Design Range of Indoor Relative Humidity in Radiant Cooling Environment

2011 ◽  
Vol 243-249 ◽  
pp. 4905-4908
Author(s):  
Xue Min Sui ◽  
Xu Zhang ◽  
Guang Hui Han
Keyword(s):  
Relative Humidity ◽  
Thermal Comfort ◽  
Mean Radiant Temperature ◽  
Design Standards ◽  
Human Thermal Comfort ◽  
Radiant Cooling ◽  
Climate Parameter ◽  
Radiant Temperature ◽  
Thermal Comfort Model ◽  
The Impact

Relative humidity is an important micro-climate parameter in radiant cooling environment. Based on the human thermal comfort model, this paper studied the effect on PMV index of relative humidity, and studied the relationship of low mean radiant temperature and relative humidity, drew the appropriate design range of indoor relative humidity for radiant cooling systems.The results show that high relative humidity can compensate for the impact on thermal comfort of low mean radiant temperature, on the premise of achieving the same thermal comfort requirements. However, because of the limited compensation range of relative humidity, together with the constraints for it due to anti-condensation of radiant terminal devices, the design range of relative humidity should not be improved, and it can still use the traditional air-conditioning design standards.

Thermal comfort analysis of radiant cooling panels with dedicated fresh-air system

2020 ◽  
pp. 1420326X2096114
Author(s):  
S. Y. Qin ◽  
X. Cui ◽  
C. Yang ◽  
L. W. Jin
Keyword(s):  
Relative Humidity ◽  
Surface Temperature ◽  
Thermal Comfort ◽  
Air Temperature ◽  
Indoor Air ◽  
Area Ratio ◽  
Human Thermal Comfort ◽  
Air Supply ◽  
Radiant Cooling ◽  
Air System

Radiant system has been increasingly applied in buildings due to its good thermal comfort and energy-saving potential. In this research, a simplified predicted mean vote (PMV) model and sensible cooling load equation were proposed based on human thermal comfort. Simulations were carried out using Airpak to explore relationships among thermal comfort characteristics, design and operation parameters. Results show that radiant surface temperature, fresh-air supply temperature and the area ratio are correlated approximately linearly with the indoor air temperature, while the relative humidity has little effect on the indoor air temperature. The indoor air velocity in the simulated environment was no more than 0.15 m/s, satisfying the requirements of limit values in the occupied zone. The results indicate that the optimum radiant surface temperature ( tc) is 19°C to 23°C when fresh-air supply temperature ( ts) is 26°C. The relative humidity ( φ) should be maintained at 50% to 70%, and the area ratio of radiant panels to total surfaces ( k1) should be kept within 0.15 to 0.38 when the radiant surface temperature is 20°C and the fresh-air supply temperature is 26°C. The simplified PMV model and the sensible load equation can provide reference for panel design based on characteristics of radiant cooling panels with a dedicated fresh-air system.

scholarly journals Calculating human thermal comfort and thermal stress in the PALM model system 6.0

2020 ◽  
Vol 13 (7) ◽  
pp. 3055-3065 ◽  
Author(s):  
Dominik Fröhlich ◽  
Andreas Matzarakis
Keyword(s):  
Thermal Comfort ◽  
City Planning ◽  
Urban Climate ◽  
Climate Index ◽  
Mean Radiant Temperature ◽  
Thermal Indices ◽  
Large Eddy Simulation Model ◽  
Human Thermal Comfort ◽  
Model Based ◽  
Radiant Temperature

Abstract. In the frame of the project “MOSAIK – Model-based city planning and application in climate change”, a German-wide research project within the call “Urban Climate Under Change” ([UC]2) funded by the German Federal Ministry of Education and Research (BMBF), a biometeorology module was implemented into the Parallelized Large-Eddy Simulation Model (PALM) system. The new biometeorology module is comprised of methods for the calculation of UV-exposure quantities, a human–biometeorologically weighted mean radiant temperature (Tmrt), as well as for the estimation of human thermal comfort or stress. The latter is achieved through the implementation of the three widely used thermal indices: perceived temperature (PT), Universal Thermal Climate Index (UTCI), as well as physiologically equivalent temperature (PET). Comparison calculations were performed for the PT, UTCI and PET indices based on the SkyHelios model and showing PALM calculates higher values in general. This is mostly due to a higher radiational gain leading to higher values of mean radiant temperature. For a more direct comparison, the PT, PET and UTCI indices were calculated by the biometeorology module, as well as the programs provided by the attachment to Verein Deutscher Ingenieure (VDI) guideline 3787, as well as by the RayMan model based on the very same input dataset. Results show deviations below the relevant precision of 0.1 K for PET and UTCI and some deviations of up to 2.683 K for PT caused by repeated unfavorable rounding in very rare cases (0.027 %).

