Agglomerate tile structures and ceiling tile structures: The agglomerate tile structures can be of a single layer having an intermixed granular base medium comprised of one or more subcomponent materials (e.g., powdered, crushed, chips, and/or other broken pieces of varying sized particles, of quartz, granite, limestone, marble, glass, ceramic, semiprecious stones, etc.), plus a binder material and a PCM component; or the agglomerate tile structures can be of multiple layers, such as having an outer wear-layer substantially absent of PCM component--this outer wear-layer being bonded or otherwise incorporated with a second layer comprised of a binder material and a PCM component, substantially absent of the granular base medium. While applicants contemplate that the tile structures can be of a myriad of shapes and sizes, and associated features of the apparatus will be accordingly sized and fabricated of material(s) suitably compatible, traditionally-shaped generally planar tiles as well as tiles having curvilinear surfaces, may be fabricated according to the invention.
 The invention disclosed herein was made with United States government support awarded by the Department of Energy, award N.sup.o. DE-FC26-00NT40999. Accordingly, the U.S. Government has certain rights in this invention.