The computer model described previously  has been used for Lunar bioregenerative life support system (BLSS) modeling. Critical factors include the supply scenario (closure, consumables, and spares), startup scenarios, energy cost, mission duration, and policy on allowable dumping of trash.A BLSS will support closure of all life support functions. However, startup may require some time before all support is available. Under some scenarios, closure of water is achieved at about one month, oxygen/carbon dioxide closure at two months, and food closure at three months after the first harvest of food staples. Mineral closure is less critical due to the lower masses involved, particularly of micronutrients, and may not be closed until large numbers of people are to be supported for long periods of time.Alternative startup scenarios include physico-chemical support during startup, remote startup, provision of commodities by supply during startup, and ramp-up of base manning. Remote startup is the most technically challenging, and would require a trade study between the increased automation and provision of physico-chemical regeneration equipment. Supply-based startup is the simplest option, but will be more massive than physico-chemical based startup. Ramp-up of base manning is an interesting case, but a subset of other options.An interesting startup scenario is the initial use of physico-chemical (PC) regeneration, with a transition to bioregenerative life support as the CELSS becomes capable of closing each loop. PC technology would be available from shorter, precursor, missions. Stored consumables would be used for contingency and minimal buffering. The physico-chemical system could be retained as additional contingency capability.A number of bioregenerative scenarios have been modeled, addressing cost-effectiveness over 10 years and system startup constraints.