Energy management systems (EMS) are used by businesses to improve their energy efficiency, helping minimise unpredictable business electricity prices and meet tightening compliance requirements on energy efficiency and carbon emissions.
This article explains how an EMS works, what it typically includes, and how to determine the right system for a business.
What is an energy management system (EMS)?
An energy management system (EMS) combines software, hardware and a management framework to optimise a business’s energy use, and its associated cost and carbon emissions.
It can be as simple as a small business shifting energy usage to lower-cost times using smart meter data, to a fully AI-driven system that optimises power usage, generation and storage across a large site.
Regardless of complexity, an EMS establishes a starting baseline, monitors energy flows, analyses patterns, and applies changes to optimise energy usage.
It relies on three elements working together:
- Managers: Facilities or sustainability leads who set energy targets, interpret reports, and sign off on recommendations.
- Hardware: Meters, sensors, and control devices that gather consumption data and act on commands, such as switching equipment on/off or adjusting output.
- Software: The platform that processes raw data into meaningful insights for stakeholders, while also running the logic that drives automated controls.
EMS implementations revolve primarily around electricity and gas consumption, since these carry the highest cost and compliance weight for businesses, yet some extend this to other utilities such as water where meters and sensors are available.
When offered as-a-service by a third party, an EMS is often referred to as an Energy management solution.
How does an energy management system work?
Regardless of scope and complexity, any EMS follows a continuous cycle of data collection, analysis, and control, usually refining itself as more information comes in. This process works as follows.
1. Energy data collection
In its simplest form, meters at each mains connection (MPAN for electricity, MPRN for gas) provide usage and export data across a premises that can be used to optimise energy usage.
Smart meters are the most useful, as they collect data often and in digital form, particularly half-hourly meters, which are already mandatory for larger non-domestic consumers.
More comprehensive systems need sub-meters installed across the site to capture energy flows.
This can include anything that utilises, generates or stores power, but typically prioritises systems of the highest load to the business, such as:
- Lighting and device circuits
- HVAC (Heating, Ventilation, and Air Conditioning) systems
- Production lines
- Refrigeration
Sensors can also track related variables like temperature, occupancy, or humidity. These help explain consumption patterns and can trigger automated controls, such as an HVAC responding to occupancy.
All data typically feeds to a central EMS platform through wired or wireless connections. Multi-site businesses can consolidate data from across locations.
The more granular this data collection, the more precisely the EMS can later pinpoint where energy is being wasted.
2. Data baselining, normalisation and analysis
The EMS needs a baseline point to measure improvements against. This is typically done over a representative period, usually a full year, so that seasonal variation is captured.
This raw energy data then needs to be normalised against reference variables to ensure it is put into the right context. For example:
- Weather impacts HVAC energy use and solar panel generation. For example, lower gas usage in a milder winter isn’t necessarily a sign of efficiency, it may simply be the weather.
- Production output or occupancy levels, which impacts energy usage.
- Working days and shift patterns, as this affects time-of-use energy costs.
With a baseline and normalised data in place, the EMS platform can start identifying patterns and anomalies, such as:
- Equipment left running outside of operating hours.
- Gradual drift away from expected consumption levels.
- Correlations between energy use and other variables, such as temperature and humidity.
The stages of baselining, normalisation and analysis are required for both ESOS compliance and Streamlined Energy and Carbon Reporting where businesses need to meet compliance requirements.
3. Applying controls and optimisation
Having identified where energy is being wasted, the system applies changes, either automatically or through manual intervention:
- Automated control (Smart buildings): The EMS software directly adjusts connected equipment (HVAC, lighting, refrigeration) based on rules or logic, e.g. reducing heating when occupancy sensors show a space is empty.
- Manual intervention: Managers act on recommendations that the platform surfaces, such as scheduling maintenance on underperforming equipment, or comparing business electricity tariffs based on usage patterns.
- Demand-side actions: Shifting flexible loads (e.g. batch production, EV charging, battery storage) to cheaper or lower-carbon periods.
4. Continuous improvement
The EMS continuously tracks the effect of each change and feeds this back into the system.
Regular reports are generated for facilities managers, finance teams, or compliance officers, showing consumption trends, cost savings achieved, and any recurring inefficiencies.
Many platforms also support benchmarking against previous periods or similar sites, making it easier to judge whether interventions are working or need adjusting.
This energy audit stage is repeated regularly, with each review cycle sharpening the baseline and highlighting new opportunities for savings.
What is included in an Energy Management System?
An EMS varies in scope, and can be as simple as a meter, a spreadsheet, and a manager shifting energy use manually, to a fully automated system.
