C003 -- Building Envelope Thermal Activation to Reduce Summer Cooling Peak Demand: It Is All about Holistic Heat Transfer ✓ Most Recent

Summer peak electricity demand for cooling in U.S. is anticipated to have an increasing impact on the grid. At the same time, the increased renewable energy generation added to the grid will induce more variability. Grid-interactive efficient buildings are expected to support the electrical grid and provide flexibility as the penetration of renewable energy generation increases. Thermal energy storage can partially provide such support, and, among different technologies, phase change materials (PCMs) embedded in the building envelope can shift space conditioning energy demand away from peak hours. Thermal access to the energy storage on the envelope depends on the heat transfer between the indoor environment and the phase change material in the envelope, which is controlled by the thermal resistances that exist between them. Being able to control such thermal resistances using novel building activation approaches could augment the energy storage potential, determining access to the stored energy. This study numerically analyzes the ability of the combined effect of an optimized PCM in the drywall, thermal resistances, and variable interior heat transfer on their ability to effectively provide flexible response during a time-of-use of three hours in the afternoon using precooling and setback. The analysis particularly considers the peak summer cooling demand in a typical home in Phoenix, AZ. ResStock with EnergyPlus, its simulation engine, is modified to allow for variable heat transfer coefficients and thermal conductivities. Exterior walls, ceiling, and internal mass are individually analyzed with the focus on finding optimal sets of conditions for thermal storage. Preliminary results show that the thermal conductivity of the PCM, natural convection between the envelope and the living space is a "bottle neck" to suppress the PCM performance.. See more