Applicable Correlations Based on Field Survey and Theory for Predicting the Indoor Thermal Climate

2012 ◽  
Vol 610-613 ◽  
pp. 2819-2822
Author(s):  
Fen E Hu ◽  
Fan Wang ◽  
Neng Bang Hou ◽  
Fei Xiang Chen
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Thermal Sensation ◽  
Environmental Parameters ◽  
Newton’S Iterative Method ◽  
Diffuse Solar Radiation ◽  
Thermal Climate ◽  
One Year ◽  
Radiant Temperature

Fanger’s PMV is the most famous thermal sensation index but it is too complex to be applied in practice. Besides, the PMV index does not take into account the effect of the hourly beam and diffuse solar radiation absorbed by the room on the indoor thermal climate. In order to obtain applicable correlations with consideration of solar radiation, a one-year measurement has been carried out in a naturally ventilated residential room in Qujing Normal University of Yunnan province, China. Based on collected data, PMV indices are calculated by using Newton’s iterative method. The correlations of the PMV and the environmental parameters — outdoor air temperature, indoor mean air temperature, mean radiant temperature, wind velocity, relative humidity, and hourly beam and diffuse solar radiation — have been studied by using the multivariable regression techniques. Lots of correlations with high correlativity have been developed in this paper. It is convenient to use these results to predict the indoor thermal climate in the natural ventilation buildings in the subtropical plateau monsoon climate.

New Correlations Including Hourly Horizontal Radiation for Predicting Indoor Thermal Environment

2011 ◽  
Vol 71-78 ◽  
pp. 2671-2674
Author(s):  
Sheng Xian Wei ◽  
Shi Mei Guo ◽  
Xi Jia He
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Environmental Parameters ◽  
Newton’S Iterative Method ◽  
Indoor Thermal Environment ◽  
One Year ◽  
Radiant Temperature

Fanger’s PMV is the most famous thermal sensation index but it is too complex to be applied in practice. Besides, the PMV index does not include the effect of horizontal solar radiation on the indoor thermal environment. In order to obtain simple and applicable correlations with consideration of solar radiation, a one-year measurement has been conducted in a naturally ventilated residential room in Qujing Normal University of Yunnan province, China. Based on collected data, PMV indices are calculated by using Newton’s iterative method. The relationships of the PMV and the environmental parameters — outdoor air temperature, indoor mean air temperature, mean radiant temperature, wind velocity, relative humidity, and hourly horizontal solar radiation — have been studied by the multivariable regression techniques. Large numbers of correlations with high correlativity have been developed in the present paper. It is convenient to use them to evaluate and predict the indoor thermal environment in the natural ventilation buildings.

Indoor Thermal Comfort Predicting Correlations in Subtropical Plateau Monsoon Climate

2012 ◽  
Vol 193-194 ◽  
pp. 231-234 ◽  
Author(s):  
Sheng Xian Wei ◽  
Qing Zhou ◽  
Shu Fen Tao ◽  
Guang Xue Chen
Keyword(s):  
Solar Radiation ◽  
Thermal Comfort ◽  
Air Temperature ◽  
Thermal Sensation ◽  
Environmental Parameters ◽  
Diffuse Radiation ◽  
Monsoon Climate ◽  
Beam Radiation ◽  
Newton’S Iterative Method ◽  
Indoor Thermal Comfort

Fanger’s PMV is the most famous thermal sensation index but it is too complex to be applied in practice. Besides, the PMV index does not include the effect of hourly solar radiation on the indoor thermal climate. In order to obtain simple and applicable correlations with considerations of outdoor hourly solar radiation, a one-year measurement was performed in a naturally ventilated residential room in Qujing Normal University of Yunnan province, China. PMV indices are calculated by using Newton’s iterative method based on the collected data. Correlations of the PMV and the environmental parameters (outdoor air temperature, indoor air temperature, mean radiant temperature, wind velocity, relative humidity, hourly beam radiation and hourly diffuse radiation) have been developed by the multivariable regression technique. It is convenient to use them to predict the indoor thermal comfort in the subtropical plateau monsoon climate.

