Energy waste isn’t always easy to identify across a manufacturing site. From production machinery and compressed air to heating, ventilation, cooling and lighting, multiple systems can consume electricity and gas throughout the working day, sometimes even when they’re not needed.

The challenge is that energy bills only tell part of the story. They show how much energy your business consumes and what it costs, but don’t necessarily reveal which machines, processes or operating practices are responsible for unnecessary consumption.

For manufacturers, this lack of visibility can make it difficult to control energy expenditure, particularly when inefficient equipment, poor maintenance or unnecessary running hours are adding to operating costs.

A manufacturing energy audit can help bridge that gap. By examining consumption patterns, equipment performance and how energy is used across your operations, an audit can identify potential inefficiencies and highlight where improvements could deliver value.

For some larger UK manufacturers, energy assessments may also form part of their obligations under the Energy Savings Opportunity Scheme (ESOS).

Understanding where your site uses energy, where it may be wasted and which improvements are worth prioritising is the first step towards reducing unnecessary costs and making better-informed energy decisions.

Key Takeaways

• Energy waste can occur across multiple manufacturing systems.
• Energy bills don’t reveal every source of inefficiency.
• Poor maintenance and unnecessary running increase energy consumption.
• Energy audits identify where potential savings may exist.
• Equipment performance and operating patterns influence energy efficiency.
• Some manufacturers have energy assessment obligations under ESOS.
• Audit findings can guide practical, prioritised efficiency improvements.

What Is an Energy Audit in Manufacturing and How Does It Work?

An energy audit in manufacturing is a structured assessment of how electricity, gas and other fuels are consumed across a site. It helps manufacturers understand where energy is being used, where inefficiencies may exist and which improvements could reduce unnecessary consumption.

Unlike reviewing energy bills alone, an audit looks more closely at the equipment, processes and operating practices that influence energy demand.

How Does a Manufacturing Energy Audit Work?

The process typically involves several stages:

• Energy data review: Examining around 12 months of utility bills and meter readings to understand consumption patterns.
• Site inspection: Reviewing machinery, operating schedules, maintenance practices and production processes.
• Energy measurement: Using existing meters, submeters or temporary monitoring equipment to assess consumption.
• Performance analysis: Comparing energy use against production output and operating requirements.
• Recommendations: Identifying potential improvements alongside estimated savings, costs and implementation priorities.

What Equipment Does an Energy Audit Assess?

The areas assessed depend on the manufacturing site, but commonly include production machinery, electric motors, pumps, compressed air systems, boilers, process heating, refrigeration, ventilation and lighting.

An audit may also investigate equipment running unnecessarily or consuming energy outside production hours.

Are Manufacturing Energy Audits Mandatory?

Some larger UK manufacturers must comply with the Energy Savings Opportunity Scheme (ESOS), which requires qualifying organisations to assess significant areas of energy consumption and identify saving opportunities.

However, a voluntary manufacturing energy audit doesn’t automatically meet ESOS requirements. Understanding the distinction helps businesses determine which assessment is appropriate for their operations.

Where Is Energy Most Commonly Wasted in Manufacturing?

Energy waste can occur across a manufacturing site, from machinery operating during production to equipment left running during quieter periods or outside working hours.

However, high energy consumption doesn’t necessarily mean a system is inefficient. Different manufacturing processes have different requirements, and some equipment naturally consumes more energy than others.

The challenge is understanding whether that energy is being used effectively. Poor maintenance, inefficient controls, unnecessary running hours and equipment performance can all contribute to avoidable consumption.

Looking at common sources of energy waste can help manufacturers identify which systems may benefit from closer investigation.

