Conceptual analysis and design of a partitioned multifunctional smart insulation

Building insulation performance in walls and roofs is typically assessed in terms of its R-value, a metric related to its ability to resist heat flow under steady state conditions. Past and present efforts by numerous researchers have resulted in a continued increase in achievable R-values. However, for most climates, there are times during a typical day and throughout a calendar year where it would be advantageous to enable switching between highly insulated and conductive states. A large energy savings potential exists for such an adaptive insulation by decreasing the load imposed on the heating or cooling system; however, practical realizations of adaptive insulation have not been fully developed. A new multifunctional insulation is presented in this paper where thin polymer membranes are positioned within a wall to create layers of air such that the role of natural convection becomes negligible. The heat passing through the wall must therefore travel through alternating layers of stagnant air and polymer membrane. To achieve the low R-value condition, the air is removed and the layers are compressed, essentially leaving only conduction through the polymer membranes. The focus of this paper is the analysis of such a multilayered wall in both the insulated and conductive states. Design strategies are presented for selecting suitable materials and wall geometry. The conceptual analysis presented here provides the framework for future studies focused on fabrication and experimental design of such a multifunctional smart insulation.