Measurement of indoor environmental parameters and analysis of the condensation phenomenon in urban utility tunnels

2022 ◽  
pp. 1420326X2110564
Author(s):  
Chuanmin Tai ◽  
Guansan Tian ◽  
Wenjun Lei
Keyword(s):  
Water Supply ◽  
Surface Temperature ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Environmental Parameters ◽  
Dew Point ◽  
Control Mode ◽  
Safe Management ◽  
Environmental Test ◽  
Water Supply Pipeline

Condensation is a major issue in the safe operation of utility tunnels. To address the condensation problem, the indoor air temperature, relative humidity (RH) and surface temperature in an urban utility tunnel in Jining were continuously measured, and the condensation conditions were surveyed and analysed. The results indicated that under natural ventilation conditions, the air temperature in the comprehensive cabin varied from 23.4°C to 24.5°C, the RH fluctuated between 86.4% and 95.3%, and the corresponding air dew point temperature (DPT) remained in the range of 22.2°C–22.9°C. The surface temperature of the water supply pipeline ranged from 17.8°C to 18.5°C, which was far lower than the DPT in the tunnel, resulting in serious condensation. A water supply pipeline with an anti-condensation design was developed based on environmental test data. A 25-mm-thick rubber plastic sponge insulation layer was used to thermally insulate the water supply pipeline, preventing further dew condensation. Furthermore, mechanical ventilation had little effect on reducing the RH in the tunnel and may actually cause dew condensation; therefore, a ventilation control mode was proposed in this study. These results are expected to provide basic data for further research and reference for the safe management of utility tunnels.

A reflexion on the environmental effect on the transmission of COVID-19

2021 ◽  
Author(s):  
Victor L Barradas ◽  
Monica Ballinas
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Low Temperatures ◽  
Minimum Distance ◽  
Vapor Pressure Deficit ◽  
Environmental Parameters ◽  
Air Humidity ◽  
Evaporative Demand ◽  
Small Water ◽  
The Hours

<p>This research is a general reflection of the possible transmission not only of COVID-19 but of any influenza disease depending on environmental parameters such as solar radiation, air humidity and air temperature (vapor pressure deficit), evoking the Penman-Monteith model regarding the evaporation of the water that constitutes the small water droplets (aerosols) that carry the virus. In this case the evapotranspiration demand of the atmosphere with which it can be deduced that the spread of the disease will be higher in those places with less evaporative demand, that is, high air humidity and / or low temperatures, and / or low radiation intensities, and vice versa. It can also be deduced that the hours of greatest potential contagion are the night hours, while those with the lowest risk are between 2:00 p.m. and 4:00 p.m. On the other hand, in those rooms with low temperatures the contagion would be more effective. So, considering that the drops produced by a sneeze, by speaking or breathing can go beyond two meters away, it is roughly explained that the use of face masks and keeping a safe minimum distance of two meters can limit transmission of viruses and / or infections. However, this practice is not entirely safe as the environment can play an important role. What is recommended to reduce the spread of these pathogens is to produce high evaporative demands: increasing solar radiation, and increasing air temperature and reducing air humidity, which is practice that can be effective in closed rooms.</p>

Thermal comfort analyses of naturally ventilated university classrooms

2016 ◽  
Vol 34 (4/5) ◽  
pp. 427-445 ◽  
Author(s):  
Baharuddin Hamzah ◽  
Muhammad Taufik Ishak ◽  
Syarif Beddu ◽  
Mohammad Yoenus Osman
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
National Standard ◽  
Content Type ◽  
Thermal Environments ◽  
Neutral Temperature ◽  
Radiant Temperature ◽  
University Classrooms

Purpose The purpose of this paper is to analyse thermal comfort and the thermal environment in naturally ventilated classrooms. Specifically, the aims of the study were to identify the thermal environment and thermal comfort of respondents in naturally ventilated university classrooms and compare them with the ASHRAE and Indonesian National Standard (SNI); to check on whether the predicted mean vote (PMV) model is applicable or not for predicting the thermal comfort of occupants in naturally ventilated university classrooms; and to analyse the neutral temperature of occupants in the naturally ventilated university classrooms. Design/methodology/approach The study was carried out at the new campus of Faculty of Engineering, Hasanuddin University, Gowa campus. A number of field surveys, which measured thermal environments, namely, air temperature, mean radiant temperature (MRT), relative humidity, and air velocity, were carried out. The personal activity and clothing properties were also recorded. At the same time, respondents were asked to fill a questionnaire to obtain their thermal sensation votes (TSV) and thermal comfort votes (TCV), thermal preference, and thermal acceptance. A total of 118 respondents participated in the study. Before the survey was conducted, a brief explanation was provided to the participants to ensure that they understood the study objectives and also how to fill in the questionnaires. Findings The results indicated that the surveyed classrooms had higher thermal environments than those specified in the well-known ASHRAE standard and Indonesian National Standard (SNI). However, this condition did not make respondents feel uncomfortable because a large proportion of respondents voted within the comfort zone (+1, 0, and −1). The predictive mean vote using the PMV model was higher than the respondents’ votes either by TSV or by TCV. There was a huge difference between neutral temperature using operative temperature (To) and air temperature (Ta). This difference may have been because of the small value of MRT recorded in the measured classrooms. Originality/value The research shows that the use of the PMV model in predicting thermal comfort in the tropic region might be misleading. This is because PMV mostly overestimates the TSV and TCV of the respondents. People in the tropic region are more tolerant to a higher temperature. On the basis of this finding, there is a need to develop a new thermal comfort model for university classrooms that is particularly optimal for this tropical area.

