Building Energy Management for Better Business Sustainability

Energy waste is everywhere in businesses and the public sector. Fans are often left on after there’s no one in the office, and ventilation systems run for empty rooms. To combat this, many companies invest in a building energy management system (BEMS). 

These systems monitor how you use gas and electricity and look for ways to cut back without affecting business operations.

In this article, you will read about BEMS and the components that make up these systems. You will also learn their four-step process. 

Discover the environmental gains you’ll make and how to set up a scalable solution in your organisation, with insights provided by Professor Jacopo Torriti, Professor of Energy Economics and Policy at the University of Reading.

The Carbon Trust defines a BEMS as a system that monitors and optimises energy use across building services. It does this by controlling heating, cooling, ventilation, hot water, and lighting systems. 

A BEMS also manages plant and equipment, the fixed mechanical and electrical kit that runs a building (e.g., boilers and air handling units). This helps companies use less energy without affecting output or staff comfort.

A typical BEMS contains the following components:

Meters and sensors measure:

• Electricity, gas, and heat usage
• Temperature, humidity, and CO₂ levels
• Occupancy and motion

This gives businesses a live view of energy use and building conditions, rather than relying on delayed or incomplete reports.

Panel or plant-room devices run the control logic next to the equipment. Control logic is the set of rules that decides how and when systems operate.

They start and stop plant machinery, modulate valves and fans, and apply interlocks to avoid waste. For example, they stop heating and cooling systems from running at the same time, a common cause of unnecessary energy use.

Each controller also stores its company’s default settings safely. If there’s a fault or network interruption, the BEMS or local unit falls back to these settings. This means core systems keep running even if the central server goes offline.

Energy management system software, like a BEMS, receives the live data from a system's meters and sensors. It also enables managers to perform the following:

• Run times and performance levels: Schedule when equipment operates and define target values. For example, that could be DHW at 60°C or lighting at 300 lux
• Alarm notifications: Receive alerts when there's an issue, like a sensor reading that’s out of range
• Remedial task setting: Upon receiving an alert, assign a remedial task to colleagues and set its priority level. Managers can then track work all the way through to completion
• Comparisons: Compare buildings side by side on the same screen. Managers can examine factors, including end use (e.g., HVAC), zone (e.g.,  first floor), and time (e.g.,  last month). This helps teams focus first on the biggest savings, such as high out-of-hours energy use at a site
• Report building: Managers can also access detailed data for reports on factors like interval meter data and event logs. This is useful for energy and carbon reporting (SECR) and internal environmental, social, and governance (ESG) packs

As HVAC is often the biggest slice of a commercial building’s energy use, let’s use this as an example to show how a BEMS operates.

A BEMS constantly checks a site's environmental performance. It does this by collecting key metric data, such as room temperatures, humidity, and air quality. It also keeps records of whether major plant equipment, like fans, pumps, and boilers, is running as expected.

These systems can monitor electricity use across all key circuits, not just the whole-building meter. They can look into the data to pinpoint specific causes of waste, like high base loads and out-of-hours consumption.

A BEMS also improves system performance by using outside data to refine its control decisions. This can include occupancy schedules and weather forecasts. Extra context helps to build a more complete and accurate picture of how to control energy use more effectively.

After analysing the data, the BEMS then decides on the best energy management strategy.

For example, the system may pre-heat a given space because occupancy data tells it a meeting has been booked there. It makes sure the room is ready for attendees, but that the system doesn’t run longer than necessary.

Another way it can cut energy use is by reducing fresh-air intake when CO₂ levels stay below target in low-occupancy zones.

Once it decides on the best approach, the BEMS then sends precise commands to specific building systems equipment. It can start, stop, or adjust operation in fine steps to deliver the required result using the least energy possible.

Modern BEMS instructions go far beyond the simple on/off switches and thermostats of legacy systems. They make ongoing adjustments to achieve the desired outcome. That includes modulating fan speed, boiler output, and the position of valves in air ducts and heating/cooling pipework.

Finally, the BEMS learns from its own performance. It compares data to measure actual energy use and system behaviour against anticipated targets.

It looks for ways to perform better, developing strategies to deliver optimal performance. For example, it can learn how long a building takes to heat up on colder mornings to reach its target temperature by the start of the workday.

Over time, it can finesse this further by developing settings for precise outside temperatures. For example, it may start heating at 06:30 on a cold January morning, but at noon, it would delay heating or reduce output to avoid overshooting.

