Experimental thermal and energy performance study of a solar facade prototype using honeycomb transparent insulation and selective absorber

abstract

English

Application of advanced materials in building facades could bring relevant energy savings. Successful development of new and innovative (solar) façade concepts as well as their practical implementation relies on both theoretical and experimental activities. For example preliminary designs could be supported by computer modelling and simulations. Such simulations save significant amount of time and resources during development of the general concept, assembly details or construction processes. However the simulations should be always verified by experiments, because the performance of building components is influenced in many random variables that are hard to predict or model. Presented study describes initial results of modelling and testing of prototypes of solar façade concept inbuilt into an opaque building envelope. The concept combines transparent insulations with spectrally selective layers and latent thermal energy storage. The original concept was conceived using wide range of computer simulations: from simple one-dimensional energy transfer modelling to advanced CFD simulations of the heat convection and radiation in air gaps within the structure of the façade concept. The simulations were followed by testing of several prototypes. Several different laboratory and in situ experiments have been performed so far to verify the accuracy of the simulations. Climate chamber testing investigates mainly the thermal and optical properties of the developed prototypes in controlled environment. Both steady-state and transient boundary conditions were applied during the climate chamber testing. The tests included guarded hot plate and heat flux methods used to measure heat transfer coefficients of the tested materials. Thermal conductivity of the transparent insulation was measured at both atmospheric pressure and at technical vacuum. In situ testing of the prototypes supports the climate chamber testing, as it provides data about performance in unstable and unpredictable weather conditions. Two full scale in situ tests were launched to provide real life data from different locations. Both utilize the twin box method: multiple prototypes are tested in pairs. Each prototype in any pair can serve as a stand-alone testing platform or they can be used in pairs for comparison of test results. The data acquired during the testing are used for updating of the simulation models in advanced building energy simulation tools. The research currently focuses on describing the influence of transparent insulations on the overall performance of the façade. The updated simulations will be the basis for new generation of prototypes.

Solar thermal system, Transparent insulation, Selective absorber, Experimental testing, Climate chamber

SLÁVIK, R.; ČEKON, M.; STRUHALA, K.; ČURPEK, J.; JURÁŠ, P.

24. 1. 2018

ne-xt facades – Adaptive Facade Network

Munich

78

79

2

http://tu1403.eu/wp-content/uploads/COST-Next_proceeding_high_res.pdf