1. Electric motors and drives

Electric motors are the single largest consumer of electricity in most manufacturing facilities. Across British industry, motors account for an estimated 65–70% of total industrial electricity consumption, powering everything from conveyor systems and fans to pumps, compressors and machine tools.

The inefficiency in most motor-driven systems doesn’t come from the motors themselves — modern motors are highly efficient at full load — but from the way they’re operated. Motors running at fixed speed to meet variable demand are inherently wasteful. A fan or pump running at full speed to move a variable volume of air or fluid dissipates the excess energy as heat or mechanical resistance.

What to do: Installing variable speed drives (VSDs) on motors that operate under variable load conditions is one of the highest-return energy investments available to manufacturers. The energy consumed by a fan or pump is proportional to the cube of its speed — reducing speed by 20% cuts energy consumption by nearly 50%. Payback periods of one to three years are common, and the savings persist for the lifetime of the equipment.

2. Compressed air systems

Compressed air is often called the fourth utility — alongside gas, electricity and water — and in many manufacturing facilities it’s the most expensive one per unit of energy delivered. The overall efficiency of a typical compressed air system, from electrical input to useful work output, is often below 10%. The rest is lost as heat, leakage and pressure drop.

Leaks alone typically account for 20–30% of compressed air production in facilities without an active leak detection programme. In a large facility, that can represent tens of thousands of pounds of wasted energy annually.

What to do: Commission a compressed air audit. Leak detection surveys using ultrasonic equipment can identify and quantify leakage across the system quickly and cost-effectively. Beyond leak repair, consider whether system pressure can be reduced — every 1 bar reduction in system pressure saves approximately 7% of compressor energy — and whether heat recovery from compressors can be used to offset heating costs elsewhere on site.

3. Process heating

For manufacturers involved in metalworking, food processing, ceramics, glass, chemicals or plastics, process heating is typically the dominant energy cost. Whether delivered by gas-fired furnaces, ovens, kilns, steam boilers or electric resistance heaters, process heating often accounts for 50–80% of total energy consumption in heat-intensive industries.

Inefficiency in process heating arises from multiple sources: poor insulation leading to heat loss through surfaces, excess air in combustion processes, inefficient heat transfer, and the energy embodied in waste heat discharged to atmosphere.

What to do: The hierarchy of interventions for process heating runs from insulation and combustion optimisation at the bottom through to process redesign and waste heat recovery at the top. Heat recovery — capturing waste heat from furnaces, ovens or flue gases and using it to preheat incoming material or air — can reduce fuel consumption by 20–40% in many applications. For steam users, a steam system audit typically identifies savings of 10–20% in most facilities.

4. HVAC and space heating

Heating, ventilation and air conditioning systems in manufacturing facilities are often significant energy consumers, particularly in large, high-bay buildings with high air change requirements, or in facilities with controlled environment requirements for temperature-sensitive processes or products.

Many industrial HVAC systems were designed and installed decades ago, and are significantly less efficient than current-generation equipment. Oversized systems, poorly calibrated controls, inefficient heat distribution and inadequate insulation all contribute to higher-than-necessary consumption.

What to do: Start with controls. Heating and ventilation systems that run to fixed schedules regardless of occupancy, outside temperature or production activity are common in manufacturing facilities and represent straightforward savings. Building energy management systems (BEMS) that adjust HVAC operation dynamically based on actual conditions can reduce heating and ventilation energy by 20–30% without any capital investment in the plant itself. For facilities with older boiler plant, modern condensing boilers or heat pumps can deliver significant efficiency improvements.

5. Lighting

Industrial lighting accounts for a smaller share of total energy consumption than motors or process heating, but it remains a meaningful cost — particularly in facilities operating across multiple shifts or with large footprints that require continuous illumination.

High-bay metal halide or fluorescent luminaires, which remain common in older manufacturing facilities, are significantly less efficient than modern LED alternatives. They also have substantially longer warm-up times, making them unsuitable for occupancy-controlled switching without modification.

What to do: LED replacement programmes in industrial facilities consistently deliver energy savings of 50–70% on lighting loads, with payback periods typically below three years at current electricity prices. Combining LED replacement with daylight-linked dimming controls and occupancy sensing in areas with intermittent use extends the savings further. For facilities operating multiple shifts, the savings from LED replacement are proportionally higher.

6. Refrigeration and cooling

For food manufacturing, pharmaceutical production, cold storage and distribution operations, refrigeration is typically the largest single energy load — often exceeding 50% of total site electricity consumption. Even in facilities where refrigeration is not a core process requirement, cooling systems for machinery, products or controlled environments can represent a significant overhead.

Refrigeration systems lose efficiency through condenser fouling, refrigerant degradation, poor insulation on cold rooms and pipework, and systems operating at lower temperatures than required.

What to do: Regular maintenance — condenser cleaning, refrigerant top-up and leak checking, door seal replacement on cold rooms — maintains system efficiency and is often overlooked. Beyond maintenance, consider whether setpoint temperatures can be raised in any areas without compromising product quality or safety, and whether free cooling — using outside air to supplement mechanical cooling during cooler periods — can reduce compressor run hours.