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Heating, ventilation, and air-conditioning (HVAC) systems usually have a set-point temperature control feature that uses the indoor dry-bulb temperature to control the indoor environment. However, an incorrect set-point temperature can reduce thermal comfort and result in unnecessary energy consumption. This study focuses on a derivation method for...
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The paper analyses the indoor environment in two modern intelligent buildings located in Poland. Measurements of air and globe temperatures, relative humidity and carbon dioxide concentration in 117 rooms carried out in the space of 1.5 years were presented. Thermal comfort of the occupants has been investigated using a questionnaire survey. Based...
Aggregation of heating, ventilation, and air conditioning (HVAC) loads can provide reserves to absorb volatile renewable energy, especially solar photo-voltaic (PV) generation. However, the time-varying PV generation is not perfectly known when the system operator decides the HVAC control schedules. To consider the unknown uncertain PV generation,...
Citations
... (environmental parameters), as well as metabolic rate and clothing insulation (personal parameters). Achieving thermal comfort typically involves cooling strategies such as lowering temperature [4] or increasing air velocity for a "wind chill" effect [5]. ...
Heating, Ventilation, and Air Conditioning (HVAC) systems are critical for maintaining thermal comfort in office environments which also crucial for occupant well-being and productivity. This study investigates the impact of integrating ceiling fans with higher air conditioning setpoints on thermal comfort and energy efficiency in office environments. Field measurements and questionnaire surveys were conducted to evaluate thermal comfort and energy-saving potential under varying conditions. Results show that increasing the AC setpoint from 25°C to 27°C, combined with ceiling fan operation, reduced power consumption by 10%, achieving significant energy savings. Survey data confirmed that 85% of participants reported consistent thermal sensations across all conditions, with ceiling fans effectively compensating for higher setpoints through enhanced air circulation. CFD simulations revealed that medium-speed ceiling fan operation produced the most uniform airflow distribution, with an average air velocity of 0.45 m/s, and minimized temperature variations, ensuring balanced thermal conditions. Temperature analysis showed a reduction in hotspots and cold zones, maintaining an average temperature deviation of less than ±0.5°C. Predicted Mean Vote (PMV) evaluations at a 27°C setpoint indicated improved thermal comfort, with average PMV values around −0.3, corresponding to a “neutral” thermal sensation. These findings demonstrate the effectiveness of integrating ceiling fans with HVAC systems in achieving energy efficiency and occupant comfort, offering a sustainable approach to reducing AC energy consumption in office environments.
... The townhouse was assigned to one thermal zone with a variable air volume (VAV)-HVAC system, a cooling set point of 24.4°C and a heating set point of 21.7°C. The set points were selected based on the recommended ranges for the most sustainable air conditioning practice [28]. ...
... The correlation between setpoint temperatures and the operative temperature was determined by regression analysis between the outcomes of the dependent variables of both rooms, as shown in Figure 4. A study by Han et al. [54] also found that different indoor operative temperatures on each day, signified by the same setpoint temperatures, were reflected by daily weather conditions. An acceptable range of setpoint temperatures would optimize building energy consumption, as well as occupants' comfort, and well-being. ...
The use of an air conditioner (AC) becomes essential, particularly in a hot and humid climate, to provide a comfortable environment for human activities. The setpoint is the agreed temperature that the building will meet, and the use of the lowest setpoint temperature to accelerate the cooling of indoor spaces should be avoided. A comprehensive field study was conducted under various cooling temperature settings in two student activity rooms in a university building in Malaysia, so as to understand respondents’ characteristics and behavior toward AC usage, to estimate the comfort at various indoor temperatures, to develop an adaptive model of thermal comfort in AC spaces, and to compare the comfort temperature with related local and international indoor thermal environmental standards. The findings indicated that water intake and clothing insulation affected personal thermal comfort. Moreover, the mean comfort temperature for respondents was 24.3 °C, which is within an indoor thermal comfort zone of 23–27 °C. The findings suggest that the preference of occupants living in a hot and humid region for lower temperatures means that setting temperatures lower than 24 °C might underestimate the indoor comfort temperature. Additionally, an adaptive relationship can be derived to estimate the indoor comfort temperature from the prevailing outdoor temperature.
... These efforts focus on domains like cost and time efficiency [9], safety of systems [10], material improvement [11,12], etc. Likewise, energy analysis has been of great interest and experts have tried to employ the latest technologies in this domain [13,14]. ...
Recent developments in indirect predictive methods have yielded promising solutions for energy consumption modeling. The present study proposes and evaluates a novel integrated methodology for estimating the annual thermal energy demand (DAN), which is considered as an indicator of the heating and cooling loads of buildings. A multilayer perceptron (MLP) neural network is optimally trained by symbiotic organism search (SOS), which is among the strongest metaheuristic algorithms. Three benchmark algorithms, namely, political optimizer (PO), harmony search algorithm (HSA), and backtracking search algorithm (BSA) are likewise applied and compared with the SOS. The results indicate that (i) utilizing the properties of the building within an artificial intelligence framework gives a suitable prediction for the DAN indicator, (ii) with nearly 1% error and 99% correlation, the suggested MLP-SOS is capable of accurately learning and reproducing the nonlinear DAN pattern, and (iii) this model outperforms other models such as MLP-PO, MLP-HSA and MLP-BSA. The discovered solution is finally expressed in an explicit mathematical format for practical uses in the future.
