Frozen storage of food comprises a large portion of global energy consumption, and in light of growing demand and increasing global temperatures, new solutions for increasing its energy efficiency are needed. Past efforts to improve refrigeration efficiency have focused primarily on improving the vapor-compression cycle and developing alternative heat pumps, but this study looks beyond the technology of cooling to the fundamental thermodynamics at play in the freezing of biological matter. Conventionally, food is frozen under isobaric conditions, e.g. at constant (atmospheric) pressure. Herein we use fundamental thermodynamic analyses to demonstrate that the process of freezing in an isochoric (constant volume) system requires up to 70% less energy compared to conventional freezing, and we develop novel phase change models to demonstrate newly discovered thermal effects that provide isochoric systems with exceptional temperature stability when exposed to ambient fluctuations (such as those encountered within freezers or during transportation), with the potential to substantially improve the energy efficiency of long-term storage and enhance preserved food quality. Our results show that a simple change in the thermodynamic state in which food is frozen and stored, from isobaric to isochoric, has the potential to substantially reduce the energy consumption of the global food storage industry, without the need to make major changes to existing refrigeration infrastructure.