The current position on the environmental advantages offered by returnable versus one-way glass packages is discussed. The energy needs of both options are considered as important parameters. A critical concept in the published LCA studies is the breakage rate, which serves to estimate the number (n) of returns that a functional unit of bottles can perform. Normally the energy of production of the glass (E) is divided by n. The authors consider this concept too theoretical and for long-term situations demonstrate that, in all LCA calculations, an energy value equal to 2E/n should be used. This value is useful in calculating the break-even point. The paper summarizes the effect of different breakage rates and distribution distances on the break-even point. It is clear that, for breakage rates below 5%, returnable glass bottles remain competitive and advantageous, even for quite long distribution distances. The methology proposed should be applicable to other materials. Copyright © 1999 John Wiley & Sons, Ltd.