Thermomodernization of the school and change of the level of thermal comfort

2021 ◽  
pp. 62-74
Author(s):  
V. Deshko ◽  
◽  
N. Buyak ◽  
I. Bilous ◽  
◽  
...  
Keyword(s):  
Energy Consumption ◽  
Thermal Comfort ◽  
Comfort Level ◽  
Mean Radiant Temperature ◽  
Before And After ◽  
Change In The Mean ◽  
The Mean ◽  
Energy Audits ◽  
Radiant Temperature ◽  
The Impact

The paper highlights the topical issue of ensuring the appropriate thermal comfort level and reducing energy consumption by public buildings. Thermal modernization, in turn, allows increasing the level of thermal comfort, which is not taken into account and evaluated in practice, although the relevant standards for comfort conditions and categories of buildings to ensure comfort have been introduced in Ukraine. The aim of the study is to analyze the impact of thermal modernization on the level of energy consumption and thermal comfort. The paper analyzes the change in the level of comfort before and after thermal modernization, defines the comfortable conditions category of the building, presents the change in the mean radiant temperature, as one of the main factors of PMV change in these conditions. PMV has been found to vary from -0.7 in the cold months to 0.2 in the off-season. Changing the thermal resistance can increase the PMV. The wall of the S orientation is characterized by larger fluctuations of PMV, which is due to the inflow of solar radiation and as a consequence of increasing the mean room radiant temperature. The change in the value of energy consumption is analyzed, the class of energy efficiency and the category for providing comfortable conditions are determined. Such an approach on the example of a real building is an example for conducting energy audits and certification taking into account comfort indicators.

scholarly journals A Study Regarding the Thermal Environment and Thermal Comfort during the 2021 National Intercollegiate Athletic Games and Related Activities in Taiwan

2021 ◽  
Vol 8 (1) ◽  
pp. 32
Author(s):  
Si-Yu Yu ◽  
Andreas Matzarakis ◽  
Tzu-Ping Lin
Keyword(s):  
Thermal Comfort ◽  
Thermal Environment ◽  
Extreme Weather Events ◽  
Intercollegiate Athletic ◽  
Outdoor Sports ◽  
Human Thermal Comfort ◽  
Knowledge Platform ◽  
Globe Temperature ◽  
Radiant Temperature ◽  
The Impact

Due to the impact of global warming and extreme weather events, outdoor human thermal comfort conditions become tougher and harder to mitigate, especially for pedestrian movement and exercises. In order to better understand the thermal environment and thermal comfort, especially for outdoor sports, the 2021 National Intercollegiate Athletic Games held in Tainan, southern Taiwan, in May was selected as the research target. Both on-site, real-time environmental monitoring data and the Taiwan Climate Change Projection Information and Adaptation Knowledge Platform (TCCIP)’s Taiwan ReAnalysis Downscaling data (TReAD) were applied to estimate the modified physiologically equivalent temperature (mPET), the mean radiant temperature (Tmrt), and the wet bulb globe temperature (WBGT) for members participating in the relevant activities. The focus of this study was to analyze the thermal performance of (1) the torch relay around Taiwan from 20 April to 8 May and (2) the scheduled planning games held at the track and field stadium, at the National Cheng Kung University (NCKU), Taiwan, from May 15 to May 18, 2021.

scholarly journals Field Assessment of Neighboring Building and Tree Shading Effects on the 3D Radiant Environment and Human Thermal Comfort in Summer within Urban Settlements in Northeast China

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Jing Du ◽  
Lin Liu ◽  
Xin Chen ◽  
Jing Liu
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Short Wave ◽  
Radiant Flux ◽  
View Factor ◽  
Mean Radiant Temperature ◽  
Human Thermal Comfort ◽  
Long Wave ◽  
Shading Effects ◽  
Radiant Temperature

