Identification of the Minimum Number of Measurements Required for Thermal Comfort Assessment in Large Workplaces

2019 ◽  
Vol 63 (7) ◽  
pp. 729-742
Author(s):  
Paolo Lenzuni ◽  
Pierangelo Tura ◽  
Pierfrancesco Cervino
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Significant Loss ◽  
Spatial Inhomogeneity ◽  
Main Window ◽  
Room Size ◽  
Synthetic Index ◽  
Minimum Number ◽  
The Difference ◽  
A Minor

Abstract Optimization of resources is the key to improve our ability to perform multiple tasks with limited time and money. In the context of thermal comfort assessment, optimization becomes important in large rooms where tens of individuals perform similar tasks. This work focuses on the identification of the minimum number of measurement points that allows an accurate description of the thermal environment. Accuracy of description is assumed if no significant loss of information is associated to the transition from the ‘primary’ thermal map based on all available measurement points to a ‘secondary’ thermal map based on a reduced set of measurement points. The concept of ‘no significant loss’ is quantified by requiring that the difference in PMV (Predicted Mean Vote) between the two maps is kept <0.1 in the vast majority (95%) of points. PMV is a standardized synthetic index that is used worldwide for quantifying thermal comfort (ISO 7730, 2005) taking into account both environmental (thermo-hygrometric) and personal (activity, clothing) quantities. We show that the uncertainty induced by the degraded resolution of the thermal map has a limited impact on the overall uncertainty on PMV. Application of the method to a few test environments shows that the room size perpendicular to the main window and the windows orientation play the largest role in determining spatial inhomogeneity in thermal maps. A minor concurring factor is the room area.

scholarly journals Towards Sustainable Development: Building’s Retrofitting with PCMs to Enhance the Indoor Thermal Comfort in Tropical Climate, Malaysia

2021 ◽  
Vol 13 (7) ◽  
pp. 3614
Author(s):  
Zeyad Amin Al-Absi ◽  
Mohd Isa Mohd Hafizal ◽  
Mazran Ismail ◽  
Azhar Ghazali
Keyword(s):  
Climate Change ◽  
Sustainable Development ◽  
Thermal Comfort ◽  
Phase Change Materials ◽  
Thermal Environment ◽  
High Energy ◽  
Transition Temperatures ◽  
Indoor Thermal Environment ◽  
Adaptive Thermal Comfort ◽  
The Difference

Building sector is associated with high energy consumption and greenhouse gas emissions, which contribute to climate change. Sustainable development emphasizes any actions to reduce climate change and its effect. In Malaysia, half of the energy utilized in buildings goes towards building cooling. Thermal comfort studies and adaptive thermal comfort models reflect the high comfort temperatures for Malaysians in naturally conditioned buildings, which make it possible to tackle the difference between buildings’ indoor temperature and the required comfort temperature by using proper passive measures. This study investigates the effectiveness of building’s retrofitting with phase change materials (PCMs) as a passive cooling technology to improve the indoor thermal environment for more comfortable conditions. PCM sheets were numerically investigated below the internal finishing of the walls. The investigation involved an optimization study for the PCMs transition temperatures and quantities. The results showed significant improvement in the indoor thermal environment, especially when using lower transition temperatures and higher quantities of PCMs. Therefore, the monthly thermal discomfort time has decreased completely, while the thermal comfort time has increased to as high as 98%. The PCM was effective year-round and the optimum performance for the investigated conditions was achieved when using 18mm layer of PCM27-26.

scholarly journals Environment in poultry production covered with thermal and aluminum roofing tiles

2015 ◽  
Vol 35 (2) ◽  
pp. 206-214
Author(s):  
FERNANDO G. DE OLIVEIRA ◽  
WANESSA M. GODOI ◽  
ROBERTA PASSINI
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Radiant Heat ◽  
Poultry Production ◽  
Thermal Indices ◽  
Significance Level ◽  
Temperature And Humidity ◽  
Humidity Index ◽  
The Difference ◽  
Globe Temperature

