scholarly journals Thermal performance of a non–segmented and segmented tall atrium in hot and humid climate

2021 ◽  
Vol 2042 (1) ◽  
pp. 012162
Author(s):  
Priya Pawar ◽  
Deying Zhang ◽  
Xiaoying Wu ◽  
Werner Lang
Keyword(s):  
Wind Velocity ◽  
Air Temperature ◽  
Indoor Air ◽  
Thermal Conditions ◽  
Wind Pressure ◽  
Humid Climate ◽  
Pressure Coefficients ◽  
Starting Point ◽  
Buoyancy Forces ◽  
Hot And Humid Climate

Abstract The study was designed to quantify the thermal conditions in tall atria in office buildings to serve as a starting point towards understanding their performance. The simulation study of a non-segmented and segmented atrium of 250 m height reveals indoor air temperature, wind velocity contours and wind pressure coefficients at various heights of each atrium type. In a hot and humid climate like that of Singapore, the internal temperatures within each atrium stack remain constant at 27°C. However, the wind velocity in the non-segmented atrium (of 0.5 - 0.7 m/s) is lower than acceptable (0.9 m/s) for human occupancy. Adding segments and a larger inlet to the atrium solves the problem of low wind velocity without increasing the effective ambient temperature within the atrium stack. Additionally, the segmented atrium offers the advantage of displaying lower buoyancy forces by lowering the pressure differential within a tall stack thereby providing better comfort conditions.

Influence of Glazing Types on the Indoor Thermal Performance of Tropical High-Rise Residential Buildings

2016 ◽  
Vol 692 ◽  
pp. 27-37
Author(s):  
Nedhal Al-Tamimi ◽  
Abdultawab Qahtan
Keyword(s):  
Air Temperature ◽  
Indoor Air ◽  
Residential Buildings ◽  
Primary Objective ◽  
Radiation Absorption ◽  
Base Case ◽  
Indoor Environments ◽  
Humid Climate ◽  
High Rise ◽  
Hot And Humid Climate

In tropical climates, the solar radiation absorption of glazed windows results in overheated indoor environments and increased cooling energy loads during daytime. Meanwhile, situations differ during nighttime. The present study focuses on the effects of glazing type on the indoor temperature in high-rise residential buildings in the hot and humid climate of Malaysia. The primary objective of this study is to assess the effects of six glazing types on the indoor air temperature of the base case room oriented toward the southwest with a Window Wall Ratio WWR of 45% under both ventilated and unventilated conditions. The effects during daytime and nighttime are investigated separately. A computerized simulation tool (Virtual Environment by Integrated Environmental Solutions) is used to conduct the investigation. Penang is selected as the empirical background location of a hot and humid climate. The study found that reflective double glazing exhibits lower indoor air temperature throughout the day regardless of the ventilation condition, with an optimum improvement of up to 107% and 14% in unventilated and ventilated rooms, respectively, compared with single clear glazing. The study recommends the use of reflective single or double glass in regions with a hot and humid climate similar to that of Malaysia.

scholarly journals Mitigation Strategies for Overheating and High Carbon Dioxide Concentration within Institutional Buildings: A Case Study in Toronto, Canada

Buildings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 124 ◽  
Author(s):  
Claire Tam ◽  
Yuqing Zhao ◽  
Zaiyi Liao ◽  
Lian Zhao
Keyword(s):  
Carbon Dioxide ◽  
Air Quality ◽  
Indoor Air Quality ◽  
Air Temperature ◽  
Indoor Air ◽  
Indoor Environment ◽  
Thermal Conditions ◽  
Co2 Concentration ◽  
Hvac System

Indoor air quality and thermal conditions are important considerations when designing indoor spaces to ensure occupant health, satisfaction, and productivity. Carbon dioxide (CO2) concentration and indoor air temperature are two measurable parameters to assess air quality and thermal conditions within a space. Occupants are progressively affected by the indoor environment as the time spent indoors prolongs. Specifically, there is an interest in carrying out investigations on the indoor environment through surveying existing Heating, Ventilation, Air Conditioning (HVAC) system operations in classrooms. Indoor air temperature and CO2 concentration in multiple lecture halls in Toronto, Canada were monitored; observations consistently show high indoor air temperature (overheating) and high CO2 concentration. One classroom is chosen as a representative case study for this paper. The results verify a strong correlation between the number of occupants and the increase in air temperature and CO2 concentration. Building Energy Simulation (BES) is used to investigate the causes of discomfort in the classroom, and to identify methods for regulating the temperature and CO2 concentration. This paper proposes retro-commissioning strategies that could be implemented in institutional buildings; specifically, the increase of outdoor airflow rate and the addition of occupancy-based pre-active HVAC system control. The proposed retrofit cases reduce the measured overheating in the classrooms by 2-3 °C (indoor temperature should be below 23 °C) and maintain CO2 concentration under 900 ppm (the CO2 threshold is 1000 ppm), showing promising improvements to a classroom’s thermal condition and indoor air quality.