... However, this approach is not optimal since it only considers the temperature of the environment and does not include the individual's preferences for the thermal environment. This not only can increase the power consumption but also can reduce the thermal comfort of the occupants (Han et al., 2019;Hu et al., 2020;Peng and Cui, 2020). Previous reports pointed out a direct relationship of thermal comfort of the occupants to their productivity (Akimoto et al., 2010;Collinge et al., 2014), indicating the importance of thermal comfort of workers in office buildings. ...
The conventional heating, ventilation, and air conditioning (HVAC) systems are based on a set-point control approach that only considers the temperature of the environment without reflecting the thermophysiological status of the occupant. This approach not only fails to fully satisfy individual thermal preferences, but it also makes an HVAC operation energy-inefficient. One possible solution is to control the indoor thermal condition based on an accurate prediction of the occupant's thermal comfort to prevent any unnecessary energy consumption. Here, we present an artificial intelligence (AI) wearable sensor-based human-in-the-loop HVAC control system that is operated on a real-time basis reflecting the thermophysiological condition of the occupant to automatically improve their thermal comfort while reducing the energy consumption of the building. The wristband-type, AI-based, three-point wearable temperature sensor offers excellent thermal comfort prediction accuracy (93.9%), enabling a human-centric HVAC control operation. A proof-of-concept demonstration of closed human-in-the-loop HVAC control using the AI-enabled wearable sensor system confirms both the accuracy of the thermal comfort prediction and the energy-efficiency of this approach, demonstrating its potential as a new solution that improves the occupant's thermal comfort and provides building energy savings.
... J. Han et al. concentrate on an approach for deriving the optimum solution for the setpoint temperature of an HVAC system utilized in office spaces, taking into account the thermal behavior and routine changes in weather circumstances, in order to create a comfortable indoor environment by reducing unnecessary energy consumption [51]. The operative temperature is utilized in the operation of the HVAC system, and the mean radiant temperature is forecasted with a 94% degree of precision using numerous regression analysis by utilizing internal thermal environment data and meteorological information. ...
... The simulation findings suggest that the HVAC system management with the new set-point temperatures determined using the developed formula increases thermal comfort by 38.5%. Besides, this research revealed that a cooling setpoint temperature considers both the structure's thermal features and weather circumstances and efficiently boosts summertime indoor thermal comfort [51]. -14-After analyzing the above literature gaps, HVAC play an essential role in the comprehensive implementation of nZEB as HVAC is responsible for most of the energy consumption in residential buildings. ...
This master thesis aims to develop a methodology to identify the optimal operation of different HVAC system configurations for different climate conditions and building typologies. To reach the objective, the work is carried out in three main steps using dedicated tools (DesignBuilder, EnergyPlus, and eppy script (python language)) and running co-simulation. In addition, the nZEB standard established by the most recent edition of the Spanish Technical Building Code is addressed in this study through a parametric optimization study of a reference building. The effectiveness of this legislation is evaluated in terms of its capacity to disseminate the idea of building energy cost optimization and reduce the annual energy consumption in the residential sector. To this end, a reference building was designed and multiple HVAC designs were evaluated using DesignBuilder building energy simulation software and found the best optimization of HVAC solutions through EnergyPlus and eppy. In total, a set of 30 alternative scenarios was established and parametrically evaluated for 5 cities representing the 5 climatic zones of inland Spain (Bilbao, Burgos, Seville, Madrid, and Almeria) resulting in 150 simulations. The results were evaluated utilizing annual energy consumption (electricity, natural gas, and other fuels) values concerning the calibration of set point manager temperature (heating), obtaining the cost-optimal and minimum consumption levels of annual energy. It is worth mentioning that this study is mainly concentrating on the Energy Supply System (ESS), where the Energy Saving Measure (ESM) is kept unchanged, which should be reviewed in future updates.
... Thermal comfort can be obtained by a cooling situation in which the human body can readily release heat and receive a cooling sensation. The first approach to obtaining a good thermal environment is adjusting the temperature set point [2]. Furthermore, the cooling sensation can be achieved by adjusting the air velocity, which produces the "wind chill" effect [3]. ...
