Out-of-Hours Energy Waste: Quick Wins for Smarter Building Efficiency
When it comes to improving building performance, most energy managers are focused on big-ticket items — heating, cooling, lighting, plant optimisation. But one of the easiest wins, and in our experience, the most commonly overlooked issues is out-of-hours energy waste.
In a time of rising energy costs and tightening regulations, ignoring this issue means leaving savings on the table.
What is out-of-hours energy waste?
Out-of-hours energy waste occurs when building systems, like HVAC or lighting, continue to operate outside of normal occupancy hours, often unnecessarily.
This might look like:
- HVAC systems heating or cooling empty spaces overnight
- Lighting schedules running beyond business hours
- Equipment staying powered up over weekends and holidays
- Buildings running at full set-points when only partially occupied
The cause is usually a mix of default settings, manual overrides, and poor schedule alignment. But while these may seem like minor factors, they can significantly increase unnecessary energy consumption and operating costs.
Why it matters for energy managers
For energy managers looking to demonstrate results quickly, this is a clear opportunity. We’ve seen many business portfolios where out-of-hours energy use can account for up to 20–30% of total building consumption, depending on the building type and use pattern.
Reducing out-of-hours energy wastage offers a number of benefits, including:
- Immediate cost savings, often with no CapEx
- Improved EPC scores and carbon performance
- Less stress on systems, which means fewer breakdowns and longer asset life
- Quick internal wins to help build the business case for longer-term investment in energy efficiency measures
How you can spot the waste
Start with a simple comparison of weekday vs weekend or nighttime usage. Your BEMS or aM&T (automated monitoring & targeting) platform may already hold the data.
Here are some key indicators to look for:
- High baseload usage during unoccupied hours
- Flat profiles with no drop-off after working hours
- Sites or zones that don’t differentiate between core and non-core operating hours
Even if you're using automated controls, it’s worth checking if settings are out of date — especially in multi-tenant buildings or sites that have changed usage patterns.
In the UK, a common cause of this can be when the clocks change for daylight saving time, as the BEMS set points may not have been updated to align with the altered operating hours.
How you can fix it (without spending a fortune)
1. Audit your schedules
Review BEMS settings, lighting controls, and HVAC timers. Cross-check them with actual occupancy.
2. Engage internal teams
Sometimes systems are overridden and left running manually. Awareness and simple reset protocols can go a long way.
3. Use occupancy data
If available, tie controls to real occupancy through IoT sensors or access logs. This is particularly effective in offices, retail, and education buildings.
4. Set alerts for anomalies
Many BEMS platforms allow alerts for usage spikes during non-operational hours. This helps catch issues before they become costly.
Final thought: small fix, big impact
Energy managers are often under pressure to deliver fast, visible results. Out-of-hours energy waste is one of the easiest ways to do just that — and in many cases, it doesn’t require new tech installation or capital spend.
It’s not just about turning things off — it’s about using your systems smarter. And in today’s climate, every kilowatt counts.
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Article by Gary Bark
Chief Commercial Officer
Throughout his 40 year career, Gary has developed many strategic solutions to meet client's sustainability business goals across large real estate portfolios, with extensive expertise in building energy management, as well as the integration of systems and applications that deliver true value add and business outcomes for end user clients.
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