How Can Businesses Identify Out-of-Hours Energy Waste?

Energy waste doesn't stop when the working day ends. Heating, ventilation, lighting, refrigeration and other equipment can continue consuming energy long after a building has emptied. Across a multi-site estate, that unnecessary consumption can add up to a significant operating cost.

The challenge is knowing what is still running, whether it needs to be, and how much it is costing the business.

In this guide, we explain how to identify out-of-hours energy waste using half-hourly energy data, building controls and practical site checks. We'll also cover the common causes of unnecessary consumption and how businesses can prevent it from returning.

What is out-of-hours energy waste?

Out-of-hours energy waste is energy consumed when a building or piece of equipment is not being used as intended, and there is no operational reason for it to remain running.

Common examples include:

• Heating or air conditioning operating before staff arrive or after they leave.

• Lights remaining on in empty offices, shops, restaurants or storage areas.

• Ventilation systems running at full capacity when buildings are unoccupied.

• Equipment continuing to operate over weekends and bank holidays.

• Heating and cooling systems running simultaneously.

• Controls following outdated schedules that no longer reflect opening hours.

Not all out-of-hours consumption is waste. Refrigeration, security systems, emergency lighting, IT equipment and certain ventilation systems may need to operate continuously. The objective is to distinguish essential energy use from consumption that could be reduced without affecting safety, comfort or business operations.

For businesses managing dozens or hundreds of sites, this can be difficult to establish through occasional site visits alone. Energy data provides a starting point. Our commercial energy audit guide explains how businesses can use energy data to identify potential savings opportunities.

How can businesses identify energy waste overnight?

The most effective starting point is to examine when energy is being used, rather than looking only at how much is consumed over a month.

Monthly bills show total consumption over a period, but they rarely reveal whether a building used unnecessary energy at 2 am on a Tuesday or throughout an unoccupied weekend.

There are four practical ways to investigate out-of-hours energy use.

1. Analyse half-hourly energy data

Half-hourly electricity data records consumption across 48 periods each day. This makes it possible to see how energy use changes throughout the day and night.

Businesses can often obtain this data through their energy supplier or existing metering arrangements.

When reviewing the data, look for:

• A high overnight baseload: Energy consumption remains elevated even when the building is empty.

• Early morning increases: Equipment starts consuming energy well before the site opens.

• Late evening consumption: Energy use remains high after closing time.

• Weekend patterns: Consumption remains similar to a normal trading day despite reduced occupancy.

• Unexpected spikes: Energy use rises at unusual times without an obvious operational explanation.

Comparing several weeks of data is more useful than looking at a single night. It helps distinguish recurring patterns from one-off events, unusual trading hours or legitimate operational requirements.

For a multi-site business, the same analysis can be repeated across the estate to identify which locations warrant further investigation.

Clearworld offers a free data audit to help identify unusual consumption patterns, potential out-of-hours usage and energy-saving opportunities. You can find out more about the audit or get in touch with Clearworld.

2. Compare energy use with opening hours

Energy consumption only becomes meaningful when you know how a building is supposed to operate.

Start by documenting each site's normal opening hours, staff shifts, cleaning schedules, delivery periods and any overnight operations. Then compare those times with the energy profile.

For example, a restaurant may close to customers at 10 pm but continue using significant electricity until midnight. That might be explained by cleaning, food preparation or refrigeration. If the elevated consumption continues until 4 am, however, it is worth investigating further.

The same principle applies to retail stores, offices, warehouses and leisure facilities. A building's trading hours are not necessarily the same as its occupied hours, and neither automatically tells you when every piece of equipment should be running.

For larger estates, this comparison should be carried out site by site. A single schedule applied across every location may not reflect different opening hours, layouts or operational requirements.

3. Check building management system (BMS) schedules

A building management system can help control heating, ventilation, air conditioning and other connected equipment. However, its schedules and settings need to reflect how the building is actually used.

Over time, opening hours change, equipment is replaced, and temporary overrides can become permanent. A system may continue following its original commissioning schedule even when the business has changed how it operates.

Check whether:

• Heating and cooling start and stop at the correct times.

• Weekend and bank holiday schedules are accurate.

• Temperature setpoints are appropriate for occupied and unoccupied periods.

• Manual overrides are still necessary.

• Equipment outside the BMS is operating as intended.

A BMS schedule tells you what the system is instructed to do. It does not, by itself, prove that every connected asset is behaving as expected.

Where possible, compare scheduled operation with actual energy consumption and equipment status. If the BMS indicates that a system should be off but energy use remains unusually high, further investigation may be needed.

If your existing system isn't giving you the visibility or control you need, read our guide to BMS optimisation to understand how you can improve performance without necessarily replacing the system.

4. Investigate the equipment responsible

Whole-building meter data can show when energy is being consumed, but it may not identify the equipment responsible.

If an overnight pattern looks unusual, investigate the systems most likely to be contributing to it. Depending on the building, these may include HVAC plant, refrigeration, hot water systems, lighting, extraction fans or other high-energy equipment.

