The research of this thesis focuses on the stiffness and the durability of a composite panel that consists of thin glass as outer layers and a 3D printed core element from recycled PET. Thin Alumino-silicate glass, mostly used in computers, tablets and smartphones, is known for its lightweight, flexibility, durability, high bending strength and relatively low weight. However, the lack of stiffness allows for some safety-issues. In combination with another material, composite panel can be generated. The core element of this composite panel will consist of 3D printed recycled PET. The use of recycled PET has been taken into account, due to the increasing of plastic waste for the next 30 years. A combination of both materials allows for a much stiffer composite panel and reduction in weight of 71,9 % compared to a normal double glazed window panel. The unaffected composite panels showed that the panels returned to its original shape after removing the load. However, the experiments showed that 3D printing reduces the mechanical properties of recycled PET and PET. An overview is presented in this paper of the durability of the composite panel. The durability aspects for this research are UV radiation, elevated temperature and fire. The UV radiation showed that the glue from DELO ensures for a better adhesion , which allows reaching higher forces. Also, the showed to let recycled PET change into a yellowish color and becomes more brittle. At an elevated temperature of 80 ⁰C, recycled PET looses its stiffness and strength and can not take up forces when exposed. Recycled PET has melting temperature starting from 200 ⁰C and during a fire temperatures could reach up to 1000 ⁰C. This allows the core element to melt fully during a fire. The following chapters of this thesis will give an overview of the literature study and the experiments that were performed and how the composite panel can be integrated into a facade. Keywords: Thin glass, Recycled PET, PET, composite, 3D printing, UV radiation, elevated temperature, fire, Honeycomb pattern, Truss pattern.