scholarly journals Impact of solar reflectance of wall and road on outdoor thermal comfort - experimental study in a street canyon setup

2019 ◽  
Vol 282 ◽  
pp. 02010
Author(s):  
Kiran Kumar D E V S ◽  
Man Pun Wan ◽  
Mandi Zhou ◽  
Yongping Long ◽  
Bing Feng Ng
Keyword(s):  
Solar Radiation ◽  
Thermal Comfort ◽  
Street Canyon ◽  
Thermal Environment ◽  
Longwave Radiation ◽  
Environmental Parameters ◽  
Outdoor Thermal Comfort ◽  
Width Ratio ◽  
Diffuse Solar Radiation ◽  
Solar Reflectance

Thermal environment in an urban street canyon is primarily affected by prevailing air conditions, wind flow, solar radiation as well as thermal properties of the surrounding urban structures and pavement surfaces that affect the reflection, absorption and re-emission of solar radiation. Experiments were conducted in a 1:5 scale test setup consisting of North-South oriented street canyon (height to width ratio 1.7) located in Singapore. Test cases covering two levels solar reflectance of walls (0.35 and 0.57) and road (0.12 and 0.55) were conducted in a three-month period. Environmental parameters including direct beam and diffuse solar radiation, net radiation (incoming and outgoing shortwave and longwave radiation) and wind speed were continuously measured at the top of the canyon. Thermal comfort parameters including air temperature, relative humidity, air velocity and globe temperature were also monitored continuously inside the street canyon. When the solar reflectance of canyon surfaces increases, mean radiant temperature (MRT) reduces by up to 1.2°C during daytime and 2.5°C during the night. Such reduction leads to reduced occurrence of heat stress by 34% and 42% during the day and night times, respectively, as measured by the universal thermal comfort index (UTCI). This paper further discusses the effect of longwave radiation on MRT in the street canyon due to changes in canyon solar reflectance.

Air Environment and Energy Performance of a Building Courtyard in the Heating Season

2014 ◽  
Vol 501-504 ◽  
pp. 2231-2239
Author(s):  
Ning Bo Zhang ◽  
Yan Ming Kang ◽  
Ke Zhong ◽  
Jia Ping Liu
Keyword(s):  
Air Temperature ◽  
Natural Ventilation ◽  
Environmental Parameters ◽  
Ambient Air ◽  
Energy Performance ◽  
Building Envelope ◽  
Air Infiltration ◽  
Central Air Conditioning ◽  
Pollutant Source ◽  
New Buildings

Courtyards are now used in many new buildings in China for taking advantage of better natural ventilation and thus improving the microclimate. However, when the building is equipped with a central air-conditioning (AC) system for space heating in winter, the warm air infiltration from the heated rooms enters into the courtyard and leads to changes in the natural ventilation characteristics in the courtyard. In the present study, the air environment and energy performance of a courtyard style office building in Shanghai were monitored in winter. The internal and external environmental parameters such as air temperature, CO2and particle concentrations were measured simultaneously and continuously when the building was heated or was not in use. The results show that when there is no apparent pollutant source in the courtyard, a better microenvironment can be established and the air quality in the space is almost the same as the ambient air, because its natural ventilation is enhanced by the warm air infiltration from the heated rooms. Compared to a building without a courtyard, the building envelope heat loss can be reduced by 20% or 11% in winter for buildings with or without a corridor facing the courtyard enclosed by glass windows, respectively, due to the warm air infiltration which increases the air temperature in the courtyard.

An Unsteady Model for Natural Ventilation with Solar Chimney

2011 ◽  
Vol 354-355 ◽  
pp. 286-289 ◽  
Author(s):  
Zhong Bao Liu ◽  
Ya Xin Su
Keyword(s):  
Solar Radiation ◽  
Mass Flow Rate ◽  
Air Temperature ◽  
Mass Flow ◽  
Flow Rate ◽  
Natural Ventilation ◽  
Thermal Inertia ◽  
Solar Chimney ◽  
Air Mass ◽  
Peak Value

