Nearly 50% of all energy produced in the US is wasted as heat in the form of ‘noisy’ terahertz (THz) phonons. Unprecedented control of waste heat is enabled by the design of media that make thermal phonons more coherent. This may lead to the energy available from current generation technologies being doubled by reduced loss to heat. By selectively tailoring the nature and magnitude of interactions between phonons through the supporting medium to control the level of coherence of sound waves, NewFoS research will develop strategies to overcome energy loss.