Effects of air temperature, humidity, and wind velocity distribution on indoor cooling load and outdoor human thermal environment at urban scale

2021 ◽  
pp. 111792
Author(s):  
Hideki Takebayashi
Keyword(s):  
Velocity Distribution ◽  
Wind Velocity ◽  
Air Temperature ◽  
Thermal Environment ◽  
Cooling Load

Urban heat risk assessment for pedestrians considering thermal environment and physiological change

2020 ◽  
Author(s):  
Ara Kim ◽  
Gayoung Yoo
Keyword(s):  
Heart Rate ◽  
Relative Humidity ◽  
Thermal Comfort ◽  
Wind Velocity ◽  
Air Temperature ◽  
Rate Increase ◽  
Thermal Environment ◽  
Heart Rate Increase ◽  
Urban Heat ◽  
Heat Risk

<p>As citizens face increasing heat risk due to climate change with urban heat island effect, heat risk assessments in urban have been conducted focusing on thermal diseases related to heatwave of vulnerable people. Although they provided a basis to establish adaptation strategies such as cooling centers, they could not consider citizens’ daily thermal comfort of diverse groups. Thermal comfort could be a part of heat risk because associated with work performance such as productive capacity as well as health. In particular, pedestrians’ thermal comfort can represent daily heat risk of outdoor urban environment. The past studies of pedestrians’ thermal comfort were evaluated using PMV (Predicted Mean Vote), an index based on temperature, wind velocity, relative humidity and a fixed number of metabolic rate depending on the subject’s activity level. The PMV ranges from -3 to +3 and higher value indicates higher discomfortable. Including metabolic factor, PMV did not actually consider an individuals’ physiological response (IPR) such as heart rate, skin temperature, etc. To overcome PMV’s limitation, IPR should be considered together with climatic factors when assessing pedestrians’ thermal comfort. Therefore, we aim to develop a new function of thermal comfort by incorporating PMV and IPR, especially heart rate, with validation using personal perception of thermal comfort based on survey. We selected a route of 500m length in Suwon, South Korea and 9 volunteer pedestrians walked the selected route 8 times at 2-4 pm. The walk experiment was repeated for 4 days. During the experiment, air temperature, relative humidity, and wind velocity were monitored using portable meteorological sensors. The real-time heart rate of each pedestrian was recorded using wearable sensor (Mi-band3). After every day walk, we asked each pedestrian 10 questions regarding satisfaction of thermal environment, perceived temperature, etc. The average value of PMV was 2.99 belonging to very discomfort category. Although heart rate increased with the length of exposure time to heat, the heart rate over time did not consistently increase with air temperature. It was probably because our temperature range (31.9℃- 35.2℃) during the experiment was not large enough and heart rate was influenced by other factors such as wind velocity. In the survey, 50% of volunteer pedestrians responded ‘discomfort’ and the others answered ‘slightly discomfort’. Comparing the survey (discomfort and slightly discomfort) with PMV (very discomfort), PMV generally overestimated. thermal comfort. We will categorize thermal comfort level according to heart rate increase between walking activity in outdoor and indoor. Here, the higher heart rate increase than average increase level indicates worse individual thermal comfort condition. This individual thermal comfort effect can modify the existing calculation of thermal comfort using air temperature, wind velocity, and humidity by adding modification factor of individual heart rate response (Ex. Thermal comfort=weighting factor(0.189*air temperature-0.775*wind velocity+0.195*relative humidity)). The final thermal comfort will be calculated based on the function and examined the precision of function through comparative analysis with the personal thermal perception of survey. As heart rate is an individual variable, we expect our function can be a tool evaluating the personalized heat risk.</p>

scholarly journals Assessment of PM1 number concentration with respect to traffic flow and thermal environment in a residential underground garage

2018 ◽  
Vol 20 (2) ◽  
pp. 304-315
Keyword(s):  
Traffic Flow ◽  
Wind Velocity ◽  
Air Temperature ◽  
Thermal Environment ◽  
Environmental Parameters ◽  
Number Concentration ◽  
Outdoor Environment ◽  
Pollution Levels ◽  
A Value ◽  
Partial Correlations