Shading is one of the most effective strategies to mitigate urban local-scale heat stress during summer. Therefore, this study investigates the effects of shading caused by buildings and trees via exhaustive field measurement research on urban outdoor 3D radiant environment and human thermal comfort. We analyzed the characteristics of micrometeorology and human thermal comfort at shaded areas, and compared the difference between building and tree shading effects as well as that between shaded and sunlit sites. The results demonstrate that mean radiant temperature Tmrt (mean reduction values of 28.1°C for tree shading and 28.8°C for building shading) decreased considerably more than air temperature Ta (mean reduction values of 1.9°C for tree shading and 1.2°C for building shading) owing to shading; furthermore, the reduction effect of shading on UTCI synthesized the variation in the above two parameters. Within the shaded areas, short-wave radiant components (mean standardized values of 0.104 for tree shading and 0.087 for building shading) decreased considerably more than long-wave radiant components (mean standardized values of 0.848 for tree shading and 0.851 for building shading) owing to shading; the proportion of long-wave radiant flux densities absorbed by the reference standing person was high, leading to a relatively high long-wave mean radiant temperature, and R2 between long-wave mean radiant temperature and air temperature exceeded 0.8. Moreover, the directional sky view factor (SVF) was utilized in this study, and it showed significant positive correlation with short-wave radiant flux densities, but no statistically evident correlation with long-wave radiant flux densities. Meanwhile, Tmrt was most relevant with SVFS⟶ with R2 of 0.9756. Furthermore, UTCI rose two categories at the sunlit areas compared with that at the shaded areas. In contrast, Ta and Tmrt played the first positive role in UTCI at shaded and sunlit areas, respectively.

scholarly journals Calculating human thermal comfort and thermal stress in the PALM model system 6.0

2019 ◽  
Author(s):  
Dominik Fröhlich ◽  
Andreas Matzarakis
Keyword(s):  
Thermal Comfort ◽  
City Planning ◽  
Model System ◽  
Climate Index ◽  
Mean Radiant Temperature ◽  
Clothing Insulation ◽  
Human Thermal Comfort ◽  
Model Based ◽  
Perceived Temperature ◽  
Radiant Temperature

Abstract. In the frame of the project MOSAIK – Model–based city planning and application in climate change, a German-wide research project within the call Urban Climate Under Change ([UC]2) funded by the German Federal Ministry of Education and Research (BMBF), a biometeorology module was implemented into the PALM model system. The new biometeorology module comprises of methods for the calculation of uv-exposure quantities, a human–biometeorologically weighted mean radiant temperature (Tmrt), as well as for the estimation of human thermal comfort or stress. The latter is achieved through the implementation of the three widely–used thermal indices Perceived Temperature (PT), Universal Thermal Climate Index (UTCI), as well as Physiologically Equivalent Temperature (PET) together with a newly developed instationary index instationary Perceived Temperature (iPT) based on PT for use with the multi–agent model. Comparison calculations were performed for the indices PT, UTCI and PET based on the SkyHelios model and showing PALM calculates higher values in general. This is mostly due to a higher radiational gain leading to higher values of mean radiant temperature. For a more direct comparison, the indices PT, PET and UTCI were calculated by the biometeorology module, as well as the programs provided by the attachment to the VDI guideline 3787, as well as by the RayMan model based on the very same input dataset. Results show deviations below rounding precision (less than 0.1 K) for PET and UTCI and some deviations of up to 2.683 K for PT caused by rounding leading to the selection of a different clothing insulation step in very rare cases (0.027 %).

scholarly journals Membrane-assisted radiant cooling for expanding thermal comfort zones globally without air conditioning

2020 ◽  
Vol 117 (35) ◽  
pp. 21162-21169 ◽  
Author(s):  
Eric Teitelbaum ◽  
Kian Wee Chen ◽  
Dorit Aviv ◽  
Kipp Bradford ◽  
Lea Ruefenacht ◽  
...  
Keyword(s):  
Water Supply ◽  
Thermal Comfort ◽  
Cooling System ◽  
Thermal Sensation ◽  
Dew Point ◽  
Mean Radiant Temperature ◽  
Radiation Exchange ◽  
Radiant Cooling ◽  
Chilled Water ◽  
Radiant Temperature

