A practical out-of-hours business energy audit for 2025

Energy use does not necessarily stop when the team goes home. This 2025 audit plan helps small businesses investigate overnight and weekend consumption without guessing which equipment is responsible.

Define what must remain on

Start with a list of essential loads. Refrigeration, security, servers, ventilation and safety systems may need to operate when the building is empty. Ask the relevant person to confirm operating requirements before changing any controls. Food safety, equipment protection and staff safety come first.

Make a second list of equipment that could follow occupancy more closely. Examples might include display lighting, office monitors or heating in an unused room. Treat each as a question to investigate, not an instruction to switch it off.

Establish a baseline week

Use meter readings or available interval data to understand a typical week. Note opening hours, unusual deliveries, overtime, weather and any equipment faults. Compare like-for-like periods: a cold Monday after a busy weekend is not necessarily comparable with a mild bank holiday.

Where interval data is unavailable, an authorised person can record the meter at closing and again before opening. The difference shows total consumption during the gap. It will not identify individual appliances, but it can reveal whether further investigation is worthwhile. Our meter reading guide is a useful starting point for organising records.

Walk the building with the right people

Ask someone from operations or facilities to explain timers, thermostats and equipment schedules. Look for controls still using an old opening pattern, zones operating while empty and lights left on after cleaning. Check whether weekend schedules differ from weekdays.

General efficiency guidance from the Energy Saving Trust provides a wider starting point. Your own measurements are what turn a general suggestion into a decision for your building.

Test one change at a time

Choose a reversible change with a clear owner. Record the original setting, the revised setting and the date. Check comfort and operations as well as consumption. If several controls change at once, it becomes harder to identify which adjustment caused a benefit or a problem.

For illustration, reducing a measured load by 0.5 kW for 12 hours on 250 days would avoid 1,500 kWh. At an assumed 25p per kWh, that is £375 in energy charges. This is arithmetic for planning, not a promised saving or a quoted tariff; standing charges would remain outside that calculation.

Turn the findings into a routine

Keep a one-page shutdown checklist with explicit exceptions for essential systems. Assign ownership of timers and review settings when opening hours change. Repeat the measurement after a few weeks, allowing for weather and activity, to see whether the improvement persists.

Reducing consumption and buying energy are separate tasks. Once you have a more reliable usage picture, our energy procurement service can help you discuss contract options using better information.