Particles with aerodynamic diameters < 1 μm (PM1) damage human health more severely than do coarse particles. In this study, PM1 number concentration, traffic flow, temperature and relative humidity in both a residential underground garage and at the entrance/exit, wind velocity at the entrance/exit were measured between May and June 2012 in Harbin, China. Pearson and partial correlations were employed to quantify the relationship between PM1 number concentration, traffic flow, and the thermal environment. The results show that mean PM1 number concentration in the garage during the measurement was 21,905 particles cm−3, which was approximately 1.54 times higher than the outdoor environment. Mean traffic flow, with a value of 0.2 vehicles min−1, may be the most important factor impacting PM1 pollution levels in the garage. The effects of air temperature inside the garage and wind velocity at the entrance/exit on PM1 pollution may be stronger compared with other environmental parameters. An inverse relationship between air temperature and PM1 number concentration was observed and decrease in wind velocity at the entrance/exit resulted in increased PM1 number concentration. This study provides fundamental reference data for PM1 number concentration levels in a residential underground garage.

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.

Experimental Modeling of Air Temperature and Velocity Distribution in an Engine Compartment

2006 ◽  
Author(s):  
A. A. Mozafari ◽  
M. H. Saidi ◽  
J. Neyestani ◽  
A. E. Sany
Keyword(s):  
Heat Transfer ◽  
Velocity Distribution ◽  
Air Temperature ◽  
Gasoline Engine ◽  
Point Of View ◽  
Vehicle Body ◽  
Air Distribution ◽  
Wind Effect ◽  
Engine Compartment ◽  
Air Velocity

Investigation of air distribution and wind effect on a vehicle body from the point of view of underhood heat transfer effect and proper positioning of vehicle elements such cooler, condenser and engine configuration is an important area for engine researchers and manufacturers as well. In this research, the effect of air velocity distribution and wind effect around a vehicle is simulated and temperature and velocity distribution around engine block which is influenced by the wind effect is investigated. Thermal investigation of the engine compartment components is performed using results of underhood air temperature and velocity distribution. The heat transfer from engine surface is calculated from the engine energy balance in which their input data are obtained from a comprehensive experimental study on a four cylinder gasoline engine.

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.

scholarly journals THE INFLUENCE OF THE CHANGES IN WIND VELOCITY ON THE OUTER HEAT EXCHANGE OF THE BUILDINGS

2021 ◽  
pp. 148-155
Author(s):  
D.V. Tarasevych ◽  
◽  
O.V. Bogdan ◽  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchange ◽  
Transfer Coefficient ◽  
Heat Loss ◽  
Wind Velocity ◽  
Air Temperature ◽  
Outer Surface ◽  
Climatic Parameters ◽  
The Heat Transfer Coefficient

