What defines a thermal layer?

Currently we use lots of composite materials in structures, such as ACM cladding, which combines foam insulation covered in a thin aluminium layer. This research will look into what types of materials are commonly in use in the built environment.
It will then look at what determines whether a layer of material contributes to the thermal properties of the entire system. Whether this be, thermal properties, layer thickness, or interface connection. The interaction between these properties, and the thermal resistance will be analysed to better understand how composite materials work in terms of fire safety, and therefore allow safer construction materials to be used. This project would be highly experimental based, and my existing knowledge of the fire lab apparatus would allow for me to begin gaining results immediately. Initially I would perform experiments using the wide variety of apparatus currently in the fire lab, before eventually creating my own bespoke apparatus to properly investigate the problem.
The aim of this project is to provide a testing method to understand the interaction between layers in a composite material so as to understand the thermal behaviour. This will then allow for better understanding of these materials so that they can be used safely.