Brazil is a country of tropical climate, a fact that hinders the poultry production in the aspect of thermal comfort. Thus, we aimed to evaluate the thermal environment in commercial poultry houses with different covers during the months of December 2012 to May 2013, in the municipality of Rio Verde, Goiás. The experimental design was completely randomized in split plots with factorial arrangement of treatments 2x3, being two shed models (thermal and aluminum roof tiles) and three sections within each shed (initial, central and final) for 182 days, having the days as replicates. The thermal environment was assessed through thermal comfort indices: Temperature and Humidity Index, Black Globe Temperature and Humidity Index, Radiant Heat Load and Enthalpy. The data was analyzed by SISVAR 5.1., through the analysis of variance, the Scott Knott test used to compare the means, considering a significance level of 1%. The results showed a significant statistical difference between the sheds and the points assessed (P < 0.05). The thermal shed had the lowest values for the environmental variables (Dbt and Bgt) and thermal indices studied, but larger values for the RH compared to the shed with aluminum covering. The use of thermal covers minimizes the difference in temperature range throughout various times of the day, being at 14:00 o'clock the prominence time to others.

scholarly journals Investigation of thermal comfort and the nozzle usage behaviour in aircraft cabins

2017 ◽  
Vol 28 (1) ◽  
pp. 118-131 ◽  
Author(s):  
Zhaosong Fang ◽  
Hong Liu ◽  
Baizhan Li ◽  
Andrew Baldwin
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Ventilation System ◽  
Body Part ◽  
Upper Body ◽  
Body Parts ◽  
Aircraft Cabins ◽  
Minimum Number ◽  
Personal Ventilation

In order to understand passengers’ demand for thermal comfort in aircraft cabins, we carried out a measurement of thermal environment parameters and thermal comfort field survey in an aircraft cabin under cruising at altitude in both summer and winter. The results showed that the air temperature studied was always kept within the range of 25℃ to 28℃ and the relative humidity was maintained within the range of 20% to 35%. The Mean Thermal Sensation Vote (MTSV) of passengers’ back and feet was higher than other local body parts, with lower air movement sensation. The MTSV of passengers in winter was higher than that in summer. Due to the muggy thermal environment, more than 60% of passengers advocated that it was necessary to utilize the personal ventilation system. In their usage of the personal ventilation nozzle, more than half of these passengers chose to cool upper body parts, only a minimum number of passengers opened the nozzle to direct airflow to their head. Therefore, we concluded that the position of the personal ventilation nozzle should be as close to the upper body part of a passenger’s body as possible, making it more convenient and effective to regulate passengers’ thermal comfort.

scholarly journals Evaluating the Connection between Thermal Comfort and Productivity in Buildings: A Systematic Literature Review

Buildings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 244
Author(s):  
Ana Maria Bueno ◽  
Antonio Augusto de Paula Xavier ◽  
Evandro Eduardo Broday
Keyword(s):  
Literature Review ◽  
Thermal Comfort ◽  
Systematic Literature Review ◽  
Thermal Environment ◽  
Final Analysis ◽  
Personal Factors ◽  
Exclusion Criteria ◽  
Environment Variables ◽  
Main Factors ◽  
Combination Of Methods

The thermal environment is one of the main factors that influence thermal comfort and, consequently, the productivity of occupants inside buildings. Throughout the years, research has described the connection between thermal comfort and productivity. Mathematical models have been established in the attempt to predict changes in productivity according to thermal variations in the environment. Some of these models have failed for a number of reasons, including the understanding of the effect that several environment variables have had on performance. From this context, a systematic literature review was carried out with the aim of verifying the connection between thermal comfort and productivity and the combinations of different thermal and personal factors that can have an effect on productivity. A hundred and twenty-eight articles were found which show a connection between productivity and some thermal comfort variables. By means of specific inclusion and exclusion criteria, 60 articles were selected for a final analysis. The main conclusions found in this study were: (i) the vast majority of research uses subjective measures and/or a combination of methods to evaluate productivity; (ii) performance/productivity can be attained within an ampler temperature range; (iii) few studies present ways of calculating productivity.

scholarly journals Development of a Deep Neural Network Model for Estimating Joint Location of Occupant Indoor Activities for Providing Thermal Comfort

