How to use submetering to find energy waste in your business

A main utility meter shows overall consumption, but it cannot always explain what is driving it. Submeters provide more detailed data, helping businesses investigate patterns, identify unexpected usage and understand where efficiency improvements may be possible.

For organisations looking to reduce energy costs and carbon emissions, this additional visibility can turn energy data into practical action.

Key takeaways

• Energy submetering provides more detailed consumption data than a single main meter.
• Monitoring individual areas or equipment can help reveal unusual consumption and opportunities to reduce waste.
• Submetering is most useful when businesses regularly review the data and investigate unexpected patterns.

What is energy submetering?

Energy submetering involves installing additional meters below a site's main utility meter to measure consumption in greater detail.

Rather than seeing only the total amount of energy used across an entire site, a business can monitor selected areas separately.

Depending on the organisation, this might mean measuring individual buildings, departments, production areas or energy-intensive equipment.

The purpose is to understand where consumption occurs. Once a business can separate different sources of energy use, it becomes easier to investigate which activities are driving costs and where potential inefficiencies may exist.

How does submetering help identify energy waste?

Energy waste is difficult to address when businesses cannot see where consumption is occurring.

Submetering provides more granular information. By monitoring energy use over time, businesses can establish normal consumption patterns and investigate readings that do not fit those patterns.

For example, unexpectedly high consumption outside operating hours could indicate that equipment is being left running. A sudden increase associated with a particular process could warrant further investigation.

Submetering does not explain the cause automatically. It provides the evidence needed to identify where to look more closely.

Where should a business install submeters?

Installing submeters everywhere is not necessarily the most useful or cost-effective approach.

Businesses should first identify where additional information would improve decision-making. Priority areas could include significant energy users, separate operational areas or equipment where consumption cannot be distinguished through the main meter.

For a manufacturer, this could mean monitoring individual production processes or machinery. In a larger commercial building, separating different floors, departments or systems may provide more useful insight.

The right approach depends on the organisation's premises, operations and reasons for collecting the data.

Start with your existing energy data

Before introducing additional monitoring, understand what information is already available.

Green Economy advises businesses to measure and track energy consumption, explaining that understanding energy use is necessary before consumption and bills can effectively be reduced. Its guidance recommends using actual meter readings to calculate consumption over defined periods.

Existing bills, meter readings and monitoring systems can therefore provide a useful starting point.

Businesses can then identify where the existing information lacks sufficient detail and decide whether submetering would provide useful additional insight.

Establish a useful energy baseline

Submeter data becomes more valuable when there is something meaningful to compare it against.

Businesses should collect readings over a suitable period to understand normal energy use. Consumption will naturally vary with factors such as production levels, occupancy and operating hours.

Green Economy recommends accounting for changes in business activity when tracking energy performance and gives energy intensity as one way to compare energy use with turnover.

Understanding these variables reduces the risk of treating every increase in consumption as energy waste when it may instead reflect legitimate changes in activity.

Look for unusual patterns in consumption

Once sufficient data has been collected, businesses can start looking for patterns that warrant investigation.

These might include:

• energy use when a site should be inactive
• unexplained increases compared with normal consumption
• equipment consuming more energy than expected
• significant differences between comparable areas or processes
• consumption remaining high when production or occupancy falls

These patterns do not necessarily prove that energy is being wasted. Instead, they indicate where further investigation may be worthwhile.

Combining energy data with knowledge of day-to-day operations is essential when interpreting the results.

Investigate out-of-hours energy use

Out-of-hours consumption can be particularly useful to examine because fewer legitimate activities should be taking place.

If a submeter shows substantial energy consumption overnight, at weekends or during shutdown periods, investigate what remains operational.

Some equipment will need to run continuously, so businesses should not assume that all baseload consumption is unnecessary.

The objective is to understand which loads are essential and whether other equipment, lighting, heating or processes are operating when they do not need to be.

Clearer information can then support practical operational changes rather than relying on assumptions about where energy is being wasted.

Use submetering to check whether improvements are working

Energy monitoring can also help businesses understand what happens after an efficiency measure has been introduced.

By comparing consumption before and after a change, while considering factors such as production or occupancy, organisations can assess whether energy performance has improved.

This could be useful following an operational change or an investment in more efficient equipment.

Green Economy's sustainability consultancy uses monitoring data within resource and energy efficiency reviews and includes a review stage that assesses performance against actions taken.

Monitoring therefore supports an ongoing process of measuring, acting and reviewing rather than a one-off exercise.

What should you do when submetering identifies energy waste?

Finding unusual consumption is the beginning of the investigation, not the end.

Businesses should establish what is causing the pattern and determine whether action is appropriate. Some improvements may involve simple changes to operating practices, while others could require maintenance, equipment upgrades or investment in energy-efficient technology.

The potential action should be considered alongside its likely energy saving, cost, operational impact and available resources.

Green Economy's resource and energy efficiency reviews use monitoring data to assess energy use and develop tailored carbon reduction strategies, with actions prioritised according to cost, resource and investment.

When could green technology help reduce energy waste?

Monitoring may identify areas where existing equipment or systems are inefficient enough to justify investment.

Businesses should assess the business case carefully rather than assuming that replacing equipment is automatically the best solution.

Green Economy provides independent support for green technology decisions, including feasibility, planning, financing, procurement and supplier sourcing. It also provides independent quote comparison and review to help businesses assess potential investments and expected return.

This can help turn an opportunity identified through energy data into a more informed investment decision.

Make energy monitoring an ongoing process

The value of submetering comes from using the information it produces.

Businesses should review consumption regularly, investigate significant changes and assess whether completed actions are producing the intended results.

Energy use can change as equipment, operating hours, production and premises evolve. A pattern considered normal today may therefore become inefficient in the future.

Green Economy's approach to sustainability consultancy includes reviewing performance and reprioritising activities according to where the greatest impact can be achieved.

Regular monitoring helps provide the evidence needed to make those decisions.

How Green Economy can help

Green Economy's sustainability consultancy includes resource and energy efficiency reviews that use monitoring data and heat-imaging tools to assess energy use, building fabric and resource efficiency. Following an audit, its consultants can develop a tailored carbon reduction strategy and help prioritise actions according to cost, resources and investment.

Where monitoring identifies a case for investing in energy-efficient or renewable technology, Green Economy's supplier sourcing service provides independent, impartial support covering areas including feasibility, planning, financing, procurement and finding suitable suppliers. Its wider decarbonisation support can help businesses understand their carbon footprint and implement practical measures to reduce it.