Energy-consuming system	Common source of energy waste	What an audit should check
Compressed air	Leaks and excessive pressure	Leak rates and compressor performance
Electric motors	Unnecessary running and poor load matching	Operating hours and load profiles
Industrial heating	Heat loss and inefficient combustion	Insulation and combustion performance
HVAC	Unnecessary heating, cooling or ventilation	Temperature settings and operating schedules
Production machinery	Idle running and standby consumption	Machine-level energy demand
Refrigeration	Inefficient controls and poor maintenance	Temperatures and operating cycles
Pumps and fans	Excessive flow or fixed-speed operation	Flow demand and control methods
Lighting	Unnecessary operation	Lighting schedules and occupancy

Identifying potential energy waste is only part of the process. Manufacturers also need to understand whether improvements could deliver meaningful savings without affecting production.

For example, compressed air leaks may increase consumption even when equipment is operating normally, while heat losses could create opportunities for better insulation or heat recovery.

Some issues may be addressed through maintenance or improved controls, while others require more detailed engineering assessments.

An energy audit helps establish which opportunities are worth investigating further, using measured consumption, implementation costs and operational requirements to guide decisions rather than relying on assumptions about where energy is being wasted.

How Can Manufacturing Energy Efficiency Be Improved After an Audit?

Manufacturing energy efficiency can be improved by acting on the opportunities identified during an energy audit. However, this doesn’t necessarily mean replacing equipment or making significant changes to production. The right approach depends on where energy is being wasted and which improvements could deliver value.

Reduce Compressed Air Waste

Compressed air systems can consume significant electricity, particularly when leaks or excessive pressure increase demand. Checking for leaks, optimising pressure settings and improving compressor controls can reduce unnecessary consumption while maintaining production requirements.

Improve Electric Motor Efficiency

Motors support conveyors, pumps, fans and other industrial equipment. Regular maintenance, reducing unnecessary running hours and reviewing motor sizing can improve efficiency. Variable-speed drives may also reduce consumption where equipment operates under changing loads.

Reduce Heating Losses

Industrial boilers, ovens and furnaces can lose useful heat during operation. Improving insulation or recovering waste heat through heat exchangers may reduce energy demand, depending on the process and available heat.

Monitor Energy Consumption

Submetering can help manufacturers understand how much energy individual machines or production lines consume. Comparing this information against production output makes it easier to identify inefficiencies and monitor improvements.

Assess Financial Value

Not every recommendation will justify investment. For example, a £12,000 improvement delivering £4,000 in annual savings has a three-year simple payback. Maintenance costs, equipment lifespan and operational requirements should also inform the decision.

Which Manufacturing Energy Audit Recommendations Should Be Prioritised?

An energy audit may identify several opportunities to reduce consumption, but that doesn’t mean every recommendation should be implemented immediately.

Some improvements, such as adjusting equipment schedules or repairing compressed air leaks, may be relatively straightforward. Others, including machinery upgrades or waste heat recovery, can require greater investment and technical assessment.

The right priority depends on the potential savings, implementation costs and how changes could affect production. A measure offering significant energy savings isn’t necessarily the most practical starting point.

Comparing recommendations against these factors can help manufacturers decide which improvements to address first and which require further investigation.

Energy efficiency measure	Main decision factor	Recommended action
Compressed air leak repair	Repair cost and leak severity	Detect, repair and retest
Equipment shutdown controls	Production and safety requirements	Review schedules and trial controls
LED lighting	Operating hours and replacement costs	Assess long-term savings
Variable-speed drives	Motor load profile and suitability	Complete technical assessment
Thermal insulation	Heat loss and installation feasibility	Calculate potential savings
Energy submetering	Existing data gaps	Prioritise critical equipment
Waste heat recovery	Heat availability and usable demand	Conduct feasibility study
Equipment replacement	Capital cost and equipment condition	Complete investment appraisal

Prioritising improvements shouldn’t simply mean choosing the cheapest option or the measure with the greatest estimated savings.

Lower-cost changes may offer a practical starting point, provided they don’t affect production or product quality. Larger projects may require detailed financial and engineering assessments before investment decisions are made.

Manufacturers should also consider expected savings in kWh and pounds, implementation timescales and who will be responsible for delivering each improvement.

Once changes are introduced, monitoring consumption against an appropriate baseline can help establish whether savings are being achieved, accounting for changes in production, operating hours and other relevant conditions.