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 696
Author(s):  
Eun Ji Choi ◽  
Jin Woo Moon ◽  
Ji-hoon Han ◽  
Yongseok Yoo
Keyword(s):  
Neural Network ◽  
Thermal Comfort ◽  
Deep Neural Network ◽  
Mean Squared Error ◽  
Thermal Environment ◽  
The Body ◽  
Estimation Accuracy ◽  
Accurate Estimation ◽  
Body Parts ◽  
Joint Location

The type of occupant activities is a significantly important factor to determine indoor thermal comfort; thus, an accurate method to estimate occupant activity needs to be developed. The purpose of this study was to develop a deep neural network (DNN) model for estimating the joint location of diverse human activities, which will be used to provide a comfortable thermal environment. The DNN model was trained with images to estimate 14 joints of a person performing 10 common indoor activities. The DNN contained numerous shortcut connections for efficient training and had two stages of sequential and parallel layers for accurate joint localization. Estimation accuracy was quantified using the mean squared error (MSE) for the estimated joints and the percentage of correct parts (PCP) for the body parts. The results show that the joint MSEs for the head and neck were lowest, and the PCP was highest for the torso. The PCP for individual activities ranged from 0.71 to 0.92, while typing and standing in a relaxed manner were the activities with the highest PCP. Estimation accuracy was higher for relatively still activities and lower for activities involving wide-ranging arm or leg motion. This study thus highlights the potential for the accurate estimation of occupant indoor activities by proposing a novel DNN model. This approach holds significant promise for finding the actual type of occupant activities and for use in target indoor applications related to thermal comfort in buildings.

scholarly journals How Can We Adapt Thermal Comfort for Disabled Patients? A Case Study of French Healthcare Buildings in Summer

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4530
Author(s):  
Youcef Bouzidi ◽  
Zoubayre El Akili ◽  
Antoine Gademer ◽  
Nacef Tazi ◽  
Adil Chahboun
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Residential Buildings ◽  
Linear Regression Analysis ◽  
Environmental Parameters ◽  
Physical Parameters ◽  
Mean Radiant Temperature ◽  
Operative Temperature ◽  
Neutral Temperature ◽  
Radiant Temperature

This paper investigates adaptive thermal comfort during summer in medical residences that are located in the French city of Troyes and managed by the Association of Parents of Disabled Children (APEI). Thermal comfort in these buildings is evaluated using subjective measurements and objective physical parameters. The thermal sensations of respondents were determined by questionnaires, while thermal comfort was estimated using the predicted mean vote (PMV) model. Indoor environmental parameters (relative humidity, mean radiant temperature, air temperature, and air velocity) were measured using a thermal environment sensor during the summer period in July and August 2018. A good correlation was found between operative temperature, mean radiant temperature, and PMV. The neutral temperature was determined by linear regression analysis of the operative temperature and Fanger’s PMV model. The obtained neutral temperature is 23.7 °C. Based on the datasets and questionnaires, the adaptive coefficient α representing patients’ capacity to adapt to heat was found to be 1.261. A strong correlation was also observed between the sequential thermal index n(t) and the adaptive temperature. Finally, a new empirical model of adaptive temperature was developed using the data collected from a longitudinal survey in four residential buildings of APEI in summer, and the obtained adaptive temperature is 25.0 °C with upper and lower limits of 24.7 °C and 25.4 °C.

Thermal environment and thermal comfort built by decoupled radiant cooling units with low radiant cooling temperature

2021 ◽  
Vol 206 ◽  
pp. 108342
Author(s):  
Yuying Liang ◽  
Nan Zhang ◽  
Huijun Wu ◽  
Xinhua Xu ◽  
Ke Du ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Cooling Temperature ◽  
Radiant Cooling

Producing Steam by Spraying Water on a Heated Bed of Steel Spheres

2021 ◽  
pp. 1-42
Author(s):  
D. Jordan Bouchard ◽  
HengSheng Yang ◽  
Sanjeev Chandra
Keyword(s):  
Particle Size ◽  
Thermal Mass ◽  
Steam Generation ◽  
Bed Porosity ◽  
The Media ◽  
Effect Of Particle Size ◽  
The Difference ◽  
Rate Of Evaporation ◽  
A Minor ◽  
Counter Current

