AUTHOR]

A mixing ventilation (MV) system integrated with a chilled ceiling (CC) cooling system will be a potential advanced heating, ventilation and air conditioning (HVAC) system in the modern buildings. This paper presented an experimental study concerning the effect of CC on the indoor air distribution with MV when the internal and external sensible cooling loads changed. The vertical distributions of indoor air temperature, air velocity and contaminant (CO2) concentration were evaluated by the vertical air temperature difference, turbulence intensity and contaminant removal effectiveness, respectively. The results showed that when chilled ceiling surface temperature ranged from 17.0 °C to 26.0 °C, the average vertical air temperature difference, turbulence intensity and contaminant removal effectiveness were 0.2 °C–0.4 °C, 30%–36% and 0.6–0.84 when both internal and external sensible cooling loads were 41.5 W/m2. Moreover, the ranges of these evaluation indices varied slightly when the internal or external sensible cooling load increased from 41.5 W/m2 to 69.5 W/m2. Hence, the chilled ceiling had a slight impact on the indoor air distribution in a room with mixing ventilation. It is interestingly found that the small vertical air temperature difference coincided with the large turbulence intensity and contaminant removal effectiveness with different internal or external cooling loads. [ABSTRACT FROM AUTHOR]

Design days are the fundamental parameters for design cooling load calculations. At present, the coincidence and coupling relationship of meteorological elements are ignored by the design-day selection methods provided in the current standards, which results in conservative and unreasonable designs. This research proposes a method of selecting design days for design cooling load calculation that considers the coincidence and correlation of meteorological elements. First, a joint distribution function is constructed; on this basis, the coincident near-extreme meteorological parameters are selected. Then three meteorological elements from a 30-year meteorological record are integrated into one single normalization parameter. Finally, a design day reflective of the variation trend of near-extreme climate conditions is selected from the meteorological record. This paper uses Tianjin in China as an example to generate the research design day. It was found that the outdoor non-guaranteed rate of the research design day is roughly consistent with the corresponding indoor thermal environment risk level. Compared with the standard Chinese design day, the peak values of the research design day are reduced effectively, and the gap between the indoor thermal environment risk level and the outdoor non-guaranteed rate is narrowed. [ABSTRACT FROM AUTHOR]

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]

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 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]

This paper presents an effective and easy to implement cooling modeling methodology for DX coils. The proposed model was created using publicly available HVAC manufacturer rating data and a reconstruction of a traditional cooling model. Specifically, a wet curve was constructed based on the manufacturer's rating data for the wet coil condition. Extrapolating a dry line from the critical point of this wet curve gave the dry coil conditions. Data from experimental tests of HVAC units are compared with the manufacturers' rating data to further validate the effectiveness of the model. Experimental results indicate that the method accurately predicts both wet-coil and dry-coil conditions (e.g., the relative error is below 9.82%, and the average absolute relative error is below 4.4%). It is hoped that this modeling methodology will not only increase the accessibility of packaged HVAC units to common users, but also better facilitate unit design, maintenance, and real-time automatic fault detection and diagnosis. [ABSTRACT FROM AUTHOR]

This paper presents a general framework of utilizing a fused measurement of the building instantaneous cooling load to improve the reliability of the chiller sequencing control in building automation systems. The fused measurement is obtained by combining the complementary advantages of two different approaches to measuring the building cooling load. One approach is the direct measurement, which calculates the building cooling load directly, using the differential water temperature and water flow rate measurements. The other is the indirect measurement, which calculates building cooling load based on chiller models using the instantaneous chiller electrical power input, etc. The combination strategy is tested using the field data collected from the central plant of the air-conditioning system in a high-rise building in Hong Kong. The confidence degree associated with the fused measurement is systematically evaluated. Periodic update of the fusion algorithm parameters is also developed to improve the performance of the fusion strategy and the chiller sequencing control. [ABSTRACT FROM AUTHOR]

