scholarly journals Influence of Traditional and Solar Reflective Coatings on the Heat Transfer of Building Roofs in Mexico

2021 ◽  
Author(s):  
Iván Hernández-Pérez
Keyword(s):  
Concrete Slab ◽  
Weather Data ◽  
Control Case ◽  
Computational Tool ◽  
Warm Climate ◽  
Heat Gain ◽  
Exterior Surface ◽  
Building Components ◽  
Reflective Coatings ◽  
Volume Method

Building roofs are sources of unwanted heat for buildings situated in zones with a warm climate. Thus, reflective coatings have emerged as an alternative to reject a significant fraction of solar energy received by roofs. In this research, the thermal behavior of concrete slab-type roofs with traditional and solar reflective coatings was simulated using a computational tool. Weather data from four cities in Mexico with a warm climate were used as boundary conditions. This tool is an in-house code based on the Finite Volume Method developed by the author to perform building components simulations. The code was validated with experimental data from previous work. A series of comparative simulations were developed, taking a gray roof as a control case. The results showed that for the roof without thermal insulation (single roof), the solar reflective coatings reduced the exterior surface between 11 and 16∘C. Consequently, the single roofs’ daily heat gain was reduced by a factor ranging between 41 and 54%. On the other hand, for the insulated roof, the reflective coatings reduced the exterior surface temperature between 17 and 21∘C. At the same time, the daily heat gain of composite roofs was reduced between 37 and 56%.

scholarly journals Influence of Traditional and Solar Reflective Coatings on the Heat Transfer of Building Roofs in Mexico

2021 ◽  
Vol 11 (7) ◽  
pp. 3263
Author(s):  
Iván Hernández-Pérez
Keyword(s):  
Surface Temperature ◽  
Concrete Slab ◽  
Weather Data ◽  
Control Case ◽  
Computational Tool ◽  
Warm Climate ◽  
Heat Gain ◽  
Exterior Surface ◽  
Insulation Thickness ◽  
Reflective Coatings

Building roofs are sources of unwanted heat for buildings situated in zones with a warm climate. Thus, reflective coatings have emerged as an alternative to reject a fraction of the solar energy received by roofs. In this research, the thermal behavior of concrete slab roofs with traditional and solar reflective coatings was simulated using a computational tool. The studied slab configurations belong to two groups, non-insulated and insulated roofs. In the second group, the thermal insulation thickness complies with the value recommended by a national building energy standard. Weather data from four cities in Mexico with a warm climate were used as boundary conditions for the exterior surface of the roofs. The computational tool consisted of a numerical model based on the finite volume method, which was validated with experimental data. A series of comparative simulations was developed, taking a gray roof as the control case. The results demonstrated that white roofs without insulation had an exterior surface temperature between 11 and 16 °C lower than the gray roof without insulation. Thus, the daily heat gain of these white roofs was reduced by a factor ranging between 41 and 54%. On the other hand, white roofs with insulation reduced the exterior surface temperature between 17 and 21 °C compared to the gray roof with insulation. This temperature reduction caused insulated white roofs to have a daily heat gain between 37 and 56% smaller than the control case. Another contribution of this research is the assessment of two retrofitting techniques when they are applied at once. In other words, a comparison between a non-insulated gray roof and an insulated white roof revealed that the latter roof had a daily heat gain up to 6.4-times smaller than the first.

Effect of Heat-Reflective Insulation Coating of Building Energy Saving in Summer

2013 ◽  
Vol 427-429 ◽  
pp. 368-371
Author(s):  
Chao He ◽  
Yang Wang ◽  
Yi Bin Chen ◽  
Teruyuki Fukuhara
Keyword(s):  
Energy Saving ◽  
Electricity Consumption ◽  
Building Energy ◽  
Heat Gain ◽  
Air Conditioning System ◽  
Exterior Surface ◽  
Insulation Coating ◽  
Building Energy Saving ◽  
Saving Effect ◽  
Reflective Coatings

