Energy-saving policies for temperature-controlled production systems with state-dependent setup times and costs

•We trade off energy and waiting costs in M/G/1 queues with state-dependent setups.•We prove the optimal policy structure for a fluid queue approximation.•Various effective policies are developed for the M/G/1 queue.•The best performing policy depends on both the queue length and the temperature.•Policies based on only the queue length are typically very effective.