Heat generation at the tool-chip interface has long been recognized as a major factor that causes sudden tool failure and shortened tool life in machining operations. Cooling fluids have traditionally been used to remove heat from the tool tip in an attempt to prolong tool life. Numerous health issues linked to the prolonged exposure of cooling fluids and pollution concerns require costly and regulated disposal process of the cooling fluid. Metal cutting using alternative cooling methods has been considered by the manufacturing industry as a possible alternative to liquid-based cooling. However, low heat removal rates or the expense of alternative cooling processes have resulted in the manufacturing industry's continued use of liquid cooling. To assist in determining the most effective cooling process a tool life model for the cutting tool is used to reduce the lifecycle testing. The work presented in this paper examines the effectiveness of an air-cooling technique based on jet impingement to prolong the effective life cycle of cutting tools. Results obtained so far clearly indicate a highly significant reduction in tool tip temperature with the air-jet arrangement, and at an economical cost. The cooling effectiveness of this technique is found to be comparable to liquid coolants with no significant decrease in tool life with air jet cooling. [ABSTRACT FROM AUTHOR]

Current work mainly deals with the design and construction of a centrifugal humidifier where the humidification and cooling are due to the soaking of the packing and the dispersion of the water from packing due to the centrifugal effect. Celdek pad 7090 is used as humidifying media, and water is used as a working substance. Experiments are performed by varying the water flow rate (WFR), air velocity (AV) and rotational packing speed. Performance parameters such as a difference in dry bulb temperature (DBT), difference in relative humidity (RH), saturation efficiency, coefficient of performance (COP) and evaporation rate (ER) are evaluated. Results showed that a water flow rate of 0.6 litres per minute (L/min), rotor speed of 150 rpm and air flow rate of 5 m/s gave the maximum performance. The current unit gave a maximum cooling efficiency, COP and ER equal to 79.23%, 5.24 and 0.90 g/s, respectively. Stationary and dynamic packing conditions are assessed where it is observed that the performance of dynamic packing is higher than that of the static case at all operating ranges. Celdek packing with dynamic conditions can be suitably applied to handle huge cooling loads, which encourages sustainable energy sources and reduces environmental pollution by limiting greenhouse gas emissions. [ABSTRACT FROM AUTHOR]

Daylight harvesting is a passive strategy that helps to increase occupants' productivity, mental and physical health as well as spatial quality and energy performance. Therefore, decisions regarding windows' size and placement are extremely important in the design process. Although beneficial in many ways, large windows are not an energy-efficient design decision in many climates. While daylight admitted through windows reduces the lighting load, it can cause excessive heat flow and increased cooling load. Energy standards limit the window-to-wall ratio (WWR) to 40% to balance the heat exchange and light gain. However, this general requirement does not account for climate, building type, lighting fixtures, etc. Advancements in the lighting industry have introduced efficient lighting fixtures that can change the WWR and lighting power density (LPD) code requirements for some climates. This study used a simulation method to investigate the impact of new lighting systems on facade design, WWR, energy performance, proposed changes to the code requirements, and daylight harvesting effectiveness in presence of efficient lighting fixtures. The results suggested a lower reliance on daylight and large windows with the use of efficient lighting fixtures and proposed a revision of the 40% prescriptive requirement due to the recent upgrades in lighting systems. [ABSTRACT FROM AUTHOR]

