BUILDING ENERGY MANAGEMENT SYSTEMS
Rethinking BMS and EMS for modern buildings
While a BMS gives you control over your building’s operations, an EMS provides the insight to cut energy waste and costs. Clive Bodenham argues that the real value comes when the two work together.
Clive Bodenham
www.clarke-controls.co.uk
Founder of Clarke Controls
W An energy management system
hile on a site visit the other day, I was asked an interesting question which should be of interest
to managing directors and facility managers reading this: Do you need a Building Management System (BMS) or an Energy Management System (EMS)? On the surface, it sounds straightforward – but the more you dig into it, the more complex it becomes. Let’s unpack it.
BMS vs EMS: What’s the diff erence? Both systems aim to make buildings more efficient and reduce energy waste, but they serve slightly different purposes.
A building management system
(BMS) is all about control. It automates and manages heating, ventilation, air conditioning, lighting and sometimes even security. Instead of relying on outdated time clocks or manual thermostats, a BMS reacts to real- world conditions – switching things on and off depending on occupancy, weather and operational patterns.
BMS advantages: ● Comprehensive control across an entire building
● Can integrate with existing infrastructure
● Flexible enough to work with mixed or older systems
EIBI | OCTOBER 2025
(EMS) on the other hand is primarily about monitoring and optimisation. It focuses on a specific challenge – for example, heating across multiple commercial premises – and gives energy managers the visibility and insight needed to cut waste, save money and reduce emissions (a critical part of the equation with increasing regulation set to come in).
EMS advantages: ● Purpose-built to tackle a specific problem, i.e. heating efficiency
● Scalable across sites and locations ● Lower entry cost than a full BMS So, back to the question: Do you need a BMS or an EMS? The best answers come from the best questions. So let me pose this question instead: Do you want strawberries or cream? The obvious answer is both – because they work best together! At Clarke Controls, that’s exactly
how we’ve designed our EMS. It combines the control typically associated with a BMS with the monitoring and optimisation of an EMS. That means you don’t have to choose – you get the best of both worlds, without unnecessary cost or complexity.
Why it matters
Heating is still the single largest energy expense in most non-domestic buildings, accounting for 50–75% of total consumption. Yet it’s often the least well-managed, with systems left running regardless of whether spaces are occupied or needed. The result is wasted energy, higher bills, and frustrated building users.
Our EMS tackles these challenges
directly by allowing you to: 1. Zone and schedule heating by demand – heating only the spaces that are in use
2. Control remotely – cloud dashboards let you make changes instantly from anywhere
3. Respond to real-time conditions – for example, pausing heating when external doors are open or adapting to holiday schedules
4. Track usage and detect waste – live data highlights faults and inefficiencies before they become costly problems
Real-world impact Take one of our clients as a case study. Based in a large open-plan factory in the North of England, their traditional gas-fired heating was expensive and poorly controlled. We installed a Clarke Controls EMS, dividing the space into zones and tailoring heating to shift patterns. Within four months, the site saved 280,000 kWh – equivalent to £28,000 – and cut emissions by 20%. The previously regular complaints about heating
Clarke Controls specialise in providing full tailored controls systems for OEMs and operators across various industries
stopped and the system paid for itself in just six months. As more buildings move to
low-carbon heat sources, an EMS becomes even more valuable. These technologies often require precise control to operate efficiently and avoid high running costs. They can:
● Optimise energy use to avoid unnecessary electricity demand
● Schedule hybrid systems to favour renewable sources
● Record performance data for fine- tuning and future-proofing
Why now? Energy prices may fluctuate, but the long-term trend is clear: tighter regulation, greater accountability and rising expectations for sustainability. Facilities teams are under pressure to cut costs, reduce carbon, and deliver consistent comfort – often with fewer resources. That’s where Clarke Controls
A BMS will bring you the control you need, while an EMS will help optimise your heating and energy costs
comes in. Our EMS doesn’t just monitor – it controls. It gives you the tools to save money, reduce emissions, and future-proof your operations – with minimal disruption and rapid payback. So, do you need a BMS or an
EMS? The truth is, ideally, you need the benefits of both as they are complementary systems. A BMS will bring you the control you need across your building, while an EMS will help optimise your heating and energy costs, reducing your bills and carbon footprint by up to 25%. ■
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