Check equipment schedules, operating status, controls and maintenance records. Where the cause remains unclear, additional monitoring at equipment or circuit level can help isolate the source.

The aim is to move from identifying a suspicious energy pattern to understanding what is causing it, what action is appropriate, and how the result will be measured.

Clearworld's Vision iQ energy management system brings energy and equipment information together to help businesses monitor performance, identify unusual consumption and manage connected equipment.

What equipment wastes the most energy when left running?

The answer depends on the building, its equipment and its operating requirements. However, several systems are worth investigating first.

Heating, ventilation and air conditioning (HVAC)

Heating and cooling systems can consume substantial amounts of energy, particularly when they operate outside occupied hours or maintain unnecessary temperatures. Incorrect schedules, poorly configured controls and simultaneous heating and cooling are all potential causes.

Refrigeration

Refrigeration often needs to run continuously, particularly in food retail and hospitality. The objective is not to switch it off unnecessarily, but to identify inefficient operation, inappropriate settings or faults that increase energy consumption.

Lighting

Lights left on in unoccupied areas can create avoidable consumption across long overnight periods. Timers, occupancy controls and suitable operating schedules can help reduce unnecessary runtime.

Ventilation and extraction

Fans and extraction systems may continue running after the activities that require them have finished. Their schedules should reflect actual operational needs, while maintaining appropriate indoor air quality and safety.

Hot water and other equipment

Hot water systems, pumps and other equipment can operate outside required hours because of poorly configured timers or controls. Their consumption should be assessed against the needs of the building.

Prioritise investigation using actual consumption data, operating hours and equipment requirements rather than assuming the same system is responsible at every site.

How much does out-of-hours energy waste cost a business?

The cost depends on the amount of avoidable consumption, how long it continues, and the applicable electricity or gas rate.

A simple calculation can help estimate the opportunity.

For example, suppose equipment draws an average of 10 kW unnecessarily for eight hours each night, five nights a week.

• Average avoidable load: 10 kW

• Operating period: 8 hours per night

• Frequency: 5 nights per week

• Annual operating time: approximately 2,080 hours

• Potential avoidable consumption: 20,800 kWh per year

At an illustrative electricity rate of £0.25 per kWh, this would represent £5,200 in annual electricity costs.

This is an example, not a forecast of typical business savings. Actual costs will depend on the measured load, operating pattern and energy tariff. Gas consumption and other relevant charges should be assessed separately where applicable.

For a multi-site business, the same calculation can be applied to individual locations. This helps establish which opportunities deserve attention first and provides a starting point for a business case.

How can businesses stop out-of-hours energy waste from returning?

Finding waste is only the first step. Businesses also need to make sure corrective actions work and that unnecessary consumption does not return a few months later.

A practical approach includes:

• Correct schedules and setpoints: Update controls to reflect actual operating hours and requirements.

• Assign responsibility: Give each action to a named person, with a target date.

• Measure the result: Compare energy consumption before and after the change, allowing for relevant differences in weather, occupancy and trading hours.

• Monitor ongoing performance: Review energy patterns regularly to identify changes, overrides or unexpected consumption.

• Compare sites: Benchmark similar locations to identify unusual patterns and share effective operating practices.

For businesses with many locations, centralised monitoring can make this process more manageable. Instead of relying entirely on individual site visits, energy and facilities teams can review patterns across the estate and investigate sites where consumption warrants attention.

An energy management system can support this process by bringing monitoring and control information together, helping teams identify issues and manage connected equipment remotely where the installation supports it.

You can read more about how Vision iQ supports energy monitoring and control across multi-site estates.

How Clearworld can help identify out-of-hours energy waste

Clearworld helps multi-site businesses understand energy consumption across their estates, identify unnecessary usage and take action to improve building performance.

The starting point is often the data businesses already have.

Free data audit

Clearworld analyses half-hourly energy data to identify unusual consumption patterns, potential out-of-hours usage and opportunities for further investigation. Start by exploring the Vision iQ page or contact Clearworld about a data audit.

Wireless monitoring

Sense iQ collects information from connected sensors, helping businesses build a clearer picture of conditions and equipment performance across their sites. Learn more about Sense iQ.

Centralised visibility

Vision iQ brings relevant information together, allowing teams to review energy and building performance across multiple locations rather than relying on isolated site-level checks. Explore Vision iQ.

Remote control

Energy iQ supports control of connected equipment, helping businesses manage energy use in line with their operational requirements. Find out more about Energy iQ.

For businesses with an existing building management system, Clearworld's technology can work alongside the existing setup, helping address gaps in monitoring and control where appropriate. Read our guide to BMS optimisation.

The result is a more structured way to identify energy waste, investigate its cause, prioritise action and measure the outcome.

Want to understand what's happening across your estate? Speak to Clearworld about a free data audit to identify potential energy-saving opportunities in your half-hourly data.