We present results of a radiant cooling system that made the hot and humid tropical climate of Singapore feel cool and comfortable. Thermal radiation exchange between occupants and surfaces in the built environment can augment thermal comfort. The lack of widespread commercial adoption of radiant-cooling technologies is due to two widely held views: 1) The low temperature required for radiant cooling in humid environments will form condensation; and 2) cold surfaces will still cool adjacent air via convection, limiting overall radiant-cooling effectiveness. This work directly challenges these views and provides proof-of-concept solutions examined for a transient thermal-comfort scenario. We constructed a demonstrative outdoor radiant-cooling pavilion in Singapore that used an infrared-transparent, low-density polyethylene membrane to provide radiant cooling at temperatures below the dew point. Test subjects who experienced the pavilion (n= 37) reported a “satisfactory” thermal sensation 79% of the time, despite experiencing 29.6 ± 0.9 °C air at 66.5 ± 5% relative humidity and with low air movement of 0.26 ± 0.18 m⋅s−1. Comfort was achieved with a coincident mean radiant temperature of 23.9 ± 0.8 °C, requiring a chilled water-supply temperature of 17.0 ± 1.8 °C. The pavilion operated successfully without any observed condensation on exposed surfaces, despite an observed dew-point temperature of 23.7 ± 0.7 °C. The coldest conditions observed without condensation used a chilled water-supply temperature 12.7 °C below the dew point, which resulted in a mean radiant temperature 3.6 °C below the dew point.

scholarly journals Influence of Subjective and Objective Thermal Comfort Parameters on Building Primary Fuel Energy Consumption

2018 ◽  
Vol 7 (4.3) ◽  
pp. 383 ◽  
Author(s):  
V. I. Deshko ◽  
N. A. Buyak ◽  
I. O. Sukhodub1
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Heating System ◽  
Energy System ◽  
Regression Equations ◽  
Heating Source ◽  
Human Thermal Comfort ◽  
Building Energy System ◽  
Radiant Temperature ◽  
Thermal Comfort Model

The building is considered together with a heating source in the analysis, it is also proposed to include a human thermal comfort model in this complex system. Regression equations for determining the comfortable room air temperature according to energy and exergy approaches are presented. Human thermal comfort model is included for the first time in the complex building energy system, by determining the comfortable room air temperature, which corresponds to PMV (predicted mean vote), not lower than value for the corresponding building category. The effect of enclosing structures thermal resistance changes on space average radiant temperature and on building category in terms of providing comfortable conditions is estimated. The influence of thermal comfort subjective parameters on primary fuel exergy consumption by the centralized heating system is estimated on the basis of developed model for the Ukrainian conditions.  

An Assessment of Thermal Comfort for Thermoelectric-Based Radiant Cooling Systems: A Numerical Investigation

2021 ◽  
Author(s):  
Mohadeseh Seyednezhad ◽  
Hamidreza Najafi
Keyword(s):  
Thermal Comfort ◽  
Test Chamber ◽  
Comfort Level ◽  
Dew Point ◽  
Mean Radiant Temperature ◽  
Spherical Object ◽  
Cooling Systems ◽  
Modeling And Analysis ◽  
Radiant Cooling ◽  
Radiant Temperature

Abstract Studying various innovative cooling/heating technologies as alternatives to vapor-compression refrigeration cycles has received growing attention over the last few years. Thermoelectric (TE) systems are among the promising emerging technologies in this category. In the present paper, numerical modeling and analysis is performed using COMSOL Multiphysics to assess the performance of a thermoelectric (TE)-based radiant cooling ceiling panel on the thermal comfort in a test chamber. The system consists of a rectangular test chamber (∼ 1.2 m × 1.2 m × 1.5 m) with a ceiling panel fabricated on the center of the ceiling (0.6 m × 0.6 m × 0.002 m). Four TE modules are installed on the backside of the ceiling panel producing a cooling effect to maintain the ceiling temperature at the desired level. The lowered temperature of the ceiling panel allows heat exchange through radiation and convection. A spherical object is used to model a globe thermometer (GT) and capture the mean radiant temperature inside of the chamber. The variation of mean radiant temperature and operative temperature versus time are assessed under natural convection, and the comfort level is evaluated using the PMV method based on ASHRAE Standard 55. Design challenges, such as temperature limitation to the dew point temperature, among others, will be discussed. The result of this study provides insights regarding the expected thermal comfort from TE-based radiant cooling systems under various conditions.

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