scholarly journals Improvement of the Performance Balance between Thermal Comfort and Energy Use for a Building Space in the Mid-Spring Season

2020 ◽  
Vol 12 (22) ◽  
pp. 9667
Author(s):  
Jonghoon Ahn
Keyword(s):  
Energy Consumption ◽  
Thermal Comfort ◽  
Energy Use ◽  
Learning Algorithm ◽  
Adaptive Controller ◽  
Comfort Level ◽  
Adaptive Model ◽  
Comfort Levels ◽  
Proposed Model ◽  
High Consistency

In thermal controls in buildings, recent statistical and data-driven approaches to optimize supply air conditions have been examined in association with several types of building spaces and patterns of energy consumption. However, many strategies may have some problems where high-control precision may increase energy use, or low energy use in systems may decrease indoor thermal quality. This study investigates a neural network algorithm with an adaptive model on how to control the supply air conditions reflecting learned data. During the process, the adaptive model complements the signals from the network to independently maintain the comfort level within setting ranges. Although the proposed model effectively optimizes energy consumption and supply air conditions, it achieves quite improved comfort levels about 14% more efficient than comparison models. Consequently, it is confirmed that a network and learning algorithm equipped with an adaptive controller properly responds to users’ comfort levels and system’s energy consumption in a single space. The improved performance in space levels can be significant in places where many spaces are systematically connected, and in places which require a high consistency of indoor thermal comfort. Another advantage of the proposed model is that it properly reduces an increase in energy consumption despite an intensive strategy is utilized to improve thermal comfort.

scholarly journals Performance Analyses of Temperature Controls by a Network-Based Learning Controller for an Indoor Space in a Cold Area

2020 ◽  
Vol 12 (20) ◽  
pp. 8515 ◽  
Author(s):  
Jonghoon Ahn
Keyword(s):  
Energy Consumption ◽  
Thermal Comfort ◽  
Energy Use ◽  
Fuzzy Logic Controller ◽  
Sustainable Use ◽  
Adaptive Controller ◽  
Comfort Level ◽  
Effective Control ◽  
Control Precision ◽  
Neural Network Controller

For the sustainable use of building spaces, various methods have been studied to satisfy specific conditions required by the characteristics of space types and the energy use in operation. However, several effective control approaches adopting the latest statistical tools may have problems such as higher control precision increases energy consumption, or lower energy consumption decreases their control precision. This study proposes an optimized model to reach the indoor set-point temperature by controlling the amount of heating supply air and its temperature and investigates the efficiency of an adaptive controller to maintain indoor thermal comfort within setting ranges. In the consistency of the comfort level, the fuzzy logic controller was found to be 1.76% and the artificial neural network controller to be 17.83%, respectively, more efficient than the conventional thermostat. In addition, for energy use efficiency, both of the controllers were confirmed to be over 3.0% more efficient. Consequently, the network-based controller with the adaptive controller checking comfort levels effectively works to improve both energy efficiency and thermal comfort. This improvement can be significant in places such as commercial high-rises, large hospitals, and data centers where many spaces are intensively woven with appropriate thermal environments to maintain users’ workability.

scholarly journals Abatement of the Increases in Cooling Energy Use during a Period of Intense Heat by a Network-Based Adaptive Controller

2021 ◽  
Vol 13 (3) ◽  
pp. 1353 ◽  
Author(s):  
Jonghoon Ahn
Keyword(s):  
Energy Efficiency ◽  
Thermal Comfort ◽  
Energy Use ◽  
Deterministic Model ◽  
Thermal Conditions ◽  
Adaptive Controller ◽  
High Energy ◽  
Comfort Level ◽  
Indoor Environmental Quality ◽  
Comfort Indices

Various methods to control thermal conditions of building spaces have been developed to investigate their performances of energy use and thermal comfort in the system levels. However, the high control precision used in several studies dealing with data-driven methods may cause energy increases and the high energy efficiency may be disadvantageous for maintaining indoor environmental quality. This study proposes a model that optimizes the supply air condition to effectively reach the setting values by two-way controls of the supply air conditions. In such a process, if the results of the thermal comfort level are outside the range of the initial setting values, an adaptive model starts to work to send additional signals to adjust the set-point temperature. In order to assess its efficiency, the conventional thermostat model and fuzzy deterministic model are adopted as comparators. Comparing the results of the proposed network-based model with conventional control models, an improved control performance from 15.5% to 29.3% in thermal comfort indices was identified, as well as an over 30% improvement in energy efficiency. As a consequence, the network-based adaptive control rule supervising thermal comfort indices properly operates to abate increases in its energy use without compromising its thermal comfort. This performance can be significant in places where many spaces are woven at high density, and in situations where better thermal comfort can increase users’ workability and productivity.

