Buildings account for 40% of the EU’s energy consumption — and BACS is the solution

Buildings are the EU’s largest single consumer of energy. According to the European Commission, 40 percent of the EU’s total energy consumption comes from buildings — and 75 percent of these buildings are not energy-efficient. Building Automation and Control Systems (BACS) are the proven tool for reducing energy consumption by up to 30 percent, with a payback period of under five years.

The energy problem of buildings in numbers

40 percent of the EU's total energy consumption comes from buildings — more than industry and transport combined in many cases. 32 percent of the EU's total energy consumption is specifically used for HVAC (heating, ventilation, and cooling) and lighting — precisely the systems that BACS controls and optimises.

85 to 95 percent of the buildings that exist today are expected to still be standing in 2050, when the EU's climate neutrality targets are to be met. The solution is not to demolish and build new – it must be realised through the retrofitting of existing buildings. And the most cost-effective way to improve energy efficiency in existing buildings does not always involve replacing facades or adding insulation. It involves intelligent control of the installations that are already there.

What can BACS actually save?

Up to 30 percent energy saving — documented

Studies supported by EU-BAC (European Building Automation and Controls Association) show that buildings with integrated BACS can achieve energy savings of up to 30 percent compared to buildings without intelligent control. This is a potential that has been documented in practice in existing buildings – offices, hospitals, educational institutions and industrial facilities.

The mechanisms behind the savings are well-documented: demand-controlled ventilation and heating based on actual room occupancy; elimination of energy waste in unused zones; integrated control of solar shading that coordinates cooling and solar incidence; and proactive rather than reactive operation based on weather forecasts and planned occupancy.

HVAC: The largest single item

HVAC – heating, ventilation and air conditioning – accounts for 47 percent of a typical office building's energy consumption. When BACS optimises HVAC operation, this is where the savings are greatest. Even a 20 percent reduction in HVAC consumption in a medium-sized office building can equate to savings of DKK 100,000 to DKK 300,000 per year.

Lighting: The low-hanging apple

Lighting typically accounts for 15 to 20 percent of an office building's energy consumption. With demand-controlled lighting – automatic regulation based on presence and daylight – lighting consumption can be reduced by 30 to 60 percent. In many cases, it is possible to integrate existing lighting systems with the DALI-2 protocol and intelligent sensors as a retrofit.

The regulatory driver: EPBD and BACS requirements

The EU's Energy Performance of Buildings Directive (EPBD) sets direct requirements for the installation of BACS (Building Automation and Control Systems) in non-residential buildings via Article 13:

An old BMS system that simply starts and stops systems according to schedules does not meet the EPBD requirements. The directive requires active monitoring, analysis, and documentation – not just control.

Retrofit: The reality for 85-95 percent of buildings

A BACS retrofit is about adding intelligence to existing technical installations without necessarily replacing them. It can typically include gateway integration of existing systems, sensor systems for temperature, CO2 and occupancy, a central BMS control system and intelligent room control per zone.

The accounts: Business case for BACS

For an office building of 4,000 m² with a typical energy consumption of 100 kWh per m² per year and an average energy price of DKK 2.00 per kWh, the calculation looks like this:

With rising energy prices – which is the expected trend – the payback period becomes even shorter. When you add the value of ESG documentation, reduced operating costs, and potentially higher property value, the overall business case is even stronger.

BACS as a Data Source: From Compliance to Insight

A modern BMS is not just a control system – it's a computer. Continuous collection and analysis of energy data, operational data, and indoor climate conditions create a knowledge base for ongoing optimisation. Modern BMS systems automatically generate periodic energy reports and can identify abnormal consumption via alarms to those responsible for operations.

For building owners with ESG commitments, BACS is in practice indispensable. It is the system that provides the ongoing, verifiable documentation for energy consumption and CO2 savings, which is required for sustainability reports, for CSRD reporting, and for certifications such as BREEAM, LEED, and GRESB. Without BACS, one is reliant on manual measurements, estimates, and sample checks.

Frequently asked questions

How much energy can BACS save?

Studies supported by EU-BAC document that buildings with integrated BACS can achieve energy savings of up to 30 percent compared to buildings without intelligent control. In practice, the specific potential depends on the building's age, existing installations, and the ambition level of the solution.

What does the EPBD require of building owners?

EPBD Article 13 requires BACS in non-residential buildings with installations above 290 kW from 31 December 2024, and in buildings with installations above 70 kW from 31 December 2029. From 29 May 2026, monitoring of indoor climate conditions will also be required. The requirements are implemented in Denmark via the Building Regulations.

What is the payback period for a BACS investment?

For a typical office building of 3,000 to 5,000 m², the payback period for a BACS investment is typically 3 to 5 years based on energy savings alone. With rising energy prices and factoring in ESG documentation value and reduced operational costs, the actual payback period could be shorter.

Can BACS be installed in existing buildings?

Yes. A BACS retrofit adds intelligence to existing installations via gateways and sensors without necessarily replacing the existing systems. Open standards such as BACnet, KNX, Modbus, and DALI enable integration with most existing systems. A site assessment can identify precisely what can be reused and what is minimally required for EPBD compliance.

What's the difference between BACS and a standard BMS?

An old BMS starts and stops systems according to fixed schedules. An EPBD-compliant BACS continuously monitors, analyses and documents energy consumption, benchmarks efficiency, identifies energy losses and ensures interoperability across building systems. EPBD sets specific functional requirements – a simple time-clock-controlled system does not meet them.

Sources

• European Commission Energy Performance of Buildings Directive (EPBD) – Directive 2024/1275, Article 13. eur-lex.europa.eu
• EU-BAC (European Building Automation and Controls Association): Documentation on energy saving potential for BACS. eubac.org
• EN ISO 52120: Standardised Building Automation and Control
• Build Up – European Portal for Energy Efficiency in Buildings. build-up.ec.europa.eu