Steam sterilization in hospitals is an energy and water intensive process. Our aim was to identify opportunities to improve electricity and water use. The objectives were to find: the time sterilizers spent active, idle and off; the variability in sterilizer use with the time of day and day of the week; and opportunities to switch off sterilizers instead of idling when no loads were waiting, and the resultant electricity and water savings.

Analyses of routine data for one year of the activity of the four steam sterilizers in one hospital in Melbourne, Australia. We examined active sterilizer cycles, routine sterilizer switch-offs, and when sterilizers were active, idle and off. Several switch-off strategies were examined to identify electricity and water savings: switch off idle sterilizers when no loads are waiting and switch off one sterilizer after 10:00 h and a second sterilizer after midnight on all days.

Sterilizers were active for 13,430 (38%) sterilizer–hours, off for 4822 (14%) sterilizer–hours, and idle for 16,788 (48%) sterilizer–hours. All four sterilizers were simultaneously active 9% of the time, and two or more sterilizers were idle for 69% of the time. A sterilizer was idle for two hours or less 13% of the time and idle for more than 2 h 87% of the time. A strategy to switch off idle sterilizers would reduce electricity use by 66 MWh and water use by 1004 kl per year, saving 26% electricity use and 13% of water use, resulting in financial savings of AUD$13,867 (UK£6,517) and a reduction in 79 tonnes of CO₂ emissions per year. An alternative switch-off strategy of one sterilizer from 10:00 h onwards and a second from midnight would have saved 30 MWh and 456 kl of water.

The methodology used of how hospital sterilizer use could be improved could be applied to all hospitals and more broadly to other equipment used in hospitals.