The environmental and financial benefits BEMS offers companies and governments can be significant. Here are some of the latest statistics:

• Croydon office: After BMS optimisation, one office cut whole-building energy use by 28%. In just nine months, the site saved £171,000 and avoided 232 tonnes of CO₂ emissions
• UK government department: A large, public department rolled out BMS upgrades across 47 sites. The pilot phase alone saved £75,300 in energy costs (1.8GWh) and prevented 350 tonnes of CO₂ emissions
• AI-powered digital twin: A case study using AI and digital twin modelling showed 30% savings in electrical energy and 42% in thermal energy. Likewise, CO₂ emissions fell by 24% and 34%, respectively

Implementing a BEMS successfully is a step-by-step process. The most effective deployments start small with a clear purpose and dedicated team on a pilot site.

First, choose a building to host your trial. Retune timer settings, holiday calendars, temperature bands, and any heating and cooling clashes. This alone can deliver savings of between 5% and 25%, according to the U.S. Department of Energy.

These are the next steps:

Select an open connection standard for your system, such as BACnet or Modbus. This is the method by which data is transferred from the local controllers to your software. Using an open standard increases the likelihood of your current systems being compatible.

Give each connection point a name so you can track usage on the dashboard. Test each one to make sure you're getting accurate readings.

This set-up also adds resilience to your organisation. The local connectors keep on working even if a cloud or internet connection goes offline. The schedules you've set for your system will still apply, and the server will store settings for later analysis.

Input your last 12 months of bills, paying attention to total kWh, out-of-hours kWh, and peak kW. By matching the UK’s SECR reporting requirements, your finance team can include energy management efficiency data in annual reports. 

This is important because it saves time and means you don’t have to collect the same data twice. You can also use the latest DESNZ conversion factors to turn energy data into CO₂e for carbon reporting or internal tracking.

You can set up a test to make sure that settings don't impact comfort and air quality. Track the percentage of hours each space stays within a target:

• Target temperature band (e.g., 20–24°C)
• CO₂ band (e.g., below 1,000 ppm)

This way, you'll be able to determine that your energy savings haven't come at the cost of worse workplace conditions.

Many sites only have a whole-building meter. If that's the case at your site, install separate sub-meters for the largest use sources of electricity.

This should include your air conditioning, lighting systems, and hot water systems. You can then isolate base loads from individual systems and equipment, as well as track out-of-hours use.

Without this setup, it's hard to prove that the settings on your BEMS are actually leading to reduced energy waste. You'll also struggle to see what's driving consumption, making cutting energy costs much harder.

Demand-controlled ventilation (DCV) is a key feature in many smart buildings. It increases fresh air when CO₂ or occupancy levels rise and reduces it when spaces are quiet.

This keeps air quality within target while cutting energy usage from fans, heating, and cooling. According to the National Energy Renewable Laboratory, DCVs lead to cost savings of:

• 8.8% for heating gas
• 9.3% for heating electricity
• 2.1% for cooling electricity

When feedback from your meters and sensors is accurate and reliable, switch on the analytics function in your BEMS. An energy information system (EIS) and fault detection and diagnostics (FDD) system help identify issues before they lead to waste. These issues can be:

• Stuck dampers: Letting in too much or too little air, which throws off heating or cooling
• Drifting sensors: Slowly reporting the wrong readings, leading to poor decisions
• Creeping schedules: Equipment running longer than needed because timers weren’t reset

An EIS can lead to a 3% saving in energy costs, while FDD systems can produce 9%. According to Berkeley Lab, the payback period on the systems can be as little as two years.

Peaks are the short windows when sites pull the most power. They often cost a lot more because firms draw the electricity at busy times, which is what pushes up bills.

There are ways to plan for peaks with a BEMS:

• Stagger your starts: Don’t let everything fire up at 08:00. Sequence fans, pumps, and chillers so loads ramp up smoothly and avoid a spike. This is a standard BEMS control and a core part of grid-interactive, efficient buildings
• Cap the site peak: Decide on a KW ceiling for a building. If it looks like you're about to shoot over, program the BEMS to pause non-critical kit for a few minutes. That could be a secondary pump or a supply fan. When usage is heading back down, allow the non-critical kit to start working again
• Smart use of time tariffs: Load up on power during off-peak periods and release it when you need it. This cuts costs and reduces your dependence on the National Grid. This can be particularly productive if you have battery energy systems on-site. Explore our range of power transformers and power supplies built to support them

Building energy management is set to undergo further improvement with the addition of AI analytics. Position your firm to take advantage of the financial, reputational, and ESG benefits of energy conservation.

Explore our sustainable technologies hub for ideas. Also check out our renewable energy categories for meters, sensors, and controllers, and read our renewable energy guide for on-site options.