Data underpinning "Green scheduling of a two-machine flowshop: Trade-off between makespan and energy consumption"

Sustainability considerations in manufacturing scheduling, which is traditionally influenced by service ori-
ented performance metrics, have rarely been adopted in the literature. This paper aims to address this gap
by incorporating energy consumption as an explicit criterion in shop floor scheduling. Leveraging the vari-
able speed of machining operations leading to different energy consumption levels, we explore the potential
for energy saving in manufacturing. We analyze the trade-off between minimizing makespan, a measure of
service level and total energy consumption, an indicator for environmental sustainability of a two-machine
sequence dependent permutation flowshop. We develop a mixed integer linear multi-objective optimization
model to find the Pareto frontier comprised of makespan and total energy consumption. To cope with com-
binatorial complexity, we also develop a constructive heuristic for fast trade-off analysis between makespan
and energy consumption. We define lower bounds for the two objectives under some non-restrictive condi-
tions and compare the performance of the constructive heuristic with CPLEX through design of experiments.
The lower bounds that we develop are valid under realistic assumptions since they are conditional on speed
factors. The Pareto frontier includes solutions ranging from expedited, energy intensive schedules to pro-
longed, energy efficient schedules. It can serve as a visual aid for production and sales planners to consider
energy consumption explicitly in making quick decisions while negotiating with customers on due dates.
We provide managerial insights by analyzing the areas along the Pareto frontier where energy saving can be
justified at the expense of reduced service level and vice versa.