Deadline pushed back to 1 January 2030 for buildings between 70 and 290 kW: the BACS decree (French decree 2020-887 on building automation and control systems) deadlines are moving. The NF EN ISO 52120-1 standard remains the reference that structures BMS classes into four levels. Understanding these levels is a decisive tool for anyone managing a commercial building portfolio. This article details each BMS class, separates the standard, the decree and the CEE energy-savings certificate scheme, and gives a practical guide to diagnosing the actual class of your building management system.
Building management systems and the 4 classes of NF EN ISO 52120-1
What is a BMS and what is the classification for?
A BMS (building management system, called GTB in France) is the system that supervises and controls the HVAC, lighting and domestic hot water (DHW) equipment of a commercial building. Its role: control setpoints, track energy consumption and ensure comfort. The NF EN ISO 52120-1 standard classifies these functions into four levels (A, B, C, D) to measure the degree of automation and its impact on energy efficiency. This classification determines compliance with the BACS decree and eligibility for CEE standardized sheet BAT-TH-116. Two separate logics, often confused.
From EN 15232 to NF EN ISO 52120-1: what changed
NF EN ISO 52120-1, published in 2022, replaces EN 15232. The four-class structure (A, B, C, D) is kept. The energy impact factors have been refined by building type, and the standard is now international (ISO). For professionals, the reading stays the same: each class describes an increasing level of automation. What changes are the calculation coefficients and European harmonization. This reference is the foundation on which both regulation and funding schemes rely.
Class D BMS: no automation
Class D is level zero. No automatic control, no dashboard, no consumption tracking. Controls are manual: an operator switches on, switches off, adjusts. The BMS is absent or disabled. This level serves as the lower reference in the standard's calculations. Comparing a class A building with a class D building quantifies the theoretical savings potential. No building should stay in class D if a BMS is installed.
Class C BMS: standard control
Class C introduces basic automatic control. A thermostat manages the temperature setpoint, a time schedule starts heating and ventilation. However, there is no individual zone control and no consumption tracking by end use. This is the most common level in the existing commercial building stock. The BMS works, but it cannot tell the needs of a meeting room from those of an empty office.
Class B BMS: advanced control and zone management
Class B adds zone management and occupancy-based control. Presence detection, scheduling by room or by zone, coordination of HVAC sequences: the building adapts its response to occupants' needs. This level is often targeted for BACS compliance. Comfort improves because control targets each zone instead of applying a uniform setpoint to the whole floor.
Class A BMS: optimized control and consumption tracking
Class A is the highest level. Control is optimized: adaptive setpoints, full HVAC coordination, consumption tracking by end use (thermal, electrical, DHW). Monitoring makes it possible to detect drifts and produce a usable energy report. A BMS in class A can measure what it controls. Energy performance becomes traceable. One decisive nuance remains: class A describes a potential, not a guarantee of energy savings. Without active maintenance of sequences and data, that potential degrades.
Differences between BMS classes and the associated energy savings
Heating, ventilation and air conditioning control
The HVAC scope accounts for most of the gaps between BMS classes. Here is what each level covers, across BMS protocols, in heating, ventilation and air conditioning:
| Function | Class D | Class C | Class B | Class A |
|---|---|---|---|---|
| Setpoint control | None | Fixed thermostat | By zone, adapted to occupancy | Adaptive, predictive |
| Occupancy management | Manual | Building-wide time schedule | Presence detection by zone | Presence + anticipation |
| HVAC coordination | None | Partial | Coordinated sequences | Full coordination |
| Drift detection | None | None | Basic alarms | Automatic analysis |
Lighting and domestic hot water production
Lighting follows the same class logic: manual switching in D, time scheduling in C, dimming based on daylight and presence in B and A. Domestic hot water production is often left out of comparisons. The standard does include it: a class A BMS optimizes DHW heating periods and detects overconsumption caused by poorly balanced recirculation loops. Heat distribution to the various draw-off points can then be adjusted to actual usage periods.
Consumption tracking and energy reporting
The decisive difference between B and A lies in consumption tracking by end use. Class A requires continuous monitoring: thermal, electrical and DHW consumption, broken down by zone or by equipment. This energy report makes it possible to spot a drift as soon as it appears. Without this data, proving a saving is impossible. A building without tracking by end use cannot claim energy performance: it consumes, but it does not know how much or where. This tracking is also what determines what the class can guarantee under an energy performance contract (EPC): without metering by end use, no performance commitment can be verified.
The standard's factors: -30% thermal and -13% electrical in class A compared with class C
BMS classes: the figures that change the picture
Sources: EN 15232-1 standard, Directive (EU) 2018/844, Decree No. 2023-259 on BACS, ADEME 2024
NF EN ISO 52120-1 provides energy impact factors by building type, expressed relative to class C (reference 1.00). For offices, class A corresponds to a factor of 0.70 on thermal energy and 0.87 on electrical energy, i.e. -30% thermal and -13% electrical compared with a class C installation, under standard conditions; class D, conversely, is penalized (factors 1.51 and 1.10), which widens the gap between D and A even further. These energy savings are used to size the potential of a BMS capable of reducing the overall bill, not to predict the energy savings on a given site.
