Abstract: Various embodiments of systems and methods for protecting various products and materials that are sensitive to variations in temperature, during the time that such sensitive products and materials are in transit or in storage. Phase Change Materials (“PCM”) are used to absorb heat, and thereby protect the sensitive products and materials. Various systems and methods for measuring current levels, and changes in, the residual latent energy in the PCM, and thereby determining the expected duration of temperature control for the sensitive products and materials. Various systems and methods for aggregating the measurements of changes in the residual latent energy of the PCM, and for communicating such measurements by wireless or wireline communication to an outside receiver of such information. Various systems and methods for taking action, based on measurements of changes in residual latent energy of the PCM, for protecting the temperature sensitive products or materials.