scholarly journals Thermal Control Processes by Deterministic and Network-Based Models for Energy Use and Control Accuracy in a Building Space

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 385
Author(s):  
Jonghoon Ahn
Keyword(s):  
Thermal Comfort ◽  
Energy Use ◽  
Deterministic Model ◽  
Learning Algorithm ◽  
Fuzzy Model ◽  
Weather Condition ◽  
Thermal Control ◽  
Comfort Level ◽  
Deterministic Models ◽  
Climate Conditions

Various control approaches for building thermal controls have been studied to improve the energy use which determines a large part of the spatial thermal quality. This research compares the performance of deterministic models and a network-based model to examine the aspects of both energy consumption and thermal comfort. The single-switch deterministic model immediately responds to indoor thermal conditions, but the network-based model sends better-fit signals derived from learned data reflecting seven different climate conditions. As a result, the network-based model improves the thermal comfort level by about 6.1% to 9.4% and the energy efficiency by about 1.8% to 39.5% as compared to a thermostat and a fuzzy model. In the case of a specific weather condition, it can be confirmed that the process of finding efficient control values based on the network-based learning algorithm is more efficient than the conventional deterministic models.

scholarly journals Comparative Analysis of Energy Use and Human Comfort by an Intelligent Control Model at the Change of Season

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6023
Author(s):  
Sung Hoon Yoon ◽  
Jonghoon Ahn
Keyword(s):  
Thermal Comfort ◽  
Intelligent Control ◽  
Energy Use ◽  
Thermal Environment ◽  
Operating Time ◽  
Adaptive Controller ◽  
Indoor Thermal Comfort ◽  
Heating And Cooling ◽  
Proposed Model ◽  
Deterministic Control

For improving control methods in the thermal environment, various algorithms have been studied to satisfy the specific conditions required by the characteristics of building spaces and to reduce the energy consumed in operation. In this research, a network-based learning control equipped with an adaptive controller is proposed to investigate the control performance for supply air conditions with maintaining the levels of indoor thermal comfort. In order to examine its performance, the proposed model is compared to two different models in terms of the patterns of heating and cooling energy use and the characteristics of operational signals and overshoots. As a result, the energy efficiency of the proposed control has been slightly decreased due to the energy consumption increased by precise controls, but the thermal comfort has improved by about 10.7% more than a conventional thermostat and by about 19.8% more than a deterministic control, respectively. This result can contribute to the reduction of actual installation and maintenance costs by reducing the operating time of dampers and the energy use of heating coils without compromising indoor thermal comfort.

scholarly journals Determination of Optimum Envelope of Religious Buildings in Terms of Thermal Comfort and Energy Consumption: Mosque Cases

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6597
Author(s):  
Ahmet Bircan Atmaca ◽  
Gülay Zorer Gedik ◽  
Andreas Wagner
Keyword(s):  
Thermal Properties ◽  
Energy Consumption ◽  
Thermal Comfort ◽  
Thermal Insulation ◽  
Energy Savings ◽  
Gain Factor ◽  
Building Envelope ◽  
Comfort Level ◽  
Humid Climate ◽  
Savings Rate

Mosques are quite different from other building types in terms of occupant type and usage schedule. For this reason, they should be evaluated differently from other building types in terms of thermal comfort and energy consumption. It is difficult and probably not even necessary to create homogeneous thermal comfort in mosques’ entire usage area, which has large volumes and various areas for different activities. Nevertheless, energy consumption should be at a minimum level. In order to ensure that mosques are minimally affected by outdoor climatic changes, the improvement of the properties of the building envelope should have the highest priority. These optimal properties of the building envelope have to be in line with thermal comfort in mosques. The proposed method will be a guide for designers and occupants in the design process of new mosques or the use of existing mosques. The effect of the thermal properties of the building envelope on energy consumption was investigated to ensure optimum energy consumption together with an acceptable thermal comfort level. For this purpose, a parametric simulation study of the mosques was conducted by varying optical and thermal properties of the building envelope for a temperature humid climate zone. The simulation results were analyzed and evaluated according to current standards, and an appropriate envelope was determined. The results show that thermal insulation improvements in the roof dome of buildings with a large volume contributed more to energy savings than in walls and foundations. The use of double or triple glazing in transparent areas is an issue that should be considered together with the solar energy gain factor. Additionally, an increasing thickness of thermal insulation in the building envelope contributed positively to energy savings. However, the energy savings rate decreased after a certain thickness. The proposed building envelope achieved a 33% energy savings compared to the base scenario.

