Performance based thermal comfort control (PTCC) using deep reinforcement learning for space cooling

Yoon, Young Ran,Moon, Hyeun Jun Elsevier 2019 Energy and buildings Vol.203 No.-

<P><B>Abstract</B></P> <P>With the recent increase in energy consumption in buildings, energy-saving strategies in buildings have become a priority in the energy policies of many countries. Therefore, many recent research studies have emphasized the advanced control methods to attain comfortable thermal conditions while minimizing the energy consumption in buildings. A new approach of thermal comfort control for space cooling/heating system is needed to reflect the changing indoor environment information in real time, and to control various factors (e.g., humidity, air velocity, etc.) that affect not only the temperature but also the thermal comfort.</P> <P>In this study, we propose the Gaussian process regression (GPR) for real-time thermal comfort prediction, a data-driven approach. These data-driven approaches will enable the monitoring of occupants and thermal comfort conditions based on real-time data and situational awareness. Then, based on the thermal comfort performance (PMV) prediction results obtained using the GPR, we investigated control methods involving the integration of systems, i.e., a variable refrigerant flow (VRF) system and a humidifier, instead of using simple set-temperature control for space cooling. For this purpose, deep Q-learning, which is an reinforcement learning method, was employed to derive the VRF and humidification integrated control methods. During zone operation, this algorithm learned an effective control policy based on rewards (thermal comfort and energy consumption) without relying on a thermal dynamics model. Moreover, by comparing the thermal comfort and energy consumption results with those obtained using fixed set-point (rule-based) control and performance-based comfort control for cooling, the efficiency of the proposed performance-based thermal comfort control (PTCC) was evaluated.</P> <P>As a results, it was found that PTCC yielded the optimal control action value that minimized the energy consumption while satisfying the thermal comfort conditions. In addition, applying the proposed PTCC strategy to cooling control could maintain the required performance level of thermal comfort by reflecting changing environmental conditions in real time, unlike the fixed set-point control.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PTCC (Performance based thermal comfort control) provides the optimal control scheme that minimizes energy consumption while satisfying the thermal comfort conditions. </LI> <LI> We developed a co-simulation framework based on GPR-based thermal comfort model and deep Q-learning algorithm. </LI> <LI> We developed the GPR-based PMV prediction model using commonly monitored data such as temperature and relative humidity. </LI> <LI> PTCC achieved the energy-saving control without excessively lowering the PMV and not exceeding the criteria. </LI> </UL> </P>

Combined effects of acoustic, thermal, and illumination conditions on the comfort of discrete senses and overall indoor environment

Yang, Wonyoung,Moon, Hyeun Jun Elsevier 2019 Building and Environment Vol.148 No.-

<P><B>Abstract</B></P> <P>Humans perceive environments through the interaction and integration among various sensory stimuli. While research on multisensory interaction research has increased over the last few decades in the fields of cognitive neuroscience and neurophysiology, the effect of multisensory interaction on indoor environmental perception, including thermal comfort, acoustic comfort, visual comfort, and indoor environmental comfort, has not been comprehensively understood. This study investigated the influence of multisensory interaction on acoustic comfort, thermal comfort, visual comfort, and indoor environmental comfort with three physical indoor environmental factors, i.e., acoustic, thermal, and illumination conditions in an environmentally controlled laboratory. Three homogenous room temperatures (20, 25, and 30 °C) and illuminance levels were chosen (150, 500, and 1000 lx). For each of the nine configurations, four different types of sound (babble, fan, music, and water) with four sound levels (45, 55, 65, and 75 dBA) were presented for 25 s each. Sixty university students participated in all the test configurations and provided responses on their subjective comfort of discrete senses and the overall indoor environment.</P> <P>The results indicate that acoustic comfort increases at thermoneutrality, thermal comfort increases with a decrease in the noise level at 500 lx, and visual comfort increases with a decrease in the noise level at thermoneutrality. Indoor environmental comfort increases with a decrease in the noise level at thermoneutrality in brighter conditions. Although a specific physical indoor environmental factor has the greatest effect on the corresponding sensory comfort, other physical factors also affect the perception of subjective comfort. In steady-state thermal and illumination conditions with time-varying sound stimuli, the effect of acoustic factors was the greatest on indoor environmental comfort, followed by room temperature and illuminance. Thus, it can be concluded that the impact of acoustics on indoor environmental comfort was the greatest among the three environmental factors tested in this study.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effects of multisensory interactions were investigated in steady-state thermal and luminous conditions with time-varying sound stimuli. </LI> <LI> Thermal comfort and visual comfort were affected by acoustic, thermal, and illumination conditions. </LI> <LI> Acoustic comfort was affected by acoustic and thermal conditions. </LI> <LI> All the physical factors tested in the study influenced indoor environmental comfort. </LI> <LI> Time-varying acoustic factors had a higher effect size on the overall indoor environmental comfort. </LI> <LI> Effects of gender appeared to differ in the range of each physical factor. </LI> </UL> </P>