The airflow distribution for a large space, such as a conference hall, is quite challenging to achieve a good and uniform thermal distribution. In the recent study, insufficient quantitative knowledge has been provided, notably for the appropriate supply air temperature and air velocity for the conference hall environment. In this study, a full-scale conference hall was simulated extensively for an expo building in Taiwan. A total of nine experiment numbers were carried out with various supply air temperature and air velocity settings. Through the use of a CFD approach, this study seeks to identify the ideal parameters for a comfortable and acceptable airflow distribution and temperature, with an eye toward potential compromises with an energy-efficient approach. The results demonstrate that the temperature distribution ranges from 18 to 26 °C, indicating an acceptable indoor thermal environment, depending on the parameter settings. The best settings for providing a pleasant indoor thermal environment are with a supply air temperature and air velocity of 15 °C and 1 m/s, which can keep the PMV index between −0.5 and 0.5. Utilizing a greater temperature setting may save energy, but sufficient air velocity must be addressed in order to meet the indoor thermal conditions. Furthermore, a greater air velocity may generate more noise and disrupt the situation in the conference hall, so it must be selected specifically.
... For instance, some studies suggested the use of operative temperature as the temperature set point of the thermostat controller in order to consider the impact of both indoor air temperature and mean radiant temperature (MRT) since MRT is considered a significant influencing environmental factor for indoor thermal comfort. [13][14][15] However, the most widely investigated thermal comfort-based controls are those based on the Predictive Mean Vote (PMV) since this index takes into account most important environmental factors and personal factors that influence indoor thermal comfort including indoor air temperature, indoor humidity, indoor air velocity, mean radiant temperature, occupants' metabolic rate and occupants' clothing insulation. ...
This paper summarizes the results of a comprehensive analysis to investigate the performance of both thermal comfort-based and temperature-based controls for schools in harsh hot climates of Saudi Arabia. The analysis considers the impact of building envelope characteristics including thermal insulation level of exterior walls and air leakage rate on the ability of both control options to maintain indoor thermal comfort while minimizing cooling energy consumption. The analysis utilizes a calibrated energy model for an existing Saudi school with monitored energy consumption data. The analysis results indicated that the thermal comfort-based control is able to maintain the predicted percentage of dissatisfied (PPD) value at 5% throughout the year for any combination of the exterior wall’s R-value and air infiltration rate unlike the case of the temperature-based controls that do not maintain acceptable indoor thermal comfort conditions. However, the thermal comfort-based controls consume more cooling energy than the temperature-based controls. The analysis also revealed that the difference between the annual cooling energy of the PMV-based control and the temperature-based controls increases almost linearly with the cooling degree days of the site where the school is located. The analysis results indicate that acceptable indoor thermal comfort levels can be achieved using temperature-based controls when optimal tem- perature set points are used.
... This difference between the air temperature and operative temperature is probably due to high percentage of window surfaces and small floor plan depth that cause the mean radiant temperature to have a great effect on operative temperature. One way to overcome this problem would be to use a set point adjustment that considers the measured or predicted mean radiant temperature [102,103]. This strategy could allow horo-seasonal adjustment of the set point, which could be relevant for mild climate cities. ...
Positive energy buildings (PEB) are foreseen to help achieving global emissions reduction targets and decarbonisation. However, for vertical office spaces in urban centres the photovoltaic (PV) production area is restricted, so innovative strategies are needed. For cooling-dominated climates the extension of set point temperature associated to local control of air movement has the potential to increase the use of natural ventilation and generate a great amount energy savings. . Therefore, this study aims to identify to what extent adopting a mixed-mode operation with desk fans could help mid-rise office buildings to become NZEBs in warm climates. To verify the impact of this strategy, computer simulations were carried out with three building heights in four Brazilian cities. Results show this strategy can generate 20-40% energy savings and the set point could be extended up to 28 °C or 30 °C depending on the climate, without jeopardizing occupants’ thermal comfort. Thus, in warm climate cities, the strategy allows lower buildings to become PEBs and mid-rise buildings to become NZEBs. In addition, the demand for extra PV area is expressively reduced, increasing the viability of mid-rise PEBs. This study adds innovative knowledge for achieving PEB targets under suboptimal conditions and highlights multiple aspects that should be considered for applying this strategy.
... To determine the MRT of the space, the temperature emitted from the surface can be measured by installing a globe temperature sensor at the center of the space. It is easier to obtain the MRT by using a globe temperature sensor than by calculation; however, owing to the nature of the globe temperature sensor, there are practical difficulties in installing and using it in an indoor space [40,41]. ...
Incorporating Internet of Things (IoT) technology into the operation of buildings is expected to generate immense synergy, thereby saving energy and improving occupant comfort by overcoming the limitations of the existing system. Preventing operations in the absence of occupants can save energy, and the occupants’ preferred operating temperature should be used as the control set-point rather than the nominal temperature. In this study, IoT technology and image sensors are used to rapidly detect indoor environment changes, and a method is proposed to utilize air quality and thermal comfort as the control set-points. A real-time ventilation control algorithm is proposed based on the CO2 concentration calculated according to the number of occupants. To check the thermal comfort level, the real-time operating temperature estimated from the surface temperature data of the infrared array sensor is reflected in the comfort zone defined by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). The deficiencies in indoor environment conditions caused by the temporal and spatial lag of sensors in the old system are minimized using IoT technology, which also facilitates wireless communications. The image sensors can be used for multiple purposes based on various interpretations of the image information obtained.
