Potential analysis of a new removable insulation system

Abstract In this paper, the potential of a facade element with switchable U -value and g -value is investigated. This new switchable facade element consists of a series of air-filled cavities separated by opaque films, that can be rolled up or down between two fixed layers, thus switching the thermal and optical properties from a thermally insulating state to a conducting state. A first prototype has been built and measured in the insulating state and the properties of the facade element have been optimized using a theoretical analysis at the facade level. The U -value can be switched from a value of 0.35 W m −2  K −1 in the insulating state to a value of 2.7 W m −2  K −1 in the conducting state. Building energy simulations using EnergyPlus showed that the sum of the heating and cooling demands could be reduced by about 30% with the switchable insulation used as a window application or in front of an opaque massive wall. Even better performance could be achieved by reducing the frame or edge losses. The influence of the thermal mass, and finally the influence of orientation on the overall performance are also investigated and were found to be non-negligible.