scholarly journals Portland versus alkali-activated cement wall panels containing mine tailing as aggregate: one-story house thermal performance simulation in a Brazilian and Portuguese hot and humid climate

2019 ◽  
Vol 274 ◽  
pp. 03003
Author(s):  
Miriam O. Baumbach ◽  
Lucas T. S. Ramos ◽  
Raquel P. Batista ◽  
Raquel D. Oliveira ◽  
Paulo H. R. Borges
Keyword(s):  
Portland Cement ◽  
Carbon Dioxide Emissions ◽  
Thermal Conditions ◽  
Mining Activities ◽  
Humid Climate ◽  
Adaptive Comfort ◽  
Wall Panels ◽  
Hot And Humid Climate ◽  
Belo Horizonte ◽  
Alkali Activated

Alkali-activated materials (AAM) compared to Portland cement (PC) may significantly reduce the carbon dioxide emissions, as well as the consumption of non-renewable natural resources in civil engineering applications. Further environmental advantages are possible if natural aggregates used for mortars and concretes are replaced with residues and wastes from industrial or mining activities. This paper compares the performance of PC with AAM as binders in cementitious wall panels for external cladding in hot and humid climate. Three different cementitious matrices are proposed, consisting of either 100% Portland cement (PC), 100% alkali-activated metakaolin (MK) or 80/20 alkali-activated Metakaolin/Blastfurnace slag (80/20 MK/BFS). Mortars were produced with the addition of tailing from iron-ore mining activities in the state of Minas Gerais, Brazil, at an aggregate to binder ratio of 1.0 for all matrices. The thermal property determined for the three mortars was Thermal Conductivity using a heat flow meter (HFM) apparatus according to ISO 8301 (1999); their apparent density was also measured. After that, one-story house building simulation was carried out using the Energy Plus Software. The main room annual operative temperature provided by different panels used as cladding was compared to the adaptive comfort range established on ASHRAE Standard 55/2013 for a Brazilian and Portuguese hot and humid climate. According to the Climate Zone Definitions of ANSI/ASHRAE Standard 169/2006, Belo Horizonte (Brazil) and Funchal (Portugal) were selected as a sample of 2A zone that presents a hot and humid climate. Partial results of this research were presented in this paper. Results show that building simulations can effectively contribute to validate the selection of materials in the production of sustainable wall panels that provide suitable thermal conditions to the users in hot and humid climate.

Improving indoor air quality and thermal comfort by total heat exchanger for an office building in hot and humid climate

2014 ◽  
Vol 20 (7) ◽  
pp. 731-737 ◽  
Author(s):  
Fu-Jen Wang ◽  
Meng-Chieh Lee ◽  
Tong-Bou Chang ◽  
Yong-Sheng Chen ◽  
Ron-Chin Jung
Keyword(s):  
Heat Exchanger ◽  
Air Quality ◽  
Thermal Comfort ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Total Heat ◽  
Office Building ◽  
Humid Climate ◽  
Hot And Humid Climate

scholarly journals Indoor Daylighting and Thermal Response of a Passive Solar Building to Selective Components of Solar Radiation

Buildings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 34
Author(s):  
Ochuko Kelvin Overen ◽  
Edson Leroy Meyer ◽  
Golden Makaka
Keyword(s):  
Relative Humidity ◽  
Solar Radiation ◽  
Air Temperature ◽  
Indoor Air ◽  
Temperature Response ◽  
Longwave Radiation ◽  
Thermal Conditions ◽  
Visible Radiation ◽  
Downward Longwave Radiation ◽  
Passive Solar

Solar radiation provides the most significant natural energy in buildings for space heating and daylighting. Due to atmospheric interference, solar radiation received at the Earth’s surface consists of direct beam and diffuse radiation, where diffuse can be further broken down into longwave and visible radiation. Although each of these components co-occurs, their influence on the indoor visual and thermal conditions of a building differ. This study aims to analyze the influence of the various components of solar radiation on the indoor thermal and daylighting of a passive solar building. Thus, a pyrheliometer, pyranometer, shaded-pyranometer, and pyrgeometer mounted on a SOLYS 2 (Kipp & Zonen, Delft, Netherlands) dual Axis sun tracker, were used to monitor direct, global horizontal, diffuse and downward longwave radiation, respectively. The seasonal indoor air temperature and relative humidity were measured using an HMP 60 temperature relative humidity probe. A Li-210R photometric sensor was used to monitor the indoor illuminance. The summer and winter indoor air temperature, as well as relative humidity, were found to be influenced by diffuse horizontal and global horizontal irradiance, respectively. In summer, the indoor air temperature response to diffuse horizontal irradiance was 0.7 °C/ħW/m2 and 1.1 °C/ħW/m2 to global horizontal irradiance in winter, where ħ is 99.9 W/m2. The indoor daylighting which was found to be above the minimum office visual task recommendation in most countries, but within the useful daylight illuminance range was dominated by direct normal irradiance. A response of 260 lux/ħW/m2 was observed. The findings of the study support the strategic locating of the windows in passive solar design. However, the results show that north-facing clerestory windows without shading device could lead to visual discomfort.