Thermal comfort analysis in a passenger compartment considering the solar radiation effect

Moon, Joo Hyun,Lee, Jin Woon,Jeong, Chan Ho,Lee, Seong Hyuk Elsevier 2016 INTERNATIONAL JOURNAL OF THERMAL SCIENCES Vol.107 No.-

<P><B>Abstract</B></P> <P>The present study numerically investigated thermal comfort in a passenger compartment by considering the spectral solar radiation. With the use of commercial software (ANSYS Fluent V. 13.0) in which the solar load model is embedded, a three-dimensional computational fluid dynamics simulation was conducted to accurately predict thermal and flow fields under the operating conditions of a heating, ventilation, and air conditioning system. This study compared the Fanger model and the equivalent temperature model for thermal comfort analysis, together with the numerical predictions which could be used for estimation of the predicted percentage of dissatisfied, the predicted mean vote, and the equivalent temperature as the important indices in evaluating thermal comfort. From the results, the estimated temperature near the driver and passengers increased by approximately 1–2 °C when considering the spectral solar radiation. This small difference in air temperature caused a substantial variation in thermal comfort level inside the compartment. In addition, it was found that when the spectral solar radiation effect was involved, the predicted mean vote was higher than that of the case without considering the spectral radiation. Through comparison between two thermal comfort models, it was noted that the spectral solar radiation must be considered in evaluating thermal comfort levels, and unlike the Fanger model, the equivalent temperature model could predict the local variations of thermal comfort levels in the compartment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermal comfort is numerically studied in a passenger compartment. </LI> <LI> The spectral solar radiation is considered in this study for HVAC system. </LI> <LI> The Fanger model and the equivalent temperature model are compared. </LI> <LI> With solar radiation model, the maximum temperature difference of 2 °C is observed. </LI> <LI> The spectral solar radiation should be considered for thermal comfort analysis. </LI> </UL> </P>

웨어러블 디바이스의 생리 신호 기반 온열 쾌적감 예측모델 개발

이윤희(Lee, Yoonhee),전정윤(Chun, Chungyoon) 대한건축학회 2021 대한건축학회논문집 Vol.37 No.10

Thermal comfort is essential to maintain a stress-free environment in a building. This study investigated the thermal environment to develop a thermal comfort prediction model based on physiological signals and thermal comfort-related responses obtained from a wearable device. Field experiments conducted in an office during cooling and heating seasons enabled the collection of real-time thermal comfort responses and physiological signals, such as skin temperature, heart rate, and electrodermal activity of the occupant using the wearable device. We analyzed the relationships between the thermal comfort responses, physiological factors, and thermal environment to develop an accurate thermal comfort prediction model. While the skin temperature and electrodermal activity exhibited a significant relationship with the thermal state, a low heart rate was observed in a more comfortable state. Moreover, machine learning classifiers predicted the thermal comfort state achieved an accuracy of 80% in both seasons using only physiological data. Thus, the feature importance of the random forest classifier verified that physiological factors aid the prediction of thermal states significantly. The proposed prediction model can be potentially applied in heating, ventilation, and air conditioning (HVAC) control. The high performance confirmed the use of wearable devices in identifying the thermal status of building occupants.