In building HVAC systems, a chilled water flowmeter is an important sensor. Its reading can be used to measure the real-time cooling load, which is a critical variable for the automated control of building HVAC systems, especially central chiller plants. To maintain accurate reading data, fault detection and diagnosis (FDD) of flowmeters are necessary. The available FD/FDD methods for chilled water flowmeters have several common disadvantages: (1) high requirements on sensor integrity: multiple sensors are usually involved in the construction of energy balance models; (2) complex methodology: the fault of any monitored sensor could trigger a detection hit, and a diagnosis procedure must be used to isolate the faulty sensor; and (3) the more sensors that are involved, the more difficult it is to collect fault-free historical data for the establishment of a fault-free benchmark. To address these problems, a user-friendly fault detection (FD) method for building chilled water flowmeters is proposed in this study. The proposed method requires three types of variables to function: the pump frequency, the pump power, and the measured chilled water flow rate on the header pipe. The real-time pump frequency and electrical power data that are collected by VFDs/power meters are used to estimate the true value of the chilled water flow rate with random forest regressor. An auxiliary alarm rule is proposed to tackle the tradeoff issue between detector sensitivity and false alarm rate. Field data of a real HVAC system are used in a case study to evaluate the performance of the proposed method in comparison with three existing FD methods. The results of the validation case study suggest that compared to existing FD methods, which are based on the physical pump model, ensemble learning and clustering techniques, the proposed method could realize higher hit rates and higher alarm rates when confronting different faults (bias, noise and drift) at various levels. Besides, due to the proposed alarm rule, false alarms caused by occasional data errors are completely evaded. Sensitivity analysis to the proposed method indicates that the random forest with default hyperparameters is good enough for the FD task. In brief, the good features of the proposed method (i.e., the simple workflow, low sensor requirements, accessible robust input variable data, handy estimation model, auxiliary alarm rule with tight detection threshold) render the proposed method feasible and user-friendly for engineering practice. [ABSTRACT FROM AUTHOR]

Regarding the constantly increasing cooling demands in the building sector due to climate change effects, strategies for reducing the cooling demands are vital. Among the major strategies is thermal insulation, however, overheating phenomenon during the summer months is a frequent problem in over-insulated buildings. In this study, a typical dwelling was examined in ten Mediterranean regions concerning the influence of the envelope's thermal transmittance on its cooling performance. A passive dynamic insulation system was also developed and implemented, while its cooling performance was optimized through a rule-based control strategy for the cooling period of each region. Regarding always the occupants' thermal comfort perception, increased cooling loads were recorded for most of the regions with the highly insulated envelope, which reached up to 12% for the city of Damascus, while in the hot-desert regions the picture is reversed. The dynamic insulation system displayed great potential, as its efficiency was maximum with the super-insulated envelope, resulting in up to 61% less cooling demands for the city of Seville. Finally, by disregarding the occupants' interference in the cooling system, as most of the national legislations do, higher cooling needs are calculated, that in our study reached up to 49% for the super-insulated envelope. [ABSTRACT FROM AUTHOR]

Ensuring adequate ventilation and increasing total airflow supply to occupied spaces is one of the recommendations of the World Health Organization to contain the airborne diffusion of COVID-19 virus in schools. In this article, different technical solutions are compared combining thermal recovery by a sensible or a total heat exchanger and thermodynamic recovery by a heat pump (HP). An energy analysis is carried out in two different climates and for different values of the ventilation load to the heating + cooling load ratio, to evaluate the relative advantages of the systems in old schools (mostly diffused and poorly thermal insulated) and new ones (highly thermal insulated). Results indicate that the combined HP – total heat recovery system is the most efficient solution both in colder and milder climates, giving a nonrenewable primary energy (PE) ratio of 3.9 and 3.0, respectively. PE saving compared to PE consumption varies between 6 and 20% for the different systems in old poorly thermal insulated schools, increasing remarkably in new high energy performance buildings. An economic analysis reveals that the preferable solution is the HP only. A sensitivity analysis allows to evaluate how energy and economic results vary with the parameters considered. [ABSTRACT FROM AUTHOR]

Cooling accounts for a significant amount of energy consumption in hot and humid climates, and district cooling is an energy-efficient solution. During its planning stage, an accurate and fast prediction of district cooling loads is required to assist decision-making. This study investigated the development of machine-learning-based meta-models to predict the cooling load of high-rise residential buildings at a district scale. Four machine-learning models have been evaluated, including Multiple Linear Regression, Support Vector Regression, Artificial Neural Networks (ANN), and eXtreme Gradient Boosting. The meta-model development starts with the sensitivity analysis to determine the critical parameters as independent variables. The results show that the ANN model with 30 neurons of the hidden layer, trained by eight epochs with 20% sample data, manifested superior performance when predicting monthly energy use intensity for the testing cases. A minimum of eight independent variables for the meta-model was also shown to be acceptable. [ABSTRACT FROM AUTHOR]

