Comparison of Building Simulation Methods for Modeling Apartment Balconies

The purpose of this study is to compare the load calculation results by a model using the air changes per hour (ACH) method and a model using an airflow network (AFN) and to ascertain what causes the difference between the two models. In the basic case study, the difference in the heat transfer distribution of the model in the interior space was investigated. The most significant difference between the two models is the heat transfer that results from infiltration. Parameter analysis was performed to investigate the relationship between the difference and the environmental variables. The result shows that the greater the difference is between the air temperature inside the balcony and the outdoor air temperature, and the greater the air flows from the balcony to the residential area, and the greater the heating and cooling load difference occurs. The analysis using the actual weather files of five domestic cities in South Korea rather than a virtual case shows that the differences are not so obvious when the wind blows at a constant speed throughout the year, but are dominant when the wind does not blow during the night and is stronger alongside the occurrence of sunlight during the day.

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Buildings

10.1093/oso/9780198802297.003.0003 ◽

2017 ◽

Author(s):

Peter Rez

Keyword(s):

Heat Transfer ◽

Heat Pump ◽

Energy Efficient ◽

Energy Use ◽

Fossil Fuel ◽

Local Climate ◽

Heating And Cooling ◽

The Difference ◽

As If

Most of the energy used by buildings goes into heating and cooling. For small buildings, such as houses, heat transfer by conduction through the sides is as much as, if not greater than, the heat transfer from air exchanges with the outside. For large buildings, such as offices and factories, the greater volume-to-surface ratio means that air exchanges are more significant. Lights, people and equipment can make significant contributions. Since the energy used depends on the difference in temperature between the inside and the outside, local climate is the most important factor that determines energy use. If heating is required, it is usually more efficient to use a heat pump than to directly burn a fossil fuel. Using diffuse daylight is always more energy efficient than lighting up a room with artificial lights, although this will set a limit on the size of buildings.

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Air versus water temperature of aquatic habitats in Delhi: Implications for transmission dynamics of Aedes aegypti

Geospatial health ◽

10.4081/gh.2018.707 ◽

2018 ◽

Vol 13 (2) ◽

Cited By ~ 2

Author(s):

Gaurav Kumar ◽

Veena Pande ◽

Shweta Pasi ◽

Vijay P. Ojha ◽

Ramesh C. Dhiman

Keyword(s):

Water Temperature ◽

Air Temperature ◽

Data Loggers ◽

Breeding Habitats ◽

Significant Difference ◽

The Difference ◽

Near Future ◽

Plastic Containers ◽

Local Weather ◽

Container Material

The present study was planned to characterize the microclimate experienced by Aedes larvae in different breeding habitats by determining the temperature variations in water kept in containers during different months under natural conditions. The study was conducted in three municipal zones of Delhi. In each site, four types of container material (plastic, cement, iron and ceramic) were chosen for recording the water temperature in the containers. Daily air and water temperatures (mean, maximum and minimum values) recorded by HOBO and Tidbit data loggers, respectively, were compared using analysis of variance and Tukey’s honest significant difference (HSD) tests. Mean monthly temperature of water varied from 16.9 to 33.0 °C in tin containers, 17.3 to 35.6°C in plastic containers, 14.3 to 28.5°C in ceramic pots, 23.3 to 30.4°C in cemented underground tanks (UGT) and 15.8 to 35.1°C in cemented overhead tanks (OHTs). Corresponding values for the air temperature ranged from 17.7 to 36.1°C. The difference between temperature of water in the containers and air temperature was highest for ceramic pots. Daily mean, maximum and minimum temperatures recorded by different data loggers differed significantly (P<0.05). When Tukey HSD test was applied for data analysis, the daily mean air temperature differed significantly from the water temperature in tin and ceramic pots as well as cemented OHTs. The temperature of water in the different breeding habitats investigated was lower than the air temperature. Moreover, actual air temperature as recorded by HOBO was higher than the temperature recorded by local weather stations. Considering the ongoing climate change, cemented UGT and earthen pots may be more productive breeding habitats for the Aedes mosquito in the near future, while plastic and cemented OHTs might no longer be suitable for Aedes breeding.

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Estimation of sensible and latent heat based on measurements for non-typical large room

E3S Web of Conferences ◽

10.1051/e3sconf/201911600085 ◽

2019 ◽

Vol 116 ◽

pp. 00085

Author(s):

Sylwia Szczęśniak ◽

Juliusz Walaszczyk

Keyword(s):

