scholarly journals Solar Heat Gain Reduction of Ventilated Double Skin Windows without a Shading Device

2017 ◽  
Vol 10 (2) ◽  
pp. 64 ◽  
Author(s):  
Bokyoung Koo ◽  
Keonho Lee ◽  
Youngsub An ◽  
Kyudong Lee

Author(s):  
Tran Ngoc Chan ◽  
Pham Thi Hai Ha ◽  
Pham Van Luong ◽  
Nguyen Thi Khanh Phuong

The research discusses calibration of the method used to calculate solar heat transfer through shaded windows with continuous vertical slanted shading devices (below is abbreviated as "vertical slanted fins") with any slant angle Θ through a radiation reduction coefficient - Kbt. In order to evaluate the reduction of solar heat on window surface shaded by shading devices, a designated coefficient β of solar heat gain reduction through glazed windows should be established. It is the ratio of the transmitted amount of solar heat (including direct and diffuse radiation) through windows with shading device QK to those without solar shading device QKo. The study also introduces two in-house software programs. These programs help calculating solar heat gain and coefficient β for vertically slanted fins with any slant angle θ for 16 window orientations. The results of this study will be applied to the implementation of the Vietnamese national code QCVN 09:2017/BXD towards energy efficiency in buildings.



2020 ◽  
Vol 38 (3A) ◽  
pp. 402-411
Author(s):  
Mohannad R. Ghanim ◽  
Sabah T. Ahmed

Double skin ventilated roof is one of the important passive cooling techniques to reduce solar heat gain through roofs. In this research, an experimental study was performed to investigate the thermal behaviour of a double skin roof model. The model was made of two parallel galvanized steel plates. Galvanized steel has been used in the roof construction of industrial buildings and storehouses in Iraq. The effect of inclination angle (ϴ) from the horizontal and the spacing (S) between the plates was investigated at different radiation intensities. It is found that using a double skin roof arrangement with a sufficient air gap (S) can reduce the heat gain significantly. The higher the inclination angle (ϴ) the higher the ventilation rate, the lower the heat gain through the roof. In this study, increasing the air gap from 2 cm to 4 cm reduced the heat gain significantly but when the gap was further increased to 6 cm, the reduction in the heat flux was insignificant. A dimensionless correlation was also reduced between Nusselt number () and the single parameter  where L is the channel length. This correlation can be handily utilized for designing of engineering applications dealing with high temperature difference natural convection heat transfer.





2016 ◽  
Vol 9 (4) ◽  
pp. 399-409 ◽  
Author(s):  
Guoqing He ◽  
Jianfeng Xu ◽  
Yun Zheng ◽  
Sanming Zhang ◽  
Qi’an Bai




2021 ◽  
Vol 881 (1) ◽  
pp. 012048
Author(s):  
Abdul Hakim Abdul Majid ◽  
Azhar Ghazali

Abstract One of the most efficient methods to optimize thermal performance in a building is the practical design of the façade. The double skin façade‘(DSF) is a crucial decision for handling the interaction between outdoor and indoor spaces. It also offers some spatial diversity in the design process. Recently, a lot of focus has been paid to it instead of the more traditionally glazed curtain wall. This is because of its potential to reduce energy effectively, achieve thermal comfort in the building, and save costs. The indoor spaces near to the glazed facades will become warm due to high incidence solar radiation on the East-West facades in Malaysia’s tropical environment. In the tropics, one of the solar heat gain reduction approaches is the use of double skin-facade (DSF). One of the fundamental components of the double-skin facade is the blinds. Blinds located in the cavity of the double-skinned facade and buffer the building from solar heat gain or perform the role of a pre-heater for ventilation air. In general, the temperature of the blinds is high, which is helpful in the cold period but problematic in the hot period. To minimize the cooling loads of the building, technological innovations for the shading system are considered. Plants can dissipate absorbed solar radiation into resistant and latent heat. Plants turn radiation into the latent heat. This paper aims to study the effectiveness of a double skin façade and explore improved innovative design for a double-skin façade design integrated with vertical green on research building to optimize thermal performance. This paper will collect data of the thermal performance of double skin façade, precedent study and run simulation analysis to achieve the aim of the paper.





2021 ◽  
Vol 9 (10) ◽  
pp. 1368-1378
Author(s):  
Hodo-Abalo Samah ◽  
◽  
Magolmeena Banna ◽  
Belkacem Zeghmati ◽  
◽  
...  

Planted roofs are passive cooling techniques that reduce the thermal load of buildings. In this paper, a Dynamic mathematical model based ontime average Navier-Stokes equationsfor a plantedroof in hothumidclimates has beendeveloped for evaluating the cooling potential.Transfer equations are solved using a finite difference scheme and Thomas algorithm. The model was applied for the simulation of a planted roof in Togolese climate conditions. Results showed that, evapotranspiration and Solar Heat gain Factor are functions of the Leaf Area Index LAI which is the most important parameter when considering the foliage material. For LAI equal to 6, latent heat peak value reaches 900 W.m-2while that of sensible heat is around 350 W.m-2. Solar heat gain factor can bereducedto 15% fortheplantedroofagainst 45% forbareroof. It is clearly proved that the foliage density and hence the vegetation canopy type selection greatly influence the thermal efficiency of the bioclimatic insulation screen. A larger Leaf Area Index reduces the solar flux penetration and increases evapotranspiration which is an important parameter when considering surrounding microclimate formation.



Sign in / Sign up

Export Citation Format

Share Document