Mixed-mode ventilation is a design feature to improve building energy efficiency and indoor air quality. However, in practice, it does not always achieve better performance, largely due to inappropriate window operations. The research effort is also limited when exploring approaches to regulate manually operable windows. The present study found that the unregulated window operations could increase the heating load up to 21% and cooling load by 22% relative to identical buildings with fixed windows in a cold climate. To regulate the manually operable windows, we investigated the effectiveness of employing HVAC terminal devices' by improving the control sequences. The control sequences could apply setbacks on thermostat setpoints to nudge occupants to undertake window opening and closing actions. The control sequences were tested by the building performance simulation (BPS), and 3-16% of energy reductions could be achieved when control sequences encouraged occupants to undertake energy-efficient window use behaviours. [ABSTRACT FROM AUTHOR]

Global warming causes an increase in the average ambient temperatures worldwide, resulting in a further increase in the cooling load demand of indoor spaces such as buildings and agricultural greenhouses; both are critically important for humans and other living creatures. While fulfilling the cooling needs of such, there has also been a crucial constraint to reducing the energy consumption and carbon emissions associated with cooling systems. Alternative cooling approaches are being developed in hopes of replacing conventional refrigeration systems. This study first presents findings of a comprehensive comparative literature review and analysis of various active cooling cycles in three main categories: Vapor-compression cycles (vapor-compression with different hydrofluorocarbon, hydrochlorofluorocarbon, and eco-friendly refrigerants), thermally-driven cycles (absorption, adsorption, and ejector), and emerging cycles (elastocaloric, electrocaloric, magnetocaloric, thermoacoustic, thermoelectric, and thermotunneling). Then, it presents investigations on the development of a sustainability performance index to comprehensively compare different cooling approaches. The sustainability performance is derived from several parameters obtained from the environmental, economic, and energy impact of cooling. Vapor-compression cycles joined with two emerging technologies (i.e. electrocaloric and magnetocaloric) achieved high sustainability scores, where vapor-compression-R510A obtained the highest sustainability score of 76.77%, followed by electrocaloric and vapor-compression-RE170, scoring 75% and 73.3%, respectively. [ABSTRACT FROM AUTHOR]

The solar heat gain is a significant factor to be considered while designing sustainable Heating Ventilation and Air-Conditioning system for the working rooms in the future. By installing photovoltaics on rooftop, building can be insulated from heat and the cooling load requirement for the rooms can be reduced significantly. Advantages of building applied photovoltaic systems for building insulation are justified by means of measurements and modeling. Thermal and air quality measurements outside and inside rooms of similar area, under different types of PV arrays are observed and the phenomenon of solar heat gain is studied. The experiment was conducted in Perundurai, Tamil Nadu, India, in the months of February and March of 2019. Thermal infrared imaging data for room ceilings showed a reduction of up to 2.5°C under PV array compared to those with open roof. Computer simulations indicated significant differences in temperature, between ceilings covered by PV array and ceilings with open rooftop. The relative humidity inside the rooms covered by PV arrays is 10% higher as compared to rooms with open rooftop. Due to the installed 100 kWe solar photovoltaic plant, emission of nearly 100 kg CO2 is reduced per day. There is a reduction in 28.5% CO2 inside the room with elevated PV panels at the roof top compared to room without PV panels. [ABSTRACT FROM AUTHOR]