What is the real class of your BMS? A field diagnostic grid
Tick each function that actually works in your building
Your building's class is the class of its weakest function.
| Function | What the standard requires | What often happens | OK? |
|---|---|---|---|
| Setpoint control | Setpoints adapted by zone (class B+) | Single setpoint frozen all year round | |
| Open-window detection | Heating stops when a window opens (class B+) | Contacts never wired or disconnected | |
| Occupancy management | Control based on actual presence (class B+) | AHU running 24/7, nights included | |
| HVAC sequence coordination | Sequences coordinated between systems (class B+) | Permanent manual overrides across several zones | |
| Consumption tracking by end use | Thermal, electrical and DHW metering broken down (class A) | Disconnected meters, data gaps | |
| Drift detection | Automatic analysis of deviations (class A) | No alert configured or read | |
| Energy reporting | Usable reports by end use and by zone (class A) | No report, or report never read |
Setpoint control and open-window detection
The standard requires automatically controlled temperature setpoints from class B upward, and heating shutdown on open-window detection. In the field: setpoints stay frozen at a single value all year round. Window contacts are disconnected or were never wired. Overrides (manual overrides) pile up without anyone removing them. The initial implementation was compliant. Twelve months later, the theoretical class B BMS no longer controls anything.
Occupancy-based control and HVAC sequences
The class B standard requires occupancy-based control. In the field: AHUs run in the middle of the night, permanent manual overrides overwrite time schedules and HVAC sequences have not been coordinated since handover. Occupant comfort suffers as much as the bill. HVAC cooling that runs continuously with no link to occupant presence is a symptom of a degraded BMS. A well-kept operating guide significantly reduces this risk of drift.
Meters and consumption tracking: what the standard requires vs what actually works
Class A requires consumption tracking by end use. What we observe: meters disconnected for months, data gaps over entire periods, double counting between sub-meters and the main meter. Result: no usable baseline to measure energy savings. Without reliable data, the periodic inspection required by the BACS decree only serves to record the gap between the specification and reality.
The class you can reach also depends on the generation of your controllers: Xenta at Schneider, IQ3 at Trend, Niagara AX at Tridium.
How do you assess the real class of an existing BMS?
BMS classes: what level of control for your building?
Explore each class and its concrete impact on energy performance
The EN 15232 standard defines four BMS classes (A, B, C, D) according to the level of automation. Click a class to see its functions, savings and use cases.
Class A is the most advanced level: automatic control with real-time optimization, predictive management and granular consumption tracking.
HVAC setpoints adjust automatically by zone according to actual occupancy and the weather forecast. Optimal start is calculated to reach comfort just as occupants arrive, with no waste.
All technical systems are controlled from a single supervision platform. The interlock between heating and cooling is handled automatically. Time schedules are optimized globally.
Sub-metering by end use (heating, cooling, ventilation, DHW) identifies drifts in real time. Automatic alerts flag any deviation from the reference curves.
Algorithms use the consumption history and the weather to anticipate needs. Optimized optimal start can cut peak demand by 15 to 25% depending on the building's thermal inertia.
Metering data feeds directly into OPERAT declarations (OPERAT is the French government platform where consumption is reported under the Décret tertiaire). The IPMVP methodology demonstrates actual savings adjusted for usage and climate conditions.
Class A is targeted by buildings subject to the Décret tertiaire (France's tertiary decree on energy savings in commercial buildings) that aim to meet their reduction targets (-40% in 2030) without major works.
Class B includes advanced automatic control functions with centralized management, but without the predictive optimization of class A.
Each zone has its own control loop. Setpoints are scheduled by time slot, with automatic switch to setback outside occupancy.
Time schedules automatically handle comfort start-up, night setback and unoccupied periods (weekends, vacations). Changes are made centrally, in one place.
The system prevents heating and air conditioning from running at the same time in a zone. This interlock avoids the waste that is common in poorly tuned buildings.
Faults (failed sensor, stuck valve, temperature drift) are reported automatically. Maintenance response time is considerably reduced as a result.
Metering covers the main end uses (heating, cooling, lighting) with no breakdown by zone. Enough for annual tracking, less suited to continuous optimization.
Class B is the level most often targeted by commercial buildings subject to the BACS decree (HVAC output above 290 kW since 1 January 2025, 70 kW by 2030 at the latest): the decree does not impose any class and class C is deemed compliant, but class B is required for the CEE BAT-TH-116 incentive.
Class C corresponds to basic control: room thermostats, simple timer, no centralized supervision. It is the most common level in the French commercial building stock.