건물 열적 성능이 거주자의 온열쾌적감, 행동적 적응 및 냉난방에너지 소비량에 미치는 영향 분석

박소현(So Hyun Park),송두삼(Doo Sam Song) 대한설비공학회 2019 대한설비공학회 학술발표대회논문집 Vol.2019 No.11

학교 운동장과 녹지공간의 UTCI, PMV, WBGT 비교 분석

윤용한 ( Young Han Yoon ),박승환 ( Seung Hwan Park ),김원태 ( Won Tae Kim ),김정호 ( Jeong Ho Kim ) 한국환경생태학회 2014 한국환경생태학회지 Vol.28 No.1

본 연구는 학교의 옥외공간 중 학생들의 휴식 및 활동량이 가장 많고, 높은 열과 낮은 열을 가지는 운동장 및 녹지공간을 대상으로 열적 쾌적성 지표 중 UTCI, PMV, WBGT를 이용하여 학생들이 느끼는 열적 쾌적성을 비교 · 분석하고자 하였다. 연구대상지는 인천광역시 학교시설(3개교)을 대상으로 하였으며, 조사기간은 2013년 7 ~ 8월까지 실시하였다. 측정항목으로 열적 쾌적성 지표의 경우 UTCI, PMV, WBGT를, 녹지구조는 녹피율과 녹지용적계수를 측정하였다. 학교별 녹지용적계수는 A학교(4.71㎥/㎡) > B학교(3.34㎥/㎡) > C학교(0.38㎥/㎡)의 순이었으며 학교별 열적 쾌적성 지표를 살펴보면, UTCI는 녹지공간 32.30~35.68℃, 운동장 40.66~42.94℃, PMV수치는 녹지공간 1.76~2.66이었으며 운동장은 모두 3으로 나타났다. WBGT는 녹지공간 26.15~31.38℃, 운동장 31.67~34.53℃이었다. 3개 지표 모두 녹지공간 대비 운동장에서 매우 불쾌적한 수준이었다. 열적 쾌적성 및 녹지와의 상관분석결과, 열적 쾌적성 지표인 UTCI, PMV, WBGT 모두 일사, 흑구온도와는 정의 상관관계를, 녹피율 및 녹지용적계수와는 부의 상관관계로 나타났다. This study of the school`s outdoor space for relaxing and activity of the two most numerous students, high heat and low heat with a green space, playground targets of thermal comfort indicators UTCI, PMV, WBGT using the thermal comfort students feeling compare the analyzed. The destination of this study, school facilities of Nam-gu, Namdong- gu, Incheon were studied and the investigation period was conducted from July to August. List of measurement, in the case of thermal comfort indicators, UTCI, PMV, WBGT was measured in the case of green, ratio of green coverage and GVZ was measured. GVZ analysis were as follows: A school (4.71 ㎥/㎡) B school (3.34㎥/㎡) C school (0.38㎥/㎡). Comparative analysis of the results of thermal comfort indicators by schools, UTCI was Green space 26.15~31.38℃ and playground 40.66~42.94℃, PMV values were 1.76 to 2.66 as a green space. WBGT was Green space 26.15~31.38℃, playground 31.67~34.53℃. Comparative analysis of the results of thermal comfort indicators UTCI, PMV, WBGT all A school, B school, C school, on the green space was comfortable levels more than playground. The results of the school type thermal comfort and green correlation analysis of thermal comfort UTCI, PMV, WBGT all solar radiation, globe temperature, and a positive correlation shown solar radiation, globe temperature is not comfortable, the higher was considered. UTCI, PMV, WBGT of thermal comfort indicator all ratio of green coverage, GVZ and negative correlation appears ratio of green coverage, GVZ was increased due to the lowering of the value of thermal comfort indicators was considered to be comfortable.