scholarly journals Indoor Thermal Performance of Ventilated Dwellings Using Fly Screens in the Hot-Humid Climate of Chennai, India

2009 ◽  
Vol 4 (2) ◽  
pp. 150-157 ◽  
Author(s):  
Vijayalaxmi J ◽  
S.P Sekar
Keyword(s):  
Solar Radiation ◽  
Air Temperature ◽  
Thermal Performance ◽  
Indoor Air ◽  
Tropical Climate ◽  
Summer Period ◽  
Humid Climate ◽  
Floor Area ◽  
Hot Humid Climate ◽  
Heating Up

In a hot-humid tropical climate, indoor thermal performance can be enhanced by comfort ventilation. Indoor ventilation depends upon building opening size. But risks involved in providing openings include ingress of mosquitoes and insects which thrive in the tropical climate. A practical and prevalent option to prevent insects in ventilated dwellings of the tropical, hot-humid city of Chennai, India is through the use of fly screens. Fly screens, when used over openings, prevent a certain quantum of solar radiation and wind from entering inside the rooms. Reduced direct solar radiation prevents the indoors from heating up, while reduced wind movement prevents the cross ventilation. Therefore, it is important to know the indoor thermal performance of ventilated rooms in the presence of fly screens with changing opening sizes. The criterion to evaluate indoor thermal performance in this paper is indoor air temperature. The aim of this research is to investigate the influence of fly screens on openings with varying sizes, in a naturally ventilated dwelling in the hot-humid climate of Chennai, India, during the summer period. The results of the study show that fly screens raise the indoor air temperature when openings are in the range of 100% to 35% of the room floor area. There is no significant change in the indoor air temperature when the opening sizes are less than 30% of the room floor area.

Wind flow on and around U-shaped buildings

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Tugba Inan Gunaydin
Keyword(s):  
Wind Velocity ◽  
Negative Pressure ◽  
Incidence Angle ◽  
Wind Pressure ◽  
Positive Pressure ◽  
Content Type ◽  
Pressure Coefficients ◽  
Building Shape ◽  
Reentrant Corner ◽  
Pressure Distributions

Purpose This paper presents the numerical examination of wind pressure distributions on U-plan shaped buildings having four different depth ratios (DR) as 0.5, 1, 2 and 4 over wind incidence angle (WIA) of 0°. The purpose of this study is to investigate the effect of irregular building form, DRs, distances from the reentrant corner, wind velocity values on and around wind pressure distributions of the buildings. With this aim, ANSYS Fluent 20.0 Computational Fluid Dynamics (CFD) program is used for the analysis. Design/methodology/approach Four U-shaped buildings having the same height, width and wing length but having different DR in plan were analyzed by the application of CFD package of ANSYS 20. With this purpose, wind pressure distributions on and around U-plan shaped buildings were analyzed for the wind velocity values of 2 and 5 m/s over WIA of 0°. Comprehensive results were obtained from the analyses. Findings While the change in the DR values did not create a significant change in positive pressure coefficients on A and E surfaces, negative pressure values increased as the DR decreased. The negative pressure coefficients observed on the A and E surfaces become higher than the positive pressure coefficients with the decrease in the DR. On contrary to that condition, with the decrease in the DR, G surfaces take higher positive pressure coefficients than the negative pressure coefficients. The reason for this is that the DR decreases and negative pressure values on G surface significantly decrease. The effect of the DR on the pressure coefficients is remarkable on B and D surfaces. The negative pressure coefficients on the B and D surfaces tend to increase as the DR decreases. Research limitations/implications This study focused on DRs and wind velocity values effect on pressure coefficients to limit variables. Different building wing dimensions did not take into account. Originality/value Although there are a number of studies related to wind behavior of irregular plan shaped buildings, irregular building forms have not been extensively investigated parametrically, especially in terms of the effect of DR on wind pressures. This study is therefore designed to fill this gap by analyzing impacts of various parameters like building shape with various DRs, WIA and wind velocity values on wind pressure distributions and velocity distributions on and around the building.