A model of a quantum harmonic oscillator Carnot refrigerator with heat resistance, internal irreversibility and heat leakage is established in this paper. Based on the quantum master equation and semigroup approach, equations of some important performance parameters, such as cooling load, coefficient of performance (COP), exergy output rate, entropy generation rate and ecological function (a criterion E = A/τ-T0σ representing the optimal compromise between exergy output rate A/τ and exergy loss rate T0σ), for the irreversible quantum Carnot refrigerator are derived. The optimal ecological performance of the refrigerator at high temperature limit is analysed using numerical examples. The effects of internal irreversibility and heat leakage on the optimal ecological performance are discussed. Performance comparisons of the quantum refrigerator under maximum ecological function, maximum COP and maximum cooling load conditions are also performed. Some special cases, i.e. endoreversible, frictionless and without heat leakage, are discussed. Taking ecological optimisation criterion as the objective makes larger improvement of the COP and the reduction in the exergy loss rate at the cost of smaller cooling load drop. [ABSTRACT FROM AUTHOR]

High reflective coatings and paints spread on the roof and walls can be very useful to reduce the cooling loads in buildings to ensure thermal comfort in the built environment. The solar reflectance of construction and cooling materials was measured with a spectrophotometer. A surface temperature monitoring campaign compared the thermal profiles of typical Italian construction materials with an innovative sustainable white paint, obtained with a special mixture of milk and vinegar of very high solar reflectance. Two building-integration cool-roof campaigns were run in the experimental building, Casa Intelligente of ENEA, in which indoor and outdoor air temperature and roof surface temperatures were monitored. This campaign, run in the summer of 2005 and 2006, allowed us to verify the influence of cool roofs to mitigate indoor air temperatures and to compare the behaviour of different cool-roof technologies. [ABSTRACT FROM AUTHOR]

The experiments have proven that the temperature level of subsoils in the summer and winter is, respectively, lower and higher than the ambient air temperature. The buried tubes in the soil can use this potential to cool or heat the ambient air. The spiral tube heat exchanger is a good choice for earth-air heat exchangers as they are buried in a fixed buried depth, and they serve higher heat transfer coefficient due to the existence of secondary flow in the cross section of tube. In this research, the spiral tube, in an earth-air heat exchanger, has been analyzed, and the performance has been evaluated in different eras and areas of use. Cities have been selected under different climatic conditions in Iran and thus the system had been simulated in both heating and cooling modes. Furthermore, the effects of various factors, such as the depth level of buried heat exchanger in soil, the velocity and the temperature of inlet air on the exhaust air temperature, as well as the thermal load absorbed by the heat exchanger, are all being investigated. Higher buried depth of the heat exchanger increases the transferred heat, while the increase in the inlet air velocity reduces the heat exchange between the soil and the air. Tabriz which is a city located in a semi-arid climate in Iran, serves the best heating and cooling loads; whereas Babolsar another city in Iran which has a humid subtropical climate, indicates the poorest performance of all in comparison to other cities and climate levels in Iran. [ABSTRACT FROM AUTHOR]

In a building-integrated agriculture (BIA) space, peak loads must be estimated to size HVAC equipment in order to maintain indoor air conditions that enhance crop growth. However, the estimation of the rates of heat gain/loss induced by the crops and their impact on heating and cooling loads have only been sparsely addressed. The present study proposes a workflow to estimate the impact of crops on a BIA space peak loads. The building, BIA space and crops – lettuces – are modeled in TRNSYS 18, while loads for design day conditions are assessed by completing a parametric study that varied the cultivated density (CD), the indoor air conditions (temperature and humidity) and the leaf area index (LAI) of the crops. Compared to the baseline peak loads, the estimated sensible heating and latent cooling peak loads of the BIA space at the highest CD for a LAI of 2.1 are 3.6 to 3.7 and 1.1 to 2.1 times higher, while being 13.3 to 14.0 and 6.0 to 9.9 times higher for a LAI of 10. The results show the importance of considering crops in estimating peak loads to size HVAC equipment and promote crop yield. [ABSTRACT FROM AUTHOR]