Latent Heat ◽

Air Temperature ◽

Historical Data ◽

Operation Mode ◽

Ventilation System ◽

Thermal Conditions ◽

Existing Building ◽

Heating And Cooling ◽

Air Temperatures ◽

Heating And Cooling Load

The knowledge about dynamic changing heating and cooling load in existing building is essential for proper energy management. Whenever existing building is analyzed or ventilation system is going optimized, it’s essential to estimate temporary sensible and latent heat based on historical data. The basic conditions for heat calculations are quasi-stable thermal conditions. If supply air temperature significantly varies in short time, what happens very often, the calculations can give untrue results. The procedure described in this article improves usability of measured data affected by rapid supply air temperature changing. Therefore real sensible and latent heat can be calculated, what it is important for future optimization process. Specified, on the basis of varying supply and exhaust air temperatures, thermal loads range from -55.8 kW to 40.7 kW was substitute to more authentic range from -14.1 kW to 51.2 kW received from the conducted simulations. In addition, the data obtained from the simulation showed that latent heat gains were associated with the air temperature in the room, and not with the operation mode of the ventilation unit (day/night) as observed on the basis of historical data.

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Modeling of Heat Transfer in a Moving Packed Bed: Case of the Preheater in Nickel Carbonyl Process

Journal of Applied Mechanics ◽

10.1115/1.1991862 ◽

2005 ◽

Vol 73 (1) ◽

pp. 47-53 ◽

Cited By ~ 17

Author(s):

Redhouane Henda ◽

Daniel J. Falcioni

Keyword(s):

Heat Transfer ◽

Packed Bed ◽

Outer Wall ◽

Volume Averaging ◽

Equation Model ◽

Operating Conditions ◽

Design Parameters ◽

Gas Phases ◽

Calculation Results ◽

The Difference

Heat transfer in a two-dimensional moving packed bed consisting of pellets surrounded by a gaseous atmosphere is numerically investigated. The governing equations are formulated based on the volume averaging method. A two-equation model, representing the solid and gas phases separately, and a one-equation model, representing both the solid and gas phases, are considered. The models take the form of partial differential equations with a set of boundary conditions, some of which were determined experimentally, and design parameters in addition to the operating conditions. We examine and discuss the parameters in order to reduce temperature differences from pellet to pellet. The calculation results show that by adopting a constant temperature along the preheater outer wall and decreasing the velocity of the pellets in the preheater, the difference in temperature from pellet to pellet is reduced from ∼120°C to ∼55°C, and the thermal efficiency of the preheater is tremendously improved.

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Ceiling mounted radiant panels – calculations of heat output in heating and cooling application

E3S Web of Conferences ◽

10.1051/e3sconf/20184400035 ◽

2018 ◽

Vol 44 ◽

pp. 00035

Author(s):

Lawrence Drojetzki ◽

Janusz Wojtkowiak

Keyword(s):

Heat Exchange ◽

Cooling Capacity ◽

Heat Output ◽

Heating And Cooling ◽

University Of Technology ◽

Technology Changes ◽

Calculation Results ◽

Surrounding Space ◽

The Difference ◽

Heating Mode

This paper describes calculations of heat exchange between a radiant heating and cooling ceiling panel and the surrounding space. The calculations were created on the basis of empirical equations published in literature and experimental research of radiant ceiling panels carried out at the Institute of Environmental Engineering of the Poznan University of Technology. Changes in heating or cooling output vs. air and panel surface temperature difference were investigated. Based on the calculation results, the influence of the colour, gloss and shape of the panels surface on the heating or cooling capacity was indicated. Performed calculations show that the proportion of radiation in the whole heat exchange for the matte black ceiling panel reach 50% for cooling and 75% for heating mode for the considered temperatures. Comparing two rectangular, square and circular panels with the same area, it has been shown that the shape of the surface affects the heat exchange due to the difference in convectional flows in the boundary layers for different cases. Possible explanations of the discrepancies between the theoretical model and experimental results were presented.

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Effectiveness of Active Debate Method in English Speaking Skills of Students in SMAN 3 Padangsidimpuan

Journal of English Teaching and Learning Issues ◽

10.21043/jetli.v2i2.5739 ◽

2019 ◽

Vol 2 (2) ◽

pp. 171

Author(s):

Khairunnisah Nasution ◽

Apriyanti Hasibuan ◽

Happy Sri Rezeki Purba

Keyword(s):

T Test ◽

Control Group ◽

Significance Level ◽

Significant Difference ◽

Calculation Results ◽

Active Debate ◽

English Speaking ◽

The Difference ◽

Experimental Group ◽

Speaking Skills

<em>This research aimed are : 1) Knowing the effectiveness of the debate method in improving students' speaking skills in learning English, 2) Knowing the differences in students' speaking skills using the debate method and without using debate method.The data was collected using test, they were pretest and postest. The result of evaluation was analyzed through quantitative. The results showed: There was a significant difference between the speaking skills of students who received speaking learning using the active debate method with students who received speaking learning without using the active debate method The difference in speaking skills is indicated by the results of the posttest t-test of the control group and the posttest of the experimental group, namely the calculation results show that the t count score is greater than the t table score (th: 2.882> tt: 1.994) at the 5% significance level and db 70. The results of the t-test showed that there were differences in the speaking skills of the control group students who received speaking learning without using the active debate method and the experimental group that received speaking learning using the active debate method.</em>