scholarly journals Thermal Comfort Evaluation Using Linear Discriminant Analysis (LDA) and Artificial Neural Networks (ANNs)

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 538
Author(s):  
Katarzyna Gładyszewska-Fiedoruk ◽  
Maria Jolanta Sulewska
Keyword(s):  
Thermal Comfort ◽  
Air Temperature ◽  
Indoor Air ◽  
Thermal Conditions ◽  
Climatic Conditions ◽  
Test Results ◽  
Linear Discriminant ◽  
Comfort Evaluation ◽  
Questionnaire Surveys ◽  
Radiant Temperature

The thermal sensations of people differ from each other, even if they are in the same thermal conditions. The research was carried out in a didactic teaching room located in the building of the Faculty of Civil and Environmental Engineering in Poland. Tests on the temperature were carried out simultaneously with questionnaire surveys. The purpose of the survey was to define sensations regarding the thermal comfort of people in the same room, in different conditions of internal and external temperatures. In total 333 questionnaires were analyzed. After the discriminant and neural analyses it was found that it is not possible to forecast the thermal comfort assessment in the room based on the analyzed variables: gender, indoor air temperature, external wall radiant temperature, and outdoor air temperature. The thermal comfort assessments of men and women were similar and overlapped. The results of this study confirm that under the same thermal conditions about 85% of respondents assess thermal comfort as good, and about 15% of respondents assess thermal comfort as bad. The test results presented in this article are similar to the results of tests carried out by other authors in other climatic conditions.

scholarly journals Effects of Thermal Mass, Window Size, and Night-Time Ventilation on Peak Indoor Air Temperature in the Warm-Humid Climate of Ghana

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
S. Amos-Abanyie ◽  
F. O. Akuffo ◽  
V. Kutin-Sanwu
Keyword(s):  
Simulation Model ◽  
Air Temperature ◽  
Indoor Air ◽  
Window Size ◽  
Simulation Software ◽  
Maximum Temperature ◽  
Thermal Mass ◽  
Mass Window ◽  
Humid Climate ◽  
Night Time

Most office buildings in the warm-humid sub-Saharan countries experience high cooling load because of the predominant use of sandcrete blocks which are of low thermal mass in construction and extensive use of glazing. Relatively, low night-time temperatures are not harnessed in cooling buildings because office openings remain closed after work hours. An optimization was performed through a sensitivity analysis-based simulation, using the Energy Plus (E+) simulation software to assess the effects of thermal mass, window size, and night ventilation on peak indoor air temperature (PIAT). An experimental system was designed based on the features of the most promising simulation model, constructed and monitored, and the experimental data used to validate the simulation model. The results show that an optimization of thermal mass and window size coupled with activation of night-time ventilation provides a synergistic effect to obtain reduced peak indoor air temperature. An expression that predicts, indoor maximum temperature has been derived for models of various thermal masses.

scholarly journals Temperate Air Breathing Increases Cycling Performance in Hot and Humid Climate Environment

Life ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 911
Author(s):  
Clovis Chabert ◽  
Aurélie Collado ◽  
Olivier Hue
Keyword(s):  
Air Temperature ◽  
Cycling Performance ◽  
Humid Climate ◽  
Constant Intensity ◽  
Male Athletes ◽  
Perceived Effort ◽  
Sports Events ◽  
Hot Air ◽  
Air Temperatures ◽  
Hot And Humid Climate

Practicing physical activity in a hot and humid climate (HHC) is becoming increasingly common due to anthropogenic climate change and the growing number of international sports events held in warm countries. The aim of this study was to understand the physiological and psychological effects of breathing two air temperatures during cycling exercise in HHC. Ten male athletes performed two sessions of exercise in HHC (T°: 32.0 ± 0.5 °C, relative humidity: 78.6 ± 0.7%) during which they breathed hot air (HA, 33.2 ± 0.06 °C) or temperate air (TA, 22.6 ± 0.1 °C). Each session was composed of 30 min of pre-fatigue cycling at constant intensity, followed by a 10 min self-regulated performance. During pre-fatigue, TA induced a better feeling score and a lower rating of perceived effort (respectively, +0.9 ± 0.2, p < 0.05; 1.13 ± 0.21; p < 0.05) with no changes in physiological parameters. During performance, oxygen consumption and mechanical workload were increased by TA (respectively, +0.23 ± 0.1 L min−1, p < 0.05 and +19.2 ± 6.1 W, p < 0.01), whereas no significant differences were observed for psychological parameters. Reducing the breathed air temperature decreased the discomfort induced by HHC during exercise and increased the performance capacity during self-regulated exercise. Thus, breathed air temperature perception is linked to the hardship of training sessions and directly contributes to the performance decrease in HHC.

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