The U.S. Department of Energy Building Technologies Program's goal of developing high-performance, energy-efficient buildings will require more cost-effective, durable, energy-efficient building envelopes. Forty-eight percent of the residential enduse energy consumption is spent on space heating and air conditioning. Reducing envelope-generated heating and cooling loads through application of phase-change material (PCM) enhanced envelope components can facilitate maximizing the energy efficiency of buildings. Field testing of prototype envelope components is an important step in estimating their energy benefits.

An innovative PCM (nano-PCM) was developed with PCM encapsulated with expanded graphite (interconnected) nanosheets, which is highly conducive for enhanced thermal storage and energy distribution, and is shape-stable for convenient incorporation into lightweight building components. During 2012, two test walls with cellulose cavity insulation and prototype PCM-enhanced interior wallboards were installed in a natural exposure test (NET) facility in Charleston, SC. The first test wall was divided into four sections separated by wood studs and thin layers of foam insulation. Two sections contained nano-PCMenhanced wallboards: one was a three-layer structure in which nano-PCM was sandwiched between two gypsum boards, and the other one had PCM dispersed homogeneously throughout graphite nanosheet-enhanced gypsum board. The second test wall also contained two sections with interior PCM wallboards; one contained nano-PCM dispersed homogeneously in gypsum and the other was gypsum board containing a commercial microencapsulated PCM (MEPCM) for comparison. Each test wall contained a section covered with gypsum board on the interior side that served as control or a baseline for evaluation of the PCM wallboards. The walls were instrumented with arrays of thermocouples and heat flux transducers. This paper presents the measured performance and analysis to evaluate the energy-saving potential of the nano-PCM-enhanced building components.

Presented at Thermal Performance of Exterior Envelopes of Whole Buildings XII, December 2013