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Effect of Minimum Airflow Setting of VAV Unit on Building Energy Consumption under Korean Climatic Condition

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.450-451.1435 ◽

2012 ◽

Vol 450-451 ◽

pp. 1435-1439

Author(s):

Kwang Ho Lee ◽

Kyung Il Chin ◽

Jong Ho Yoon

Keyword(s):

Energy Consumption ◽

Air Temperature ◽

Variable Air Volume ◽

Unit System ◽

Energy Impact ◽

Heating And Cooling ◽

Significant Difference ◽

Gas Consumption ◽

Forced Air ◽

The Impact

Variable Air Volume (VAV) unit system is one of the commonly used forced-air heating and cooling systems in office buildings. It controls the airflow with the discharge air temperature fixed for cooling, while the discharge air temperature is adjusted with the airflow fixed at the minimum for heating. This study presents the simulation of conventional VAV unit system performance applied in the typical office building prototype. Each VAV unit has the minimum airflow setting for the ventilation purpose and its impact on the energy consumption is significant. The aim of this study is to evaluate the energy impact of the minimum airflow setting of VAV box using EnergyPlus ver. 6.0 software platform. The energy result breakdown of three model cases is discussed: minimum airflow fraction setting of 10%, 20% and 30%. As a result, the minimum airflow setting has significant impact on the reheat energy and thus the annual boiler gas consumption shows significant difference among each simulation case. Monthly heating energy profile is also discussed for the better understanding of the impact of different minimum fractions on the heating energy.

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The effect of high air temperature on pregnancy and birth weight in Merino sheep

Australian Journal of Agricultural Research ◽

10.1071/ar9560435 ◽

1956 ◽

Vol 7 (5) ◽

pp. 435 ◽

Cited By ~ 20

Author(s):

NTM Yeates

Keyword(s):

Birth Weight ◽

Low Birth Weight ◽

Air Temperature ◽

Atmospheric Temperature ◽

The Other ◽

Merino Sheep ◽

Significant Difference ◽

Higher Temperature ◽

The Difference ◽

Pregnancy And Birth

During the winter of 1954, 21 pregnant Peppin strain Merino ewes were subjected daily, 7 hours a day, 7 days a week, to an air temperature of 105°F dry-bulb, 92°F wet-bulb, in a psychrometric room. Nine of the ewes were heated from the date mating started and the other 12 from the 38th day of pregnancy. Birth weights of the lambs of the two groups showed no significant difference from those of 10 unheated control ewes pregnant during the same period. However, when subjected the following year, for the same period daily throughout the whole of pregnancy, to a higher temperature, namely, 112°F dry-bulb, 98°F wet-bulb, 10 experimental ewes produced lambs having a mean birth weight 1 lb 13 oz less than that of the lambs of eight unheated control ewes. The difference is highly significant statistically. It is concluded that pregnancy in Merinos is adversely affected by extremely high atmospheric temperature; and that this could well explain the low birth weight of lambs born following a summer gestation in tropical Queensland and in certain other parts of Australia when an unusually hot summer occurs.

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Estimating the Thermal Properties of the Cover and the Floor in a Plastic Greenhouse

Energies ◽

10.3390/en14071970 ◽

2021 ◽

Vol 14 (7) ◽

pp. 1970

Author(s):

Hyung-Kweon Kim ◽

Young-Sun Ryou ◽

Young-Hwa Kim ◽

Tae-Seok Lee ◽

Sung-Sik Oh ◽

...

Keyword(s):

Heat Transfer ◽

Heat Flux ◽

Air Temperature ◽

Average Method ◽

Weighted Average ◽

Balance Equations ◽

Total Heat Transfer ◽

Weighted Average Method ◽

U Value ◽

The Difference

This study comprehensively analyzed the heat loss and total heat transfer coefficient (U-value) of a single-span experimental plastic greenhouse covered with a double layer of 0.1 mm thick polyethylene. The air temperature and heat flux (W m−2) of the greenhouse components were measured from 18:00 to 06:00, and the energy balance equations under steady-state conditions were determined. The heat flux and U-value of the roof, sides, front and rear, and floor of the greenhouse were determined and compared. The results showed that these values for the roof play an important role in determining the heat load in the greenhouse, and that the average heat transfer through the floor is very small. The average U-value of the greenhouse cover is a comprehensive value which takes the U-values of the roof, sides, and front and rear into account through the use of an area–weighted average method. Finally, an average U-value of 3.69 W m−2 °C −1 was obtained through the analysis of the variations in the U-value, as it is related to the difference in air temperature between the interior and exterior of the greenhouse, as well as to the outdoor wind speed. The relationships between the average U-value and those of the roof, sides, and front and rear of the experimental greenhouse were modeled, and were shown to have a highly linear relationship.

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