The table below sets out the core components and shows how each one can range from a basic setup to a more advanced one, giving a feel for just how differently an EMS can be built depending on a business’s needs.
What does an energy management system look like in practice?
In practice, an EMS looks different depending on the size and nature of the business, since the components and level of automation are usually matched to what each site actually needs.
- Office buildings: Sensors track occupancy and daylight levels, automatically dimming lights or adjusting heating and cooling in empty meeting rooms and after-hours areas.
- Manufacturing sites: Sub-meters monitor individual machines or production lines, flagging equipment that draws excess power or runs outside scheduled shifts, which often points to maintenance issues before they cause downtime.
- Retail units: Systems focus on refrigeration, lighting, and HVAC, since these typically account for the bulk of energy spend, with alerts sent if a fridge unit or air conditioning system drifts outside its normal range.
- Hospitality and multi-site businesses: A central dashboard consolidates data across several locations, allowing head office to compare performance between sites and identify which locations are underperforming on efficiency.
What are the benefits and limitations of an EMS?
An EMS brings real, measurable advantages, but it isn’t the right fit for every business, and it comes with trade-offs worth understanding before investing.
Benefits of an EMS
The direct benefits of an EMS are mainly financial, with indirect benefits including compliance, and commercial opportunity. These are:
- Reduces energy waste: An EMS identifies and fixes energy inefficiencies. For example, equipment left running outside operating hours, faulty timers, and poorly calibrated HVAC systems are common sources of unnecessary consumption.
- Flags equipment faults early: Machinery and building systems typically draw more power as they degrade before they fail outright. An EMS surfaces this drift in advance, giving businesses time to schedule repairs rather than deal with unplanned downtime.
- Satisfies regulatory requirements: An EMS generates the baseline and monitoring data required by ESOS and SECR.
- Meets procurement requirements: Public sector tenders and an increasing number of corporate supply chains require bidders to demonstrate environmental credentials as a condition of eligibility. An EMS provides the evidence needed to qualify.
Limitations of an EMS
While some sort of EMS is always beneficial, it can have real constraints that need to be taken into account:
- Return on investment varies by business: Where energy costs represent a small proportion of overall spend, the cost of installing sub-meters, sensors, and software can outweigh the savings achieved.
- Requires ownership to be effective: The system generates reports and alerts, but someone within the business needs responsibility for reviewing them and acting on the findings.
- Savings diminish over time: The largest gains, correcting obvious waste and installing basic controls, are typically realised within the first years. Further reductions require larger investments for smaller returns.
- Accuracy depends on maintenance: Sensors and meters degrade over time, and software requires updates. Without ongoing maintenance, the data an EMS produces can become unreliable.
How to decide what your business needs in an EMS
The appropriate EMS depends on a business’s size, energy spend, and obligations. The following factors help determine whether investing in an EMS is appropriate for your organisation.
Energy spend as a proportion of costs
A useful starting point is to look at energy as a percentage of total operating costs.
A professional services office where energy is 1-2% of costs may only need basic monitoring to catch obvious waste, timers, unnecessary out-of-hours use, and little else.
By contrast, energy-intensive industries such as manufacturing, cold storage, hospitality, and food production often see energy at 10-20% or more of costs, where even a 5% reduction can have a meaningful impact on profitability.
Regulatory obligations
Some businesses need a system capable of producing an accurate baseline and ongoing monitoring data as a legal requirement, with financial penalties for non-compliance.
This applies to those in scope for:
- SECR: UK quoted companies of any size, plus large unquoted companies/LLPs meeting two out of the following three conditions: £36m+ turnover, £18m+ balance sheet, or 250+ employees.
- ESOS: Broadly 250+ employees, or over £44m turnover and £38m balance sheet.
Businesses below these thresholds have more freedom to choose a setup.
Number and complexity of sites
A single small site with straightforward energy use, such as a small office or a shop, can often be managed using the free online monitoring tool most business energy suppliers provide as standard, reviewed monthly.
We also offer a 30 day free trial access to our Connect Hub energy platform that consolidates energy data across multiple locations and supply points.
Growth and investment plans
Starting an EMS early reduces costs in the long term for businesses looking to scale.
Retrofitting infrastructure later is more expensive than installing it upfront, and shifting a company’s culture towards energy awareness becomes harder the larger the business gets.
The impact of an EMS also becomes more significant with scale, so the earlier it’s embedded, the more value it captures as the business grows.
Access to capital
Setting up an EMS has upfront costs, which can range from hundreds to tens of thousands of pounds, depending on the scale and complexity of the system.
This budget is key in determining the scope of the EMS rollout, which can be gradual when budget is constrained.
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