Smart Buildings: The Reality Check on site

Keywords: EPBD; BACS; smart buildings; technical building systems; EN ISO 52120-1; SRI; inspections; indoor environmental quality; demand-side flexibility

The revised EPBD gives BACS a bigger role in everyday building operation. Building professionals now need practical ways to identify covered buildings, specify the required functions, commission systems properly and keep evidence that the installation works.

Why this matters now

The revised Energy Performance of Buildings Directive gives building automation and control systems a stronger role in Europe’s building stock. In many non-residential buildings, BACS will increasingly be part of the expected technical infrastructure for managing energy use, indoor conditions and system operation. [1][2]

For building professionals, the discussion is no longer abstract. Owners, designers, installers, facility managers and inspectors need to answer practical questions. Which buildings are covered? Which functions are required? What should be checked during commissioning? What records should remain with the owner? Who acts on alarms, trends and performance information after handover?

These questions matter because weak operation is still common in everyday buildings. Heating and cooling can operate at the same time. Ventilation schedules can be outdated. Setpoints drift. Alarms are ignored. Energy use increases without a clear explanation. In many cases, the problem is not the absence of efficient equipment, but the lack of good visibility, control and follow-up.

Well-designed and well-commissioned BACS help building managers see what is happening and make better operational decisions. The revised EPBD increases the need for these capabilities to be specified, installed and verified in a consistent way.

Figure 1. BACS as the coordination layer for building systems.

The 70 kW threshold

One of the most important changes is the wider scope of the BACS requirement.

The EPBD already covers large non-residential buildings with a rated output above 290 kW. The revised Directive goes further. By the end of 2029, all non-residential buildings with heating, air-conditioning, combined heating and ventilation, or combined air-conditioning and ventilation systems above 70 kW will need BACS, where technically and economically feasible.[1]

This is a big step for the market. It brings many more normal buildings into the discussion: schools, hotels, public buildings, medium-sized offices, retail spaces and mixed-use buildings. These buildings often have less technical support than large commercial assets. Documentation may be incomplete. Facility management may be outsourced. The original commissioning records may be difficult to find.

That makes the first check very important: is the building covered?

That requires a clear view of the technical systems, their rated output and the available records. Owners need to know which equipment is counted and how the calculation is made. Designers, installers and inspectors need the same interpretation, otherwise similar buildings may be treated differently.

A practical scope check will be one of the most useful tools for national implementation.

Economic feasibility should not become a general exemption from the BACS requirement. The Commission guidance treats feasibility limits as exceptions that should be clearly framed, justified and assessed through defined procedures, rather than left to broad interpretation [2]. France provides a useful example: the BACS rules allow an exemption only where the owner produces a study showing that installation is not achievable with a payback time below ten years, with the calculation method set in national rules [6].

Figure 2. Scope check for non-residential buildings under the EPBD BACS requirement.

Check functions, not gadgets

Smart building compliance can easily become too focused on equipment. A dashboard, sensor network or communication protocol may be useful, but only if the underlying functions are present and usable. For BACS compliance, the key functions include monitoring, logging, analysing and allowing adjustment of energy use. The system should help benchmark performance, identify losses in efficiency, inform the person responsible for the building and communicate with connected technical building systems.[1][3]

A functional approach gives room for different technical solutions. A school, hotel and hospital will not have the same system design. The required level of complexity, risk and operational support will also differ. The common element is the ability to demonstrate the required functions. In practical terms, building professionals should be able to answer basic operational questions. Can the main energy uses be monitored? Are schedules and setpoints visible? Can they be adjusted? Can the system show faults or inefficient operation? Are alarms and trends useful for the person operating the building? Can the main technical systems exchange information? Has the system been commissioned against the intended functions?

Commissioning deserves particular attention. A BACS installation can look complete while schedules, alarms, user access, trend logs or integration points remain poorly configured. The owner then receives a system that is installed, but not properly usable. Good specifications should therefore describe the expected functions clearly. Good commissioning should check that they are delivered. Good handover should make sure the owner knows how to keep them working.

Figure 3. Core BACS functions to be demonstrated.

Evidence for owners and inspectors

Most building owners do not want another compliance folder sitting unread on a shelf. They do, however, need enough information to show what has been installed and how it works.

A useful evidence file can be relatively simple. It may include an equipment list, rated output calculation, design notes, commissioning records, BACS screenshots or exports, trend logs, alarm records, operation and maintenance manuals, and confirmation of who is responsible for system operation. These records help avoid different interpretations later. The owner can show whether the building is in scope. The installer can show which functions were delivered. The inspector can check the installation against a consistent set of documents. Public authorities can build national guidance around evidence that already exists in normal projects.

The eu.bac BACS Compliance Verification Checklist follows this practical logic. It helps structure the process for owners, designers, installers, assessors and inspectors: identify the building, check the system scope, confirm the required BACS functions and review the supporting records. The file does not need to be perfect. It needs to be usable. A person inspecting the building should be able to understand what is installed, what it is supposed to do and where the evidence can be found.[4][5]

The point is not to create a perfect file. The point is to make compliance checkable.