A one dimensional unsteady mathematical model for predicting the air mass flow rate in a solar chimney has been proposed. The thermal resistance and thermal inertia of both the glass cover and heat absorbing wall were considered in the present model. Crank-Nicolson finite difference numerical method was used to solve the differential equations. The variation of the air temperature in the solar chimney was solved by integrating the controlling equation for the air along the chimney height. Results show the absorber wall reaches its peak temperature 2 hours later with respect to the maximum ambient temperature. The air temperature in the channel varies with the solar radiation in a day and researches its peak value at about 2:00pm. The air mass flow rate increases remarkably with the increase of the channel depth when the solar radiation is higher from 11:00 am to 3:00 pm. The maximum of air mass flow rate occurs at around 2:00pm

scholarly journals The Universal Thermal Climate Index as an Operational Forecasting Tool of Human Biometeorological Conditions in Europe

2021 ◽  
pp. 193-208
Author(s):  
Claudia Di Napoli ◽  
Alessandro Messeri ◽  
Martin Novák ◽  
João Rio ◽  
Joanna Wieczorek ◽  
...  
Keyword(s):  
Air Temperature ◽  
Prediction Models ◽  
Weather Forecasting ◽  
Heat Budget ◽  
Environmental Parameters ◽  
Thermal Conditions ◽  
Personal Characteristics ◽  
Climate Index ◽  
Universal Thermal Climate Index ◽  
Thermal Climate

AbstractIn operational weather forecasting standard environmental parameters, such as air temperature and humidity, are traditionally used to predict thermal conditions in the future. These parameters, however, are not enough to describe the thermal stress induced by the outdoor environment to the human body as they neglect the human heat budget and personal characteristics (e.g. clothing). The Universal Thermal Climate Index (UTCI) overcomes these limitations by using an advanced thermo-physiological model coupled with a state-of-the-art clothing model. Several systems have been recently developed to operationally forecast human biometeorological conditions via the UTCI, i.e. by computing UTCI from the forecasts of air temperature, humidity, wind speed and radiation as provided by numerical weather prediction models. Here we describe the UTCI-based forecasting systems developed in Czech Republic, Italy, Poland, Portugal and at the pan-European scale. Their characteristics are illustrated and their potential as warning systems for thermal hazards discussed.

scholarly journals Árbol De Decisión, Aplicación Con Datos Meteorológicos/Decision Tree, Application With Meteorological Data

2020 ◽  
Author(s):  
Silvia Mariana Haro Rivera
Keyword(s):  
Data Mining ◽  
Solar Radiation ◽  
Decision Tree ◽  
Air Temperature ◽  
Meteorological Data ◽  
Barometric Pressure ◽  
Global Solar Radiation ◽  
Meteorological Variables ◽  
Diffuse Solar Radiation ◽  
Abstract Data

La minería de datos es una técnica que hoy en día se aplica en muchas áreas de las ciencias, es por ello que con el objetivo de identificar variables meteorológicas predominantes a ocho intervalos de tiempo se aplicó la técnica supervisada árbol de clasificación en data mining. La información se obtuvo de la estación Alao, misma que se encuentra ubicada a 3064 m.s.m en la provincia de Chimborazo, Ecuador. El estudio se realizó mediante código desarrollado en el software estadístico R; los datos corresponden a información por hora del año 2016, las variables analizadas fueron; temperatura del aire, humedad relativa, presión barométrica, radiación solar difusa, radiación solar global, temperatura del suelo a −20cm y velocidad de viento. El árbol mostró que la principal variable en esta zona es la radiación solar global, a horas comprendidas de 06h00 a 08h00, si ésta es mayor o igual a 120w/m2, entonces se puede determinar la presión barométrica de 09h00 a 11h00 de la mañana; y si ésta es mayor o igual que 709w/m2, entonces se predice la temperatura del aire. El árbol de decisión es una técnica que permitió identificar variables meteorológicas relevantes, en determinadas horas donde se encuentra ubicada la estación Alao. Abstract: Data mining is a technique that today is applied in many areas of science, which is why in order to identify predominant meteorological variables at eight time intervals the supervised tree classification technique was applied in data mining. The information was obtained from the Alao station, which is located at 3064 m.s.m in the province of Chimborazo, Ecuador. The study was carried out using a code developed in statistical software R, the data correspond to information by hour of the year 2016, the variables analyzes were air temperature, relative humidity, barometric pressure, diffuse solar radiation, global solar radiation, soil temperature at −20cm and wind speed. The showed that the main variable in this area is the global solar radiation, at hours between 06h00 and 08h00, if it is greater than or equal to 120w/m2, then the barometric pressure can be determined from 09h00 to 11h00 of the morning, if, and it is great than or equal to 709w/m2, then the air temperature is predicted. The decision tree is a technique that allowed us to identify relevant meteorological variables in certain hours where the Alao station is located. Palabras clave: árboles de decisión, datos meteorológicos. Keywords: decision tree, meteorological data.

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