Estimation of a building's heating and cooling loads is an important factor taken into account implementation of energy saving measures in order to enhance energy performance of the building. In this work, the heating and cooling loads are predicted to enhance the building energy performance using different types of artificial neural networks namely, Elman network, recurrent network and back propagation network. The effect of eight input variables (relative compactness, surface area, wall area, roof area, overall height, orientation, glazing area, glazing area distribution) on two output variables (heating load and cooling load of residential buildings) is studied. The collected features are given as input to various neural networks for predicting the heating and cooling loads. The performance of the method is calculated in terms of mean absolute error, mean square error and mean relative error. Among all the networks back-propagation neural network has highest accuracy. The mean absolute error in predicting the loads is found to be 0.1 for heating load and 0.1254 for cooling load which is much better than already existing methods. The results of the work further reinforce the fact that ANN is an important tool for prediction and analysis of energy performance of a building. [ABSTRACT FROM AUTHOR]

Heat loss from a building through the ground becomes relatively important as the above-grade components of the building fabric are built more energy efficient. For annual space heating and cooling load calculations that require short computation time, with reasonable accuracy, for modelling heat losses to ground through the foundations, this study presents a new correlation-based model. The correlation algorithms were derived from the results of a commercial 3D transient heat transfer program using Artificial Neural Network. We demonstrate that for steady-state heat loss through slab-on-ground, the proposed correlation model agrees with the CSIRO analytical solution within 6.8%, and for transient heat loss through slab-on-ground and basement the new model agrees with a well validated commercial 3D heat transfer program. The new simplified approach presented covers most foundation configurations of interest, with low processing requirements, and is ideal for use in building energy performance simulations due to the short computation time. [ABSTRACT FROM AUTHOR]

Proper sizing of central air-conditioning (AC) systems is essential for high energy efficiency and desired levels of thermal comfort. However, due to the lack of accurate information at the design stage to predict the building peak cooling load and AC system performance, uncertainty exists in the sizing process. To directly deal with the uncertainty, uncertainty-based proper sizing has been developed and studied by many researchers in recent years. Unfortunately, there is neither a systematic review of the uncertainty problem nor a review of proper uncertainty-based sizing. Therefore, this study presents a comprehensive review of the uncertainty in the sizing of central AC systems and outlines the uncertainty-based sizing procedures, with the purpose of helping AC researchers and practitioners understand the sizing procedure and relevant techniques developed recently and, thus, promoting the uncertainty-based sizing strategy. [ABSTRACT FROM AUTHOR]

The impact of the increasing technomass (TM) on cooling demand in buildings is explored for cities in South America. The entangled double nature of the building--environment interrelation in an urban context is analyzed. The research question is whether an increase in the building density produces a superlinear increase of energy consumption at the urban scale. Advanced spatially explicit quantitative methods are used to select representative samples of the urban environment and to quantify the volumes of TM in four South American cities. Principal component analysis is used to extract representative urban tissue categories. The Urban Weather Generator tool is used to produce the urban weather data used in building performance simulations. The results confirm the superlinear dependence of the total cooling consumption of each sample in relation to the existing TM in areas with high-rise buildings due to the combined primary and secondary effects, namely, the increase of the total energy needs and the increase of air temperature due to the urban heat island effect. The great significance of the secondorder effect poses challenges to current assessments performed on the basis of consumption per m2. The use of the TM indicator can promote the development of climate-sensible urban planning. [ABSTRACT FROM AUTHOR]

The considerable performance implications of occupants’ presence and behaviour in buildings render the inclusion of corresponding models in simulation applications both necessary and critical. In this context, an important question concerns the implications of different occupancy modelling approaches for simulation results. The present contribution addresses this issue by modelling an office building to obtain heating and cooling demands and peak loads. To represent occupants’ presence patterns in the model, standard-based and observed diversity profiles, stochastic realizations of these profiles, and the full-year observational occupancy data are deployed. Subsequently, a sequence of simulation runs – involving Monte-Carlo simulations of models with stochastic profiles – provides the distributions of results. The study suggests that the viability of simulation results regarding building-level annual heating and cooling demands and peak heating and cooling loads is primarily dependent on the availability of reliable estimations of actual occupancy, rather than stochastic or non-stochastic representation of presence patterns. [ABSTRACT FROM AUTHOR]

