For a large part of its operating time, a lights-out factory is unmanned. This means that it can run without the need for lights and other services, such as heating and air-conditioning, which make it comfortable for human operators.
Labour is typically between 30% and 60% of a product's total manufacturing cost and, therefore, there is always a drive to reduce the labour requirement to a minimum.
The first approach to improving productivity per person was to load machines at the end of a day shift and let them run unattended until they completed their manufacturing processes. Next, machines were automatically fed with product so that they could operate continuously.
Despite the concept's potential benefits, there have been relatively few instances of the goal of the unmanned, lights-out factory being achieved. Perhaps this is because people remain the best way of solving manufacturing problems as they arise.