Role of Indoor Air Distribution in Performance of Heat Pump Systems in Energy-Efficient Residential Buildings

2006 ◽  
Author(s):  
Ali A. Jal-Alzadeh-Azar ◽  
Ren Anderson ◽  
Keith Gawlik
Keyword(s):  
Energy Consumption ◽  
Heat Pump ◽  
Indoor Air ◽  
High Performance ◽  
Energy Use ◽  
Residential Buildings ◽  
Comfort Level ◽  
Air Distribution ◽  
Air Mixing ◽  
Heating Mode

This paper demonstrates the potential impact of indoor air distribution on the energy consumption of central HVAC systems with cognizance of human thermal comfort. The study focuses on a hypothetical high-performance house incorporating a split heat pump system. The air distribution of this building incorporates high sidewall supply-air registers and near-floor, wall-mounted return-air grilles. Heating-mode stratification resulting from this prevalent configuration is a prime example of situations in which challenges regarding energy efficiency, comfort, and ventilation effectiveness emerge. These challenges underline the importance of adopting a comprehensive design strategy for high-performance buildings. Two indoor air distribution scenarios were analyzed: (1) theoretically well mixed and (2) poorly mixed, representing a realistic case. The former scenario was evaluated using an analytical approach, whereas the latter was investigated through computational fluid dynamics (CFD) simulations. For heating mode, the results indicated the presence of a pronounced thermal stratification resulting from poor air mixing. At 50% of the design heating load, for the well-mixed case, the HVAC system energy consumption was significantly higher. Considerably better air distribution performance was observed with cooling mode, in which the relative energy penalty for the well-mixed scenario was noticeably less. In real-world applications where measures must be taken to achieve near perfectly mixed indoor conditions for better comfort, the energy use is expected to be even higher. However, in the absence of such measures, the thermostat setpoint is likely to be readjusted, leading to a higher energy use without necessarily improving the overall comfort level, as demonstrated in this paper. The limitation of increasing the supply-air flow rate to enhance air mixing and diffusion is also discussed in terms of the system moisture removal capability.

scholarly journals The Importance of Standardised Data-Collection Methods in the Improvement of Thermal Comfort Assessment Models for Developing Countries in the Tropics

2019 ◽  
Vol 11 (15) ◽  
pp. 4180 ◽  
Author(s):  
Carolina Rodriguez ◽  
María Coronado ◽  
Marta D’Alessandro ◽  
Juan Medina
Keyword(s):  
Developing Countries ◽  
Data Collection ◽  
Thermal Comfort ◽  
Air Conditioning ◽  
Energy Use ◽  
Comfort Levels ◽  
Geographical Regions ◽  
Adaptive Behaviours ◽  
The Tropics ◽  
Occupant Satisfaction

Thermal comfort in the built environment is one of the most defining parameters influencing energy use, environmental quality, and occupant satisfaction. Unfortunately, there is a lack of research in this area within developing countries, which are becoming increasingly urbanised and where mechanical air conditioning demands are rising. Many of these countries are adopting thermal comfort standards such as the ASHRAE Standard 55, the EN 15251, and the ISO 7730 to regulate the use of air-conditioning; even when these standards have been widely criticised for their inadequacy within geographical regions different to the ones that they were designed for. Research suggests the need to confirm these models through further post-occupancy studies and fieldwork. Deficiencies in data collection and methodologies are thought to require particular attention to develop algorithms that can predict thermal comfort levels accurately. Comprehensive strategies considering interrelated psychological, physiological and social factors are needed. This manuscript highlights gaps of research, specifically within tropical developing countries, through the analysis of Colombia as a case study. It emphasises the importance of standardised fieldwork data and gives examples of alternative collection systems. This aims to contribute to the understanding of occupant´s adaptive behaviours and their impact on the mitigation of climate change.

Indoor environmental quality and energy use evaluation of a three-star green office building in China with field study

2020 ◽  
pp. 174425912094460
Author(s):  
Yan Zhou ◽  
Jianmin Cai ◽  
Yiwen Xu
Keyword(s):  
Energy Consumption ◽  
Relative Humidity ◽  
Energy Use ◽  
Thermal Environment ◽  
Comfort Level ◽  
Office Building ◽  
Visual Environment ◽  
Actual Performance ◽  
Comparison Results ◽  
Chinese Standard