Abstract Steam generators used in industrial baking ovens operate by pouring or spraying water on a preheated thermal mass. This paper presents a methodology to quantify the amount of steam generated from a thermal mass along with experiments to determine the effect of particle size and porosity on steam generation. Three sizes of steel spheres, 0.6 mm, 8 mm, and 16 mm in diameter, were used to construct porous media beds that were preheated in an oven after which water was sprayed onto them from a full-cone nozzle for a fixed duration. The weight of the heated bed and the impinging water were recorded during spraying. The difference in weight change when spraying on heated and unheated beds gave the rate of evaporation. Thermocouples were used to record the internal temperature of the bed. Steam generation rate increased with particle size while bed porosity had only a minor influence. The counter-current flow of steam within the media bed disrupts the downward flow of water enough to leave pockets of hot material, reducing steam production. To maximize steam generation the media size, material, and spray time should be matched to ensure the surfaces of particles remain above the boiling point of water during spraying.

scholarly journals The Street Air Warming Phenomenon in a High-Rise Compact City

Atmosphere ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 402 ◽  
Author(s):  
Xiaoxue Wang ◽  
Yuguo Li ◽  
Xinyan Yang ◽  
Pak Chan ◽  
Janet Nichol ◽  
...  
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Thermal Environment ◽  
Urban Climate ◽  
Pollutant Dispersion ◽  
Urban Morphology ◽  
Air Temperatures ◽  
Significant Difference ◽  
Sensitivity Studies ◽  
Weather Stations

The street thermal environment is important for thermal comfort, urban climate and pollutant dispersion. A 24-h vehicle traverse study was conducted over the Kowloon Peninsula of Hong Kong in summer, with each measurement period consisting of 2–3 full days. The data covered a total of 158 loops in 198 h along the route on sunny days. The measured data were averaged by three methods (direct average, FFT filter and interpolated by the piecewise cubic Hermite interpolation). The average street air temperatures were found to be 1–3 °C higher than those recorded at nearby fixed weather stations. The street warming phenomenon observed in the study has substantial implications as usually urban heat island (UHI) intensity is estimated from measurement at fixed weather stations, and therefore the UHI intensity in the built areas of the city may have been underestimated. This significant difference is of interest for studies on outdoor air temperature, thermal comfort, urban environment and pollutant dispersion. The differences were simulated by an improved one-dimensional temperature model (ZERO-CAT) using different urban morphology parameters. The model can correct the underestimation of street air temperature. Further sensitivity studies show that the building arrangement in the daytime and nighttime plays different roles for air temperature in the street. City designers can choose different parameters based on their purpose.

scholarly journals Energy-saving potential of intermittent heating system: Influence of composite phase change wall and optimization strategy

2020 ◽  
pp. 014459872096921
Author(s):  
Yanru Li ◽  
Enshen Long ◽  
Lili Zhang ◽  
Xiangyu Dong ◽  
Suo Wang
Keyword(s):  
Energy Consumption ◽  
Thermal Comfort ◽  
Phase Change ◽  
Air Temperature ◽  
Indoor Air ◽  
Thermal Environment ◽  
Optimization Strategy ◽  
Indoor Thermal Environment ◽  
Indoor Thermal Comfort ◽  
Intermittent Heating

In the Yangtze River zone of China, the heating operation in buildings is mainly part-time and part-space, which could affect the indoor thermal comfort while making the thermal process of building envelope different. This paper proposed to integrate phase change material (PCM) to building walls to increase the indoor thermal comfort and attenuate the temperature fluctuations during intermittent heating. The aim of this study is to investigate the influence of this kind of composite phase change wall (composite-PCW) on the indoor thermal environment and energy consumption of intermittent heating, and further develop an optimization strategy of intermittent heating operation by using EnergyPlus simulation. Results show that the indoor air temperature of the building with the composite-PCW was 2–3°C higher than the building with the reference wall (normal foamed concrete wall) during the heating-off process. Moreover, the indoor air temperature was higher than 18°C and the mean radiation temperature was above 20°C in the first 1 h after stopping heating. Under the optimized operation condition of turning off the heating device 1 h in advance, the heat release process of the composite-PCW to the indoor environment could maintain the indoor thermal environment within the comfortable range effectively. The composite-PCW could decrease 4.74% of the yearly heating energy consumption compared with the reference wall. The optimization described can provide useful information and guidance for the energy saving of intermittently heated buildings.

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