Undisturbed ground temperatures are often required for engineering applications, such as analyses of building heating and cooling load calculations and design of ground heat exchangers. In two companion articles, an automated procedure for generating a world-wide dataset of typical year ground temperatures has been developed and validated against measured results at 19 Soil Climate Analysis Network sites. This procedure relies on a two-harmonic relationship and five weather-related constants—annual average ground temperature, two temperature amplitudes, and two phase lags—to predict the undisturbed ground temperatures. These constant values generated for 4092 sites world-wide covered by short and tall grass are summarized in Appendix A and B in this article. In the United States, a one-harmonic model which relies on three constant values to estimate the ground temperatures is commonly used. The ASHRAE Handbook and ASHRAE District Heating Guide provide these constant values in North America and in a world-wide range, respectively. The estimated typical year ground temperatures using the Xing and Spitler procedure are compared to the measured results at the 19 Soil Climate Analysis Network sites, it shows the mean root mean square errors of all sites are within 1.3°C–1.6°C (2.3°F–2.9°F) at 5–100 cm (2–40″) depths, which are 0.7°C–1.4°C (1.3°F–2.5°F) lower than the root mean square errors given by the commonly used procedures in United States. Estimations of the peak (maximum/minimum) ground temperature over multiple years are also important. Thus, a correction factor β is introduced in the two-harmonic model, the newly developed simplified design model could now be used to predict typical year ground temperatures and peak ground temperatures of multiple years. For a typical year, the correction factor is set to be 1. It is suggested that the correction factor of 1.6 to be chosen, so as to use the simplified design model to estimated maximum/minimum ground temperatures of multiple years. [ABSTRACT FROM PUBLISHER]

Heating and cooling load calculations are critical to size HVAC systems and determine energy use of their operations. The ASHRAE recommended heating load calculation model is most commonly used for heating load calculations. It adopts a simplified approach by considering only steady-state conductive heat transfer. However, due to thermal storage effect, heat generated in daytime may still be stored in buildings and released at a later time. Such assumption leads to significantly over-sized heating systems which are usually accompanied by high initial cost and higher cost of energy use. This study therefore examines the thermal response and passive storage characteristic of heavy construction for typical office building in continental United States. By allowing space air to drift to reasonably lower values, buildings need to be warmed up before being occupied in the morning. The worst case conditions might happen during warm-up or beginning of occupied hours. This article evaluates the optimal size of heating system which satisfies thermal comfort while taking advantage of passive thermal storage. Results show varying downsizing opportunities ranging from 14% to 54% across the United States. These results have the potential of establishing new heating device design standards for certain climate classifications. [ABSTRACT FROM PUBLISHER]