Turn Manufacturing Energy Waste Into Measurable Savings

Energy waste isn’t always obvious across a manufacturing site. Inefficient equipment, poor controls, heat losses and unnecessary running hours can all contribute to higher operating costs without providing additional value.

A manufacturing energy audit can help identify where these inefficiencies exist and which improvements could make the greatest difference. Rather than simply highlighting problems, the findings can support a practical action plan based on potential savings, investment requirements and operational priorities.

However, improving efficiency shouldn’t be treated as a one-off exercise. Ongoing energy monitoring and submetering can help manufacturers understand whether changes are delivering results and identify new opportunities as production requirements evolve.

At The National Energy Hub, we look at the wider energy picture, considering your consumption, operating requirements and longer-term business objectives. Get in touch to discuss your manufacturing site’s energy requirements and explore where improvements could deliver value.

Frequently Asked Questions About Manufacturing Energy Audits

What is a manufacturing energy audit?

A manufacturing energy audit is a structured review of how energy is consumed across a factory’s equipment, processes and supporting systems. It helps identify where energy may be wasted or used inefficiently, using consumption data and site observations to recommend improvements that could reduce operating costs.

How much does a manufacturing energy audit cost in the UK?

There’s no fixed cost for a manufacturing energy audit in the UK. The price depends on the size of your facility, the complexity of production processes and the level of assessment required. Additional monitoring, specialist inspections or detailed reporting may also influence costs, so quotations should reflect your site’s requirements.

How long does a factory energy audit take?

The time required depends on the size of the manufacturing site, its equipment and operating patterns. Smaller facilities may require less time on-site, while complex operations or multiple production shifts can extend the assessment. Data analysis, additional monitoring and preparing recommendations may also take time beyond the initial inspection.

Are manufacturing energy audits mandatory in the UK?

Not every UK manufacturer is required to undertake an energy audit. However, qualifying large organisations must comply with the Energy Savings Opportunity Scheme (ESOS), which involves assessing energy consumption and identifying potential savings. Eligibility depends on organisational criteria, so manufacturers should check current government guidance to understand their obligations.

Which manufacturing equipment consumes the most energy?

Energy consumption varies considerably between manufacturing sites. Industrial heating, compressed air systems, electric motors, refrigeration and production machinery can all account for significant demand, depending on the processes involved. An energy audit helps establish which equipment consumes the most energy at your site rather than relying on general industry assumptions.

Can an energy audit reduce manufacturing electricity bills?

An energy audit doesn’t directly reduce electricity consumption, but it can identify opportunities to lower unnecessary usage. These might include repairing compressed air leaks, improving equipment controls or reducing idle running hours. Actual savings depend on which recommendations are implemented, equipment performance, operating requirements and your electricity tariffs.

How often should a manufacturing facility conduct an energy audit?

There’s no single audit frequency that suits every manufacturer. The right approach depends on operational changes, energy consumption and regulatory requirements. Organisations covered by ESOS follow a four-year compliance cycle, while equipment upgrades, increased production or unexpected energy usage may justify additional assessments between formal audits.

What is the difference between energy auditing and energy monitoring?

An energy audit provides a structured assessment of how energy is used and where improvements could be made. Energy monitoring involves tracking consumption over time to understand performance and identify unusual patterns. Used together, they help manufacturers identify inefficiencies and assess whether implemented changes are delivering the expected results.

What documents are required for a manufacturing energy audit?

Manufacturers should typically prepare electricity and gas bills, available meter readings, equipment inventories and operating schedules. Production data, maintenance records and previous energy assessments can also provide useful context. The exact information required depends on the audit scope and the systems being assessed across your manufacturing site.

How are manufacturing energy savings measured after an audit?

Energy savings are typically measured by comparing consumption before and after improvements are implemented. Establishing a reliable baseline helps manufacturers understand whether changes are delivering results. Comparisons should also account for production volumes, operating hours and other relevant conditions, using meter data and energy performance indicators where available.