The external walls of buildings can also be thermally insulated with transparent insulating materials or semi-transparent. For example with glass, Plexiglas, polycarbonate or acrylic glass panels. Panels of this type are able to transform a wall into a kind of heat accumulator, with all the advantages of the case. Let's see how.
The panels of transparent insulating materials during the day they let the sunlight through, allowing the energy to heat the surface of the wall. Instead at night or in bad weather, they slow down the dispersion of heat to the outside, keeping it inside for longer. Compared to a classic insulating thermal coat, these materials offer the advantage of maximizing solar gains.
As with the other thermal insulators used for the thermal insulation of buildings (cork, wood fiber, mineral wool, polystyrene, etc.) also in transparent insulating materials the thermal conductivity depends on the geometric structure of the molecules (alveoli, prisms or other) which transmits the heat assumed by the external wall with a certain delay inside (the so-called phase shift time).
However what you usually want to achieve by treating the facades with transparent insulating materials it is the temporary accumulation of heat and its emission in the evening or during the night. However, even the solar contribution must not be excessive and if on the one hand i transparent insulating materials they must always be protected externally by a glass plate, in some cases it is also necessary to provide sunshades.
Also vacuum insulation materials they are generally marketed in vacuum-insulation panels - VIPs composed of a core of nanoporous material, usually pyrogenic silica or airgel from which the air has been evacuated, closed in a pressure-resistant multilayer sheet. The quality of the vacuum is fundamental in performance and it is the pressure that determines it.
In the case of vacuum insulation materials, the goal is not to maximize solar gains by allowing light to pass through the panel on the facade, but rather to minimize thermal conductivity. Which actually happens since i vacuum insulating panels they have a very low conductivity and contain the insulating capacity of 40 cm of polystyrene in 5 cm thickness.