Paper Conference

Proceedings of BSA Conference 2019: Fourth Conference of IBPSA-Italy


Numerical and experimental characterization of the thermal behavior of Complex Fenestrations Systems under dynamic conditions

Ingrid Demanega, Giuseppe De Michele, Martin Hauer, Stefano Avesani, Giovanni Pernigotto, Andrea Gasparella

Abstract: Complex Fenestration Systems (CFS) with different types of shading devices are widely used to enhance the building envelope’s energy efficiency and the occupants’ visual and thermal comfort. These technologies are characterized, among other features, by advanced shading systems, with for example complex geometries and highly reflective surfaces, which introduce a performance dependence on the angle of incidence of solar radiation. This peculiarity has to be covered by adequate thermal and optical models. However, the current most widespread thermal models, based on the standard ISO 15099 and implemented in the main building energy simulation tools, have shown some restrictions in their applicability for CFS. In addition to this, professionals of the façade construction industry are interested in assessing the components’ critical temperatures and the performance of the fenestration system under real dynamic operating conditions and in representative extreme conditions. In this framework, this study has investigated a new modelling approach for the thermal characterization of CFS under dynamic conditions by comparing simulation results with in-situ measurements of a triple-glazed window with integrated commercial blinds installed at the Free University of Bozen-Bolzano, Italy. The numerical assessment of the thermal behaviour of CFS was based on CFD simulations with the separately computed effect of solar radiation. The experimental characterization was performed with several instruments, such as conventional heat flux plates and a temperature-controlled in-situ measurement device to determine the undisturbed, transient heat flux through transparent components. From the comparison, a good correspondence between numerical and experimental results emerged and both approaches appraised the inertial effect of the fenestration system on the solar heat gain. Finally, it was observed that accurate optical modelling, together with CFD simulation, made it possible to compute the solar absorption and its significant impact on the fluid flow in the cavity, the components’ temperatures and the solar gains.
Pages: 109 - 116