In order to get more comprehensive operation performance on indoor environment quality (IEQ) and energy consumption, a long-time measurement and a field occupants’ satisfaction survey on IEQ performance of the first three-star-operation-certified green office building in Ningbo city of China have been conducted, and environmental energy efficiency (EEE) also has been analyzed. Moreover, IEQ and energy consumption of the green case office building are compared with other green office example buildings of the same climate zone in other literatures. The results show that the actual indoor thermal environment of the green case office building isn’t quite achieving the design goals with the Chinese standard of thermal comfort level II (GB 50736). Although indoor air quality of CO2 concentration and visual environment are consistent with the design goals, the indoor relative humidity doesn’t reach the design goal in most of the year. The questionnaire survey results illustrate that the green case building has a high occupants’ satisfaction on IEQ. The comparison results show that there is no obvious difference in indoor temperature and visual environment between the green case building and the green office example buildings in other studies. The results of occupant’s satisfaction and CO2 concentration of the green case building are better than in other studies. However, the indoor relative humidity of the green case building in every season is much higher than in other researches. Energy use intensity (EUI) of the green case building is about 56.5 kWh/m2·a, which is much lower than the constraint value of the Chinese standard. The actual performance of the green case building is also evaluated by the indicator of EEE. The results of this article can provide useful reference for green building operational performance promotion and feedback for design phase optimization.

scholarly journals Model Predictive Control with Adaptive Building Model for Heating Using the Hybrid Air-Conditioning System in a Railway Station

Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1996
Author(s):  
Ruixin Lv ◽  
Zhongyuan Yuan ◽  
Bo Lei ◽  
Jiacheng Zheng ◽  
Xiujing Luo
Keyword(s):  
Energy Consumption ◽  
Model Predictive Control ◽  
Thermal Comfort ◽  
Predictive Control ◽  
Pid Control ◽  
Air Conditioning ◽  
Adaptive Model ◽  
Air Conditioning System ◽  
Building Model ◽  
Indoor Thermal Comfort

A model predictive control (MPC) system with an adaptive building model based on thermal-electrical analogy for the hybrid air conditioning system using the radiant floor and all-air system for heating is proposed in this paper to solve the heating supply control difficulties of the railway station on Tibetan Plateau. The MPC controller applies an off-line method of updating the building model to improve the accuracy of predicting indoor conditions. The control performance of the adaptive MPC is compared with the proportional-integral-derivative (PID) control, as well as an MPC without adaptive model through simulation constructed based on a TRNSYS-MATLAB co-simulation testbed. The results show that the implementation of the adaptive MPC can improve indoor thermal comfort and reduce 22.2% energy consumption compared to the PID control. Compared to the MPC without adaptive model, the adaptive MPC achieves fewer violations of constraints and reduces energy consumption by 11.5% through periodic model updating. This study focuses on the design of a control system to maintain indoor thermal comfort and improve system efficiency. The proposed method could also be applied in other public buildings.

Requirements of Air-Conditioning Systems’ Developments in Hospitals and Critical Healthcare Facilities

Volume 3 ◽  
2004 ◽  
Author(s):  
Essam E. Khalil ◽  
Ramiz Kameel
Keyword(s):  
Energy Consumption ◽  
Air Quality ◽  
Thermal Comfort ◽  
Air Conditioning ◽  
Hvac Systems ◽  
Comfort Level ◽  
Current Status ◽  
Healthcare Applications ◽  
Healthcare Facilities ◽  
Intelligent Technique

The balance between thermal comfort and air quality in healthcare facilities to optimize the Indoor Air Quality (IAQ) is the main aim of this paper. The present paper will present this balance from the viewpoint of the air conditioning design. It was found that the design of the HVAC airside systems plays an important role for achieving the optimum air quality beside the optimum comfort level. This paper highlights the importance of the proper airside design on the IAQ. The present paper introduces some recommendations for airside designs to facilitate the development of optimum HVAC systems. This paper also stresses on the factors that improve the thermal comfort and air quality for the already existed systems (for maintenance procedure). To design an optimum HVAC airside system that provides comfort and air quality in the air-conditioned spaces with efficient energy consumption is a great challenge. The present paper defines the current status, future requirements, and expectations. Based on this analysis and the vast progress of computers and associated software, the artificial intelligent technique will be a competitor candidate to the experimental and numerical techniques. Finally, the researches that relate between the different designs of the HVAC systems and energy consumption should concern with the optimization of airside design as the expected target to enhance the indoor environment. The present paper reviews the results of recent advances that are concerned with the HVAC design engineering in the healthcare applications. The following requirements are necessary for Health and hygiene considerations: • Air movements are to be restricted in and between the various hospital departments (no cross movement). • Appropriate ventilation and filtration is used to dilute and reduce contamination in the form of odour, air-borne micro organisms, viruses, hazardous chemical and radioactive substances. • Temperature and relative humidity are to be regulated and attained for various medical areas. • Environmental compliance conditions should be maintained, accurately controlled and monitored.

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