The use of low exergy cooling concepts in the built environment can reduce the reliance upon high-quality energy sources. However, the application of such cooling systems can result in whole-body and local discomfort of the occupants. The differences in thermal perception between genders are studied to understand how convective and radiant cooling may impact upon comfort. Physiological and thermal sensation data indicate significant differences between the different experimental cases for each gender. For the prediction of thermal sensation and thermal comfort under non-uniform conditions, the operative temperature only is not sufficient. Combined local factors play an important role in the comfort assessment. For females, the local sensations and skin temperatures of the extremities have a significant influence on whole-body thermal sensation and are therefore important to consider under non-uniform environmental conditions. The results show that existing thermal comfort standards are not suitable for application under non-uniform thermal environments for the assessment of thermal comfort. Local effects, as local skin temperatures, play an important role in the whole-body thermal assessment. Therefore, the operative temperature alone is insufficient for the assessment of thermal comfort. L'utilisation de concepts de refroidissement basse énergie dans le cadre bâti peut réduire la dépendance envers des sources d'énergie de haute qualité. Cependant, l'application de tels systèmes de refroidissement peut se traduire par un inconfort local ou du corps tout entier chez les occupants. Les différences quant à la perception thermique entre les sexes sont étudiées afin de comprendre comment un refroidissement par convection et par rayonnement peut avoir un impact sur le confort. Les données relatives aux sensations physiologiques et thermiques indiquent qu'il existe des différences significatives entre les différents cas expérimentaux pour chaque sexe. Pour pouvoir prévoir les sensations thermiques et le confort thermique dans des conditions non uniformes, la seule température opérative n'est pas suffisante. La combinaison des facteurs locaux joue un rôle important dans l'évaluation du confort. Concernant les femmes, les sensations locales et la température de la peau aux extrémités ont une influence significative sur la sensation thermique ressentie par l'ensemble du corps et doivent par conséquent être prises en compte dans des conditions environnementales non uniformes. Les résultats montrent que les normes de confort thermique existantes ne sont pas adaptées à une application dans des environnements thermiques non uniformes pour l'évaluation du confort thermique. Les effets locaux, tels que la température locale de la peau, jouent un rôle important dans l'évaluation thermique au niveau de l'ensemble du corps. La seule température opérative est par conséquent insuffisante pour l'évaluation du confort thermique. Mots clés:refroidissement, sexe, environnements thermiques non uniformes, physiologie, confort thermique, sensation thermique [ABSTRACT FROM AUTHOR]

The performances of endoreversible Carnot refrigeration and heat pump cycles with loss of heat resistance and finite piston speeds are analysed and optimized by using the combination of finite time thermodynamics, finite speed thermodynamics and direct method. The unequal finite piston speed model on four branches is adopted. Expressions of cooling load of endoreversible Carnot refrigeration cycle and of heating load of endoreversible Carnot heat pump cycle are derived with a fixed cycle period and unequal finite piston speeds on the four branches. Numerical examples show that there exist optimal expansion ratios, which lead to maximum cooling load and maximum heating load for the fixed coefficient of performance (COP), respectively. The maximum cooling load, maximum heating load, optimal ratios of finite piston speeds and optimal hot- and cold-side working fluid temperatures versus COP characteristics for the endoreversible Carnot refrigeration and heat pump cycles are obtained. Moreover, the effects of design parameters on the performances of the two cycles are discussed. [ABSTRACT FROM AUTHOR]

In this work, we investigated the interplay and the influence of lighting and blind control models on the heating, cooling, and lighting energy loads of an office room. By including different stochastic models for occupancy and appliances, we built a complete simulation environment based on the building simulation program IDA ICE. For control models, we implemented different strategies, including a simple on/off scheme, a realistic model of occupants, and an optimized control. In literature, the results are often compared with simple on/off schemes, which are not hard to beat in terms of performance. With an optimal control, the real saving potential is assessed, which can be used as benchmark case for comparison with other control models. Results based on annual simulations show that active occupants can reduce energy consumption by up to 50% from a worst-case scenario, whereas advanced controllers can further reduce the consumption by another 60%. [ABSTRACT FROM AUTHOR]

A vertical temperature gradient is known to occur in an enclosure that is ventilated by stratified air distribution (STRAD) methods. Thermal stratification offers distinct energy-saving possibilities. For example, a portion of heat gains can be excluded when calculating the air supply rate and the air-conditioning load. The cooling load reduction of a heat source depends primarily on its vertical location and radiant and convective split. In this study, an effective cooling load factor (ECLF) was defined to calculate the effective heat gains, which can be used by design engineers for the determination of the reduced-supply airflow rate and reduced cooling coil loads for common- and split-return/exhaust configurations with STRAD. Numerical simulations used to obtain these factors for various internal heat sources in a small office were presented, and on-site measurements were carried out to validate the performance of computational fluid dynamics in predicting the thermal stratification in large spaces. A fully developed database of ECLFs will be very useful when designing such systems. [ABSTRACT FROM AUTHOR]