Determination of an acceptable comfort zone for apartment occupants in South Korea: An empirical analysis of cooling operation

Ryu, Ji Hye,Hong, Won Hwa,Seo, Hyun Cheol,Seo, Youn Kyu Elsevier 2017 Building and Environment Vol.125 No.-

<P><B>Abstract</B></P> <P>Occupants of apartment blocks tend to wear less clothing and exhibit lower metabolic rates than occupants of other building types. Further, the use of air conditioning systems to maintain certain comfort levels within living spaces automatically generates financial cost.</P> <P>Therefore, in this study, an acceptable comfort range that differs from the conventional normative comfort range was established. A thermal comfort control method was designed to satisfy both the economic and comfort requirements, and experiments were conducted accordingly. Subsequently, empirical data on cooling were obtained via surveys and measurements and employed to derive regression equations for the thermal sensation vote, comfort sensation vote, and percentage dissatisfaction, which indicate occupant comfort. The derived regression equations were used to graph the comfort range, and the overlap region was plotted on a psychrometric chart to enable identification of an acceptable comfort zone.</P> <P>The suggested acceptable comfort zone, which applies to apartment blocks in Korea, is outside the conventionally recommended comfort zone and can satisfy various occupant preferences, contribute to reducing energy consumption, and facilitate maintenance of comfortable living environments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Empirical cooling data were used to derive regression equations for occupant comfort. </LI> <LI> The thermal and comfort sensation votes and percent dissatisfaction were analyzed. </LI> <LI> A thermal control method meeting economic and comfort requirements was established. </LI> <LI> An acceptable thermal comfort range for Korean apartments was identified empirically. </LI> <LI> This range can reduce energy consumption and satisfy various occupant preferences. </LI> </UL> </P>

유효드래프트온도 기반 온열 쾌적범위 제어 적용에 따른 실내 열쾌적성 및 에너지 사용량 평가

진산(San Jin),윤홍익(Hong-Ik Yoon),도성록(Sung Lok Do) 대한설비공학회 2024 설비공학논문집 Vol.36 No.9

A dry bulb temperature-based HVAC control method has been traditionally used; however, the method is limited to considering the variables (e.g., humidity, air flow, mean radiant temperature, and others) that affect indoor thermal comfort. This feature may result in an uncomfortable indoor thermal environment and increase energy consumption. Thus, a thermal comfort control method based on effective draft temperature (EDT) was developed to improve these shortcomings. This study aimed to evaluate the impact of the EDT-based thermal comfort control method on indoor thermal comfort and energy consumption by developing a whole-building energy simulation model to implement the thermal comfort control method. The simulated results of indoor thermal comfort and energy consumption were analyzed by comparing the EDT-based control method to a dry bulb temperature-based one. The comparison showed that the indoor thermal environment operated with the EDT-based control method maintained a better comfort level (increased from 35.0% to 97.2% for cooling and from 87.6% to 95.5% for heating). In addition, the energy consumption decreased by 10.7% for cooling and 21.2% for heating compared to the dry bulb temperature-based control method. Therefore, operating an HVAC system using the EDT-based control method is expected to improve the indoor thermal comfort level and save energy consumption.

