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Programmable logic controllers (PLCs) can improve industrial efficiency by automating repeatable tasks, coordinating connected equipment, and making operating data easier to collect and use. They are an enabling part of an efficiency project—not an efficiency upgrade by themselves. Savings depend on the control strategy, sensors, equipment, process design, and how people respond to the information.
Where PLCs can improve efficiency
A PLC reads input signals from equipment and sensors, runs programmed logic, and controls outputs such as motors, valves, pumps, and alarms. In a plant, its efficiency gains usually come from controlling when and how equipment operates, coordinating sequences, or connecting operations to useful data.
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Coordinate equipment and utilities
A PLC can coordinate pumps, chillers, and other process equipment with variable speed drives so they respond to actual demand rather than running at an unsuitable fixed setting. At Codd Mushrooms, a PLC-based chilled-water control solution used variable speed drives. Mitsubishi Electric reports more than 5,400 kWh saved in the first week and potential savings of up to €40,000 per year; the annual amount is potential, not a guaranteed or independently established outcome. Mitsubishi Electric’s case description does not establish that a PLC alone produced the savings.
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Networked PLCs can provide a common control point for equipment that otherwise operates in separate systems. In an industrial-facility case published in 2018, phased upgrades included centralized control of production machines, along with work on HVAC, IT infrastructure, lighting, occupancy controls, and utilities. The facility expanded and production grew during the work. The case reports over 450,000 kWh in further annual energy reduction after three years of upgrades and monitoring, but it does not isolate the PLC contribution. The published case study also reports 146,600 kWh of ongoing annual savings after its first phase, which included compressed air, exterior lighting, water heating, and controls for incoming water and gas services.
#1 Best Overall
Reduce manual data handling
Automation can improve operational efficiency even when energy savings are not measured. A semi-trailer manufacturer operating three plants replaced a PC-based system with PLCs and barcode-based data capture, reducing manual tasks and paperwork. Mitsubishi Electric’s 2021 release quotes the project’s systems integrator, ACS: “The new control systems have been problem-free and doing exactly what they wanted it to do.” This is an integrator’s assessment, not a quantified independent performance measurement. Read the project description.
Make energy and production data actionable
Energy measurements become more useful when they can be interpreted alongside production. Siemens’ Brau Union Österreich customer story describes an energy management system that collected energy and production data, supported batch-level energy reviews, and standardized reporting across sites. Siemens attributes a 0.6% reduction in energy consumption per year to the system; this is a vendor-reported customer outcome, not a general PLC benchmark. The project defined around 1,000 measuring points across five sites. Those figures describe that project’s scope, not a typical installation. Siemens’ case story quotes Brau Union’s Eng. Johann Hölzl: “We need a cross-plant energy management system which allows easy data recording and standardized reporting.”
Modernize controls and support maintenance
A modernization project can improve maintainability, reliability, and integration without necessarily changing the process itself. Schneider Electric’s 2025 forest-industry case describes modernization of 45 PLC systems, integration with an existing distributed control system (DCS), redundancy, and the ability to make online changes. The case reports a 1.5-year return on investment for that customer. It is one project’s reported result, not a typical payback period. Schneider Electric’s case provides the project context.
What the case-study numbers do—and do not—show
The examples show that measurable gains have been reported at real facilities, but most combine PLCs with other equipment, software, or process changes. Their results are not directly comparable: sites, boundaries, time periods, and project scopes differ. Treat them as evidence of possible outcomes, not as a forecast for your plant.
Rank #3
- The industrial-facility study reports annual energy savings across phased facility upgrades, including lighting, utilities, HVAC, and centralized production control; the savings cannot be attributed to PLCs alone.
- The Codd Mushrooms account describes a PLC-based control solution with variable speed drives; its first-week figure and potential annual savings refer to that specific chilled-water application.
- The Brau Union figure is Siemens’ reported annual reduction in energy consumption associated with an energy management system; it is not a universal expected reduction from installing PLCs.
- The forest-industry modernization’s ROI reflects one customer’s costs and benefits, not a general payback promise.
How to evaluate a PLC efficiency project
1. Identify the operating problem
Start with the bottleneck or waste you want to address: unnecessary run time, poor sequencing, avoidable downtime, excessive manual recording, inconsistent product quality, or limited visibility into energy use. Choose a control scope that matches the problem, from a single machine or utility system to production-line coordination or plant-wide monitoring.
2. Establish a baseline before changing controls
Record performance for a representative period before implementation. Pair energy and resource use with production output so changes in workload do not masquerade as efficiency gains. Track the measures that match the project:
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- Energy per unit of output, plus total energy use
- Downtime and its causes
- Throughput, scrap, and rework
- Maintenance effort and equipment faults
- Manual work or data-entry time, where labor handling is part of the goal
3. Check equipment and integration fit
Confirm that the PLC can work with the existing instrumentation, motors and drives, human-machine interface (HMI), networks, and any DCS or manufacturing execution system (MES) interfaces involved. Decide whether additional meters or sensors are needed and whether data can be recorded at intervals useful for the process. An energy dashboard cannot compensate for missing or unreliable measurements.
4. Include reliability and lifecycle needs
Before selecting a modernization or expansion approach, assess network readiness, available support and spare parts, redundancy needs, documentation, and staff familiarity with the controls. Online change capability may help reduce disruption during modifications, but it should be considered within the site’s safety and change-management practices. Include commissioning, training, and ongoing maintenance in the project cost.
Best Value
5. Measure the result against the baseline
After commissioning, compare the same measures over a comparable operating period and normalize energy by output. Document the system boundary, production conditions, and simultaneous upgrades so the result can be interpreted honestly. Calculate site-specific return using implementation and commissioning costs against measured energy, labor, downtime, and quality effects; do not transfer another facility’s savings or ROI directly to your own.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.When a PLC upgrade is a strong candidate
A PLC project is most compelling when a defined operational problem can be addressed through better control or coordination and the plant can measure whether the change worked. It may be harder to justify from energy savings alone when the process lacks a baseline, production is highly variable, key measurements are unavailable, or the proposed project combines many upgrades that cannot be evaluated separately.
For an upgrade decision, compare the application scope, equipment and controls fit, measurement readiness, reliability and maintenance requirements, and full lifecycle economics. That gives operations and engineering teams a more useful basis for investment than an unqualified percentage-saving claim.
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