Where standards help

The EPBD gives the legal basis for BACS requirements. Building projects also need technical language that can be used in specifications, checklists, training and inspection. EN ISO 52120-1 is an important reference for this work. It describes the contribution of building automation, controls and technical building management to the energy performance of buildings. It gives professionals a structured way to talk about functions for heating, cooling, ventilation, lighting, shading and technical building management.[2][3][4]

That common language helps reduce vague claims about “smart” systems. It also helps designers, contractors, assessors and authorities focus on functions that can be designed, installed and checked.

The Smart Readiness Indicator is also relevant. BACS compliance and SRI assessment serve different purposes, but both rely on a good understanding of the building’s technical systems. Evidence collected for BACS compliance can support SRI assessment, and an SRI assessment can help owners identify improvement options beyond minimum compliance. The same building should not need several separate evidence exercises for closely related checks. Once SRI gets rolled out across the EU, where possible, BACS compliance, SRI assessment and technical building system inspections should draw on a shared set of building records and operational data.

Figure 4. Common evidence base supporting BACS compliance, technical system inspections and SRI assessment.

Better control in a changing building stock

BACS should be seen in the wider context of building operation. Good controls reduce wasted energy, make faults visible and support indoor environmental quality. They also give facility managers a clearer picture of how the building reacts to weather, occupancy and user needs. This operational role is becoming more important. Heatwaves are increasing cooling needs. Hybrid working has changed occupancy patterns. Energy prices are more visible to owners and tenants. Electrification brings more heat pumps, solar PV, storage, electric vehicle charging and controllable loads into buildings.

All of these trends increase the value of good control. A building cannot provide useful demand-side flexibility if its systems are not visible, connected and manageable. It cannot maintain good indoor conditions efficiently if schedules and setpoints are outdated. It cannot improve performance if nobody can see where problems occur.

BACS therefore support more than EPBD compliance. They are part of the practical infrastructure needed for efficient, flexible and resilient buildings.

What national guidance should cover

Member States have flexibility in how they transpose and implement the EPBD. The building market will still need clear guidance to apply the rules consistently. National implementation should explain how to determine whether a building is in scope, how to assess technical and economic feasibility, which BACS functions are required, what evidence owners should keep, who verifies compliance and how BACS requirements link with inspections, energy performance certificates and SRI assessments.

Clarity is especially important for the 70 kW threshold. Many newly covered buildings will not have large technical teams. Owners and facility managers will need simple guidance and practical examples. Inspectors will need a consistent basis for checking installations. Designers and installers will need requirements that can be translated into specifications and commissioning tasks. Good implementation should be realistic for ordinary buildings while still being robust enough to avoid loopholes.

The job for the sector

The revised EPBD now needs to be translated into project routines: clear specifications, proper commissioning, useful handover records and practical verification.

For designers, that means specifying functions rather than vague “smart building” features. For installers and system integrators, it means proving that the functions work. For owners and facility managers, it means keeping records and using the information the system provides. For inspectors and authorities, it means checking compliance in a consistent and proportionate way.

The building should be able to show that the required BACS functions are present, usable and maintained. That is the practical test. If the sector gets this right, BACS can help reduce the gap between design intent and daily operation. If implementation remains unclear, Europe risks more buildings that look compliant in documents but underperform in use.

Smart buildings now need to prove it on site.

References and further reading

[1]     Directive (EU) 2024/1275 of the European Parliament and of the Council of 24 April 2024 on the energy performance of buildings (recast), especially Article 13, Article 15/Annex IV, Article 16 and Article 23. https://eur-lex.europa.eu/legal-content/EN-CS/ALL/?from=EN&uri=CELEX%3A32024L1275

[2]     European Commission, Energy Performance of Buildings Directive - implementation information, support package and EPB standards overview. https://energy.ec.europa.eu/topics/energy-efficiency/energy-performance-buildings/energy-performance-buildings-directive_en

[3]     EN ISO 52120-1 / ISO 52120-1: Energy performance of buildings - Contribution of building automation, controls and building management - Part 1. https://www.iso.org/obp/ui/en/#iso:std:iso:tr:52120:-2:ed-1:v1:en

[4]     CEN/TR 18276:2026, Checklist of compliance of building automation with EPBD requirements. https://app.nbn.be/data/r/platform/frontend/detail?lang=nl&p40_id=3497048&p40_language_code=nl

[5]     eu.bac, 2024 EPBD BACS Compliance Verification Checklist and related EPBD BACS guidance. https://eubac.org/news/eu-bac-updates-its-bacs-compliance-verification-checklist-to-match-the-reviewed-2024-epbd/

[6]     France, Code de la construction et de l’habitation, Article R.175-2, and Arrêté du 7 avril 2023 relatif aux systèmes d’automatisation et de contrôle des bâtiments tertiaires, setting the exemption and payback calculation method for the French BACS requirements.