효율적인 에너지 사용 및 재실자 개인 맞춤화를 위한 데이터 기반 건물 HVAC 시스템

임세헌,김태근,염동우,윤성국 대한전기학회 2023 전기학회논문지 Vol.72 No.10

The predicted mean vote (PMV) model is widely used to measure thermal comfort for humans, which uses heating, ventilation, and air conditioning (HVAC) systems. However, the PMV model has limitations in satisfying individual person’s thermal comfort. As a result, a recent survey of occupants in buildings showed that the percentage of thermal discomfort is significantly high, despite the active use of the HVAC system. To address this issue, we propose a personalized thermal comfort prediction model based on machine learning that utilizes data from thermal sensation votes, indoor temperature, and humidity. We did an experiment for the data acquisition system, and four students participated. With these data, we develop a personalized thermal comfort prediction model. Among the five machine learning models, i.e., artificial neural network (ANN), linear regression (LR), support vector machine (SVM), ANN is selected showing best performamce. We formulate an optimization problem for the proposed personalized HVAC system, and its solution is derived using a genetic algorithm. The results of the thermal comfort of the personalized model are compared to the PMV model. It shows significant differences between the thermal comfort of the personalized model and the PMV model. Also, the thermal comfort performance and cost are evaluated through a building simulation.

산림복지서비스 공간 관리를 위한 가을철 도시숲의 온열환경쾌적성 평가에 관한 연구

박경자(Park, Kyeong-Ja),김진건(Kim, Jin-Gun),김웅진(Kim, Woong-Jin),안시옥(An, Siok),송도윤(Song, Doyun),신창섭(Shin, Chang-Seob),박범진(Park, Bum-Jin) 한국산림휴양복지학회 2021 한국산림휴양학회지 Vol.25 No.4

본 연구는 가을철 도시숲 온열환경요소와 인간의 쾌적성과의 관계를 규명하고 숲환경과 실내환경의 공간별 온열환경의 차이를 알아보기 위한 목적으로 수행되었다. 연구 대상지의 온열환경 측정을 위하여 기온, 습도, 풍속, 복사열을 측정하였다. 온열환경쾌적성 평가를 위해 대학생 남녀 67명이 피험자로 참가하였으며, 도시숲 환경과 실내환경에서 앉은자세로 5분간 안정을 취한 후, 심리·생리지표를 측정하였다. 심리지표로는 기분상태검사(POMS-B), 긍정부정척도(PANAS), 주관적 쾌적도를 측정하였다. 생리지표로는 심박변이도(HRV)를 측정하였다. 온열환경과 심리·생리지표 관계분석에서 풍속과 심박변이도의 HF성분 간에 음의 상관관계가 나타났으며 온열환경과 주관적 쾌적성에서는 기온, 풍속, 복사열과 온열민감도(TSV) 간의 양의 상관관계 그리고 습도와 온열민감도 간의 음의 상관관계가 나타났다. 숲환경과 실내환경과의 차이 비교 분석에서는 숲환경에서 기분상태와 심박변이도의 HF 성분이 실내환경보다 유의하게 높다는 사실이 확인되었다. 본 연구를 통하여 가을철 도시숲이 실내환경보다 쾌적하며 가을철 도시숲 내 산림복지서비스 활용 공간 계획에 있어서 온열쾌적성의 중요성을 제시할 수 있었다. This study was conducted to identify the relationship between urban forest thermal comfort factors and human comfort during the fall season and to find out the difference in thermal comfort between a forest and an indoor environment by space. Temperature, humidity, wind speed, and radiant heat were measured to measure the thermal comfort of the experimental site. Sixty-seven university students participated as subjects for the comfort evaluation. We measured psychological and physiological indicators after five minutes of sedation in the urban forest and indoor environments. Psychological indicators measure Profile of Mood State (POMS-B), Positive and Negative Affect Schedule (PANAS), Thermal Sensation Vote (TSV), and Comfort Sensation Vote (CSV) as a subjective comfort. The physiological indicators also measured the heart rate variation (HRV). Analysis of the relationship between thermal comfort and psychophysiological index showed a negative correlation between the HF power of HRV and wind speed, and a positive correlation between HF power of HRV and temperature, wind speed, radiant heat, and Thermal Sensation Vote (TSV). Comparative analysis of differences between the forest environment and the indoor environment confirmed that HF of HRV and mood conditions of humans in the forest environment are significantly higher than in the indoor environment. Through this study, the autumn urban forests are more pleasant than the indoor environment, and the importance of thermal comfort in planning a space for utilizing forest welfare services in the autumn urban forests can be suggested.