Development and Performance Evaluation of Active Insulation Systems using Solid-State Thermal Switches

Traditional building envelopes have passive insulation systems that cannot respond to dynamic changes in the environment. An Active Insulation System (AIS) consists of Active Insulation Materials (AIMs) that dynamically vary the thermal conductivity of the insulation system. Several researchers have evaluated the impact of AIS on building thermal and energy performance by using simulation tools. Up to 70% savings in annual heating and cooling energy and significant reductions in peak demand have been predicted for some climates with wall systems employing AIS. However, materials and assembly development have not yet achieved a cost-effective product that achieves the required performance. In this study, we present the process to develop an AIS that we will install in a test hut for its performance evaluation. Minimum performance criteria of the AIS system are developed based on Rmin/Rmax ratio, required time and efficiency to switch states, and cost estimates. The next steps carried out during this study are creating the concept to meet the requirements, predicting the performance via simulations, developing the experimental setup for bench-scale testing, and finally, constructing a full-scale wall assembly and monitoring the performance when exposed to natural weather conditions. The selected approach uses off-the-shelf products to create an AIS that can switch R-value between ~1 ft²·°F·h/BTU (0.18 m²·K/W) and ~7 ft²·°F·h/BTU (1.23 m²·K/W) and have a switching time of less than one minute between R-high and R-low.