When choosing architectural and planning solutions, such climatic factors as air temperature and humidity, having scalar quantities, as well as solar radiation, wind and precipitation having vector characteristics, must be taken into account. The calculated climatic parameters for the design of building enclosing structures, heat loss calculations and heat supply regulation are provided in the current documentation on norms and standards. The practical exploitation of various buildings demonstrates that in terms of initial climatic data, the choice of design parameters is not always efficiently justified; hence, the influence of the environment on the heating regime of the structures is insufficient in the estimations and sometimes erroneous. The wind is one of such climatic parameters. Its velocity and repeatability impact the heat exchange of the building structure with the environment as well as the alteration in temperature regime. The wind current towards the building creates additional pressure on the facade of the construction from the wind side direction. This leads, firstly, to air infiltration via the enclosing structures, and secondly, to the rise of heat exchange from the outer surface of the wall on the windward side. Based on estimated and analytical research, the values of the change in wind velocity depending on the altitude were analyzed, and its influence on the heat loss during heating of multi-storey buildings was assessed. The alterations in the wind velocity depending on the altitude were analyzed in the conditions of dense (urban) and broad construction. Besides, the authors presented the dependence of the convective component of the heat transfer coefficient of the outer surface of the structure on the values of the wind velocity. Based on the performed and presented calculations, it can be noticed that the heat transfer of the external structure will be much higher for multi-storey buildings than for mid-rise constructions. Thus, the convective component of the heat transfer coefficient of the outer surface rises by 36 % when the wind velocity increases from 5 m/s to 7 m/s. If not taking into consideration this dependence in the design, it can significantly influence the estimation of heat loss and energy efficiency of buildings, especially when it is about the increased percentage of facades glazing. The authors of the article assessed the heat loss for heating the windward and leeward facades at average values of the outside air temperature during the heating season in Ukraine. Hence, for constructions higher than 70 m with a calculated wind velocity of 5 m/s, heat losses increase from 10 % to 19 %. Such great difference in heat loss between the windward and leeward walls of the building requires increased thermal protection from the prevailing winter winds. Therefore, when designing multi-storey buildings, it is necessary to take into account changes in wind velocity according to the altitude. The obtained results can be useful both for choosing architectural and planning solutions, like the materials for external enclosing structures and for the objective assessment of the wind protection degree of individual buildings and territories.

scholarly journals An Interactive Task Conditioning System Featuring Personal Comfort Models and Non-Intrusive Sensing Techniques: A Field Study in Shanghai

Technologies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 90
Author(s):  
Siliang Lu ◽  
Erica Cochran Hameen
Keyword(s):  
Thermal Comfort ◽  
Field Study ◽  
Air Temperature ◽  
Indoor Air ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
New Paradigm ◽  
Dynamic Task ◽  
Current Task ◽  
Open Plan

Heating, ventilation and air-conditioning (HVAC) systems play a key role in shaping office environments. However, open-plan office buildings nowadays are also faced with problems like unnecessary energy waste and an unsatisfactory shared indoor thermal environment. Therefore, it is significant to develop a new paradigm of an HVAC system framework so that everyone could work under their preferred thermal environment and the system can achieve higher energy efficiency such as task ambient conditioning system (TAC). However, current task conditioning systems are not responsive to personal thermal comfort dynamically. Hence, this research aims to develop a dynamic task conditioning system featuring personal thermal comfort models with machine learning and the wireless non-intrusive sensing system. In order to evaluate the proposed task conditioning system performance, a field study was conducted in a shared office space in Shanghai from July to August. As a result, personal thermal comfort models with indoor air temperature, relative humidity and cheek (side face) skin temperature have better performances than baseline models with indoor air temperature only. Moreover, compared to personal thermal satisfaction predictions, 90% of subjects have better performances in thermal sensation predictions. Therefore, personal thermal comfort models could be further implemented into the task conditioning control of TAC systems.

XX.—On a See-Saw of Barometric Pressure, Temperature, and Wind Velocity between the Weddell Sea and the Ross Sea

1915 ◽  
Vol 35 ◽  
pp. 203-216
Author(s):  
R. C. Mossman
Keyword(s):  
South America ◽  
Wind Velocity ◽  
Air Temperature ◽  
Ross Sea ◽  
Barometric Pressure ◽  
Meteorological Conditions ◽  
Weddell Sea ◽  
The Other ◽  
The Subject ◽  
The One

In the course of a large inquiry on the inter-relations between the meteorological conditions in Antarctica and the Southern Ocean, on the one hand, and those prevailing in the southern continents, more especially South America, on the other, there has come to light an interesting see-saw between the barometric pressure, air temperature, and wind velocity in the Weddell and the Boss Seas. The above inquiry, which I hope to lay before this Society shortly, refers to the eight-year period 1902–09; and since the present paper deals with the years 1902, 1903, 1911, and 1912, I have thought it better to make it the subject of a separate communication. The positions of these stations and others where observations have been made are shown on the accompanying map, for which I am indebted to Dr H. R. Mill. The figures within the rings give the number of years covered by the records at the various places.

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