Each zone has a simple thermostat. Control is on/off or basic proportional, with no communication with a central system.
A mechanical or digital timer handles start/stop. No central calendar: each piece of equipment has its own timer, often poorly synchronized.
Faults are only detected after occupant complaints or during a maintenance visit. Response time can reach several days, even weeks.
No sub-metering: the annual bill is the only reference point. Impossible to identify which end use is drifting or which equipment is consuming abnormally.
The BACS decree requires buildings in scope to provide specific functions (hourly tracking by zone, drift detection, interoperability, manual shutdown - Article R. 175-3 of the French Construction and Housing Code, CCH) from 2025 (output > 290 kW) or by 2030 at the latest (> 70 kW). A class C within the meaning of the standard is deemed compliant (ministry guidance, January 2026), but basic control without hourly consumption tracking generally does not reach it.
Most of the French commercial building stock is still in class C. Moving to class B is not a regulatory obligation, but it is the level required for the CEE BAT-TH-116 incentive and the one that secures coverage of the decree's functions.
Class D refers to a building without any automation: manual adjustments, no scheduling, no tracking. This is the case for older buildings that were never equipped.
Valves, dampers and switches are operated manually. No thermostat, no sensor. Comfort depends entirely on human intervention.
Equipment runs continuously (nights, weekends, vacations). Heating can stay on with windows open, with no detection or cut-off.
Without metering or data reporting, failures and maladjustments go unnoticed. A piece of equipment can run idle for months without anyone noticing.
Without control, temperature differences between zones are significant. Occupant complaints increase, affecting productivity and tenant satisfaction.
A class D building must climb at least one level (class C, deemed compliant) and ideally two (class B, eligible for CEE) for BACS compliance. The upgrade involves installing sensors, controllers and connected supervision.
A class D building overconsumes by 30 to 50% on average compared with an equivalent class A building. The cost of inaction quickly exceeds the cost of the upgrade.
Sources: EN 15232-1:2017 standard, BACS decree 2020, ADEME 2024, EN 15232 impact factors for offices
The actual class of your BMS installation is determined by its weakest function. Four questions are enough to place a BMS within the classification:
- Are your temperature setpoints automatically controlled by zone?
- Do your HVAC sequences adapt to building occupancy?
- Do your meters report usable data without interruption?
- Does your supervision detect drifts and generate an energy report?
A single "no" is enough to downgrade the whole system. The BMS class written into the specification only counts if every function is working.
BACS compliance, standard classification and CEE eligibility: three logics not to confuse
Click each block to see the details
BACS decree
Decree No. 2020-887
Sets functional requirements (Art. R. 175-3 CCH): hourly consumption tracking by zone with adjustment of systems, drift detection, interoperability, manual shutdown. Does not formally refer to a class of the standard; a class C is deemed compliant (ministry guidance, January 2026).
Legal obligationNF EN ISO 52120-1 standard
International technical reference
Classifies automation functions into 4 levels (A, B, C, D). Serves as a common reading grid. Has no regulatory force in itself.
Technical classificationCEE sheet BAT-TH-116
CEE energy-savings certificates
Gives entitlement to the CEE incentive for class A or B BMS only. BACS-compliant does not mean CEE-eligible.
FundingThese three frameworks are complementary - they are not interchangeable.
What the BACS decree actually requires (and what it does not impose)
The BACS decree (Decree No. 2020-887) sets functional requirements for commercial buildings (Article R. 175-3 of the French Construction and Housing Code, CCH): continuous monitoring, logging and analysis of consumption by functional zone at an hourly time step with adjustment of systems, detection of efficiency losses, interoperability and the possibility of manual shutdown. The text does not explicitly refer to a class of NF EN ISO 52120-1, and the ministry's application guide (January 2026) states that a class C is deemed to meet the requirements. The dominant market reading remains "class B minimum". The decree imposes. It does not recommend. The regulation targets an operational result in the commercial sector: control setpoints and measure consumption.
What the NF EN ISO 52120-1 standard classifies (A, B, C, D)
NF EN ISO 52120-1 is a technical reference. It classifies building automation and control functions into four levels (A, B, C, D) according to their degree of automation. This standard classification serves as a common reading grid. It has no regulatory force in itself. The decree draws on it to describe its requirements, but the standard and the legal obligation remain two separate logics.
Which class for CEE sheet BAT-TH-116?
Sheet BAT-TH-116 requires a class A or B BMS within the meaning of the ISO 52120 standard to give entitlement to CEE energy-savings certificates. The CEE scheme only covers these two levels. A building that complies with the BACS decree is not automatically eligible for the CEE sheet. Conversely, an eligible system does not exempt the building from regulatory compliance. CEE funding and the BACS obligation follow two separate logics, one of funding, the other of compliance. To receive the financial support, the manager must put together a file that certifies the class of the system.
Up-to-date BACS deadlines: pushed back to 1 January 2030 for 70