Renewable Energy Global Innovations features: Solar radiation properties of common membrane roofs used in building structures

Significance Statement

Researchers from Tianjin University in China proposed to test the solar radiation properties of membrane roofs with different materials, colors, thickness values, and printing dot ratios. The research work is now published in peer-reviewed journal, Material and Design.

Membrane roofs are widely used building materials, and their solar radiation coefficients significantly affect the thermal environment of the steel structures. According to the authors solar radiation properties, affect the indoor thermal environment of buildings and the temperature of steel structures below the roof.

The research team focused on five types of membranes that are commonly used in building roofs and they studied their solar radiation coefficients. These membranes include ethylene tetrafluoroethylene ETFE, polytetrafluoroethylene PTFE, polyvinyl chloride PVC with polyvinylidene fluoride PVDF coating, thermoplastic olefin TPO, and polyethylene PE. To consider the effect of thickness, printing silver dot ratio, and surface color, the researcher selected 25 membrane specimens. A numerical simulation method using a CFD package was also presented to analyze the temperature of steel members under membrane roofs. The effect of ambient wind and the incubator effect, were observed under four conditions with different enclosing degrees.

They found the difference between steel plate temperature and ambient temperature increases with the solar radiation transmittance of a membrane roof. Moreover, the higher the transmittance of the membrane roofs the more solar radiation absorbed by the steel plate. Professor Hongbo Liu who is the first author in the published paper said that the temperature of the steel plates below the membrane roofs is higher than ambient air temperature under solar radiation, especially the fully enclosed condition. From the team findings, the temperature of the steel plates below the membrane roofs are higher compared to when exposing it to solar radiation.

The solar radiation transmittance of the ETFE membrane without printing dots and the PE membrane according to the team was found to be higher than that of the other types of membranes. The solar radiation transmittance of the PTFE and PVDF membranes is lower while that of the TPO membrane is lowest.

The research team also confirmed the printing dot in the ETFE membrane to have a weak solar radiation transmittance but strong reflectance and absorbance. Furthermore, they confirmed the temperature of the steel structures to be below the PTFE, PVDF, and TPO membrane roofs and over 41.2 °C during summer, which is at least 7.2 °C higher than ambient air temperature.

This study successfully tested the solar radiation properties of membrane roofs with different materials, colors, thickness values, and printing dot ratios and the research team was able to achieve their aim of detecting the properties of membrane roofs under different condition.     

About The Author

Dr. Hongbo Liu, an associate professor of the School of Civil Engineering, Tianjin University, who has acquired the honor of “the national excellent doctoral dissertations”. He has directed more than 10 research subjects related to “the non-uniform temperature effect on large span spatial structures under solar radiation” and also published more than 100 academic papers, in which over 40 papers are included in SCI database.  

About The Author

Dr. Zhihua Chen, a Professor of Structural Engineering in the School of Civil Engineering at Tianjin University in China, has received the “state council special allowance”. He is also the national candidate of the “New Century National Hundred, Thousand and Ten Thousand Talent Project”. Dr. Chen has directed over 100 engineering research projects of steel structures and spatial structures, and published over 300 research papers, of which nearly 100 papers belong to the Science Citation Index category. His research contribution has received 1 “Second level award of National Technology Progress Award” and 7 “First level award of Provincial or Ministry Technology Progress Award”.  

Journal Reference

Hongbo Liu¹, Bo Li¹, Zhihua Chen¹ ,Ting Zhou², Qi Zhang², Solar Radiation Properties of Common Membrane Roofs used in Building Structures, Materials and Design 105 (2016) 268–277.

Show Affiliations

1. State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China
2. School of Architecture, Tianjin University, Tianjin 300072, China

 

 

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