This paper aims to present an economic model characterized by a set of axioms that are consistent with the laws of thermodynamics. Two new axioms-weak G-disposability (i.e., weak directional disposability) and output essentiality-are introduced to satisfy the materials balance principle and the entropy law, respectively. The axiomatic production model is compared to other well-known production models that account for the joint production of good and bad outputs to illustrate the advantages of the new modeling approach.