In order to discuss the effect of energy saving of heat-reflective insulation coating on exterior walls of building, the wall temperature change of two test rooms with heat insulation or not in Hangzhou has been monitored in summer, and the heat flux data of east, south and west walls were analyzed. The results indicate that the reflective coatings reduce the exterior surface temperature by up to 7 to 8°C. The reduction in heat gain of east, south and west walls is significant, which is the cooling effect. The total surface heat gain of exterior walls without reflective coatings is 2.44 times larger than those without them. In particular, the heat gain of walls with reflective coatings is nearly 5.27 times more than that of walls without reflective coatings. The reduction in electricity consumption of air-conditioning system in the building with reflective coatings is 2.5KWh/m2 per month by calculation, which well proves the energy saving effect of reflective coatings.

Variation of Structural Capacity of Reinforced Concrete Slab Due to the Repeated Cyclic Loading Idealized for Thermal Load

2010 ◽  
Vol 452-453 ◽  
pp. 697-700
Author(s):  
Soo Yeon Seo ◽  
Seung Joe Yoon ◽  
Hyun Do Yoon
Keyword(s):  
Cyclic Loading ◽  
Concrete Slab ◽  
Weather Data ◽  
Effect Of Temperature ◽  
Reinforced Concrete Slab ◽  
Structural Capacity ◽  
Long Term Effect ◽  
Test Parameters ◽  
Rc Slabs

A variation of temperature by sunlight acting on a RC roof slab causes a change of stress in concrete since it expands during summer and is compressed during winter. This behavior repeats annually and affects structural capacity of member for both serviceability and ultimate level. In this paper, a variation of cyclic temperature loading is calculated by analyzing the weather data of Korea for 20 years. In addition, an experimental work is planned to find the long term effect of temperature change. Four RC slabs are made with same dimension. Test parameters are loading duration (10, 20, 30 years). Observation of stiffness variations according to cyclic loading duration shows that the serious stiffness drop happens after 10 year's cyclic loading at summer while after 30 year's loading at winter. From the failure test, maximum strength of specimen that experienced repeated preloading was approximately 12% less than standard specimen without any repeated preloading.

scholarly journals The effects of microclimate and time resolution of meteorological data on hygrothermal analysis of wood frame building facades

2021 ◽  
Author(s):  
Wai Ki Wu
Keyword(s):  
Meteorological Data ◽  
Weather Data ◽  
Climate Data ◽  
Frame Building ◽  
Hourly Data ◽  
Average Water ◽  
Building Components ◽  
Wood Frame ◽  
Hygrothermal Analysis ◽  
The Impact

When performing hygrothermal analysis for building envelopes, climate data is required as boundary conditions. This study investigates the effect of the microclimatic conditions using Toronto Pearson Airport and downtown hourly data. The results showed that the average water content of the wood frame building façade were similar throughout the study period. The high moisture content peaks reduced to average within days. The arithmetic averaged hourly weather data may also affect the analysis’ results. 5-minute weather data is collected from the Ryerson weather network. The hourly data is constructed from the 5-minute data by arithmetic averaging. The simulation results from both dataset followed closely to each other throughout the study period. The averaging of hourly data removed some details form the raw meteorological data. However, it does not affect the overall trend of the climate condition and the impact to the hygrothermal analysis of building components is very limited.

scholarly journals Measurement of Flat Slab Deformations by the Multi-Image Photogrammetry Method

2017 ◽  
Vol 25 (4) ◽  
pp. 19-25 ◽  
Author(s):  
Marián Marčiš ◽  
Marek Fraštia ◽  
Tomáš Augustín
Keyword(s):  
Image Processing ◽  
Concrete Slab ◽  
Measurement Techniques ◽  
3D Measurement ◽  
Flat Slab ◽  
The World ◽  
Photogrammetric Method ◽  
Load Tests ◽  
Building Components ◽  
Photogrammetric Measurement

Abstract The use of photogrammetry during load tests of building components is a common practise all over the world. It is very effective thanks to its contactless approach, 3D measurement, fast data collection, and partial or full automation of image processing; it can deliver very accurate results. Multi-image convergent photogrammetry supported by artificial coded targets is the most accurate photogrammetric method when the targets are detected in an image with a higher degree of accuracy than a 0.1 pixel. It is possible to achieve an accuracy of 0.03 mm for all the points measured on the object observed if the camera is close enough to the object, and the positions of the camera and the number of shots are precisely planned. This contribution deals with the design of a special hanging frame for a DSLR camera used during the photogrammetric measurement of the deformation of flat concrete slab. The results of the photogrammetric measurements are compared to the results from traditional contact measurement techniques during load tests.

scholarly journals The effects of microclimate and time resolution of meteorological data on hygrothermal analysis of wood frame building facades

2021 ◽  
Author(s):  
Wai Ki Wu
Keyword(s):  
Meteorological Data ◽  
Weather Data ◽  
Climate Data ◽  
Frame Building ◽  
Hourly Data ◽  
Average Water ◽  
Building Components ◽  
Wood Frame ◽  
Hygrothermal Analysis ◽  
The Impact

When performing hygrothermal analysis for building envelopes, climate data is required as boundary conditions. This study investigates the effect of the microclimatic conditions using Toronto Pearson Airport and downtown hourly data. The results showed that the average water content of the wood frame building façade were similar throughout the study period. The high moisture content peaks reduced to average within days. The arithmetic averaged hourly weather data may also affect the analysis’ results. 5-minute weather data is collected from the Ryerson weather network. The hourly data is constructed from the 5-minute data by arithmetic averaging. The simulation results from both dataset followed closely to each other throughout the study period. The averaging of hourly data removed some details form the raw meteorological data. However, it does not affect the overall trend of the climate condition and the impact to the hygrothermal analysis of building components is very limited.

scholarly journals Numerical parametric study of a cooling system for an LNG storage tank

2019 ◽  
Vol 74 ◽  
pp. 21 ◽  
Author(s):  
Mohamed Haddar ◽  
Moez Hammami ◽  
Mounir Baccar
Keyword(s):  
Heat Transfer ◽  
Lateral Surface ◽  
Storage Tank ◽  
Cooling System ◽  
Liquefied Natural Gas ◽  
Cylindrical Tank ◽  
Heat Gain ◽  
Nusselt Numbers ◽  
Numerical Parametric Study ◽  
Volume Method

The study of the cooling system of a Liquefied Natural Gas (LNG) storage tank is vital for the safety of the installation. The objective of this paper is to develop cooling baffles capable of reducing the heat gain from the environment leading to a loss of LNG quantity, keeping the Boil-Off Gas (BOG) under control. For this purpose, a specific code based on the finite volume method was developed to improve our knowledge of the hydrodynamic and thermal behaviors of LNG in the cylindrical tank. In addition, the effect of the number, position and dimension of the baffles on the flow structure of LNG were determined. The obtained results indicated that the location of the baffles at the top of the tank nearby the vicinity of the wall would yield a better cooling of the LNG. Moreover, we emphasized that a number of six baffles would give rise to a better heat transfer. For a design purpose, the Nusselt numbers on the lateral surface and on the baffles have been correlated as functions of Rayleigh and baffle numbers.

Analysis on the Energy-Saving Property of Solar Heat Reflective Coatings on Building in Beijing

2014 ◽  
Vol 787 ◽  
pp. 159-163 ◽  
Author(s):  
Qian Jin Mao ◽  
Qiu Rui Lv ◽  
Ya Li Wang ◽  
Xiao Yu Ma ◽  
Rui Wang ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Energy Saving ◽  
Building Envelope ◽  
Heat Gain ◽  
Reflective Coating ◽  
South Wall ◽  
The Common ◽  
North Wall ◽  
Saving Effect ◽  
Reflective Coatings

To discuss the effect of energy saving of heat-reflective coating on building, the heat gain of exterior building envelope in summer and winter in Beijing has been calculated. The results indicated that the higher the reflectivity of coating, the better the energy saving effect. The energy consumption of roof and different direction walls were analyzed. The energy saving effect on roof is the best, however the effect is not obvious on the east and west walls. The heat reflective coating has no effect on north wall but exhibits effect on south wall. The energy saving effect of brick red heat-reflective coating is not obvious compared with the common brick red coating.

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