A new method for the thermal characterization of transparent and semi-transparent materials using outdoor measurements and dynamic simulation

• A new method to evaluate U and SHGC of glazing in outdoor conditions is proposed.
• Short-term outdoor measurements and dynamic simulation are used in the method.
• SHGC of a light diffusing insulating glass is obtained with accuracy lower than 10%.

The work presents a new method to evaluate the thermal performance of transparent and semi-transparent materials under real operating conditions. The methodology could be particularly useful to test innovative materials and composites whose thermal properties are not known. It is easily reproducible, low cost, with a low technical impact. The proposed method uses experimental devices named “Solar Test Boxes” (STB) and a dynamic simulation software: IDA Indoor Climate and Energy. The outdoor measurements inside and outside the test boxes are used to accurately calibrate the dynamic simulation model of STB with the objective to obtain the global thermal transmittance (U) and Solar Heat Gain Coefficient (SHGC) of the test sample.The paper illustrates the methodology and the application of the method for the determination of the thermal characteristics of a light diffusing insulating glass. The application of the method to the case study allowed estimating SHGC with accuracy below ±10%. The U-value yields a poor result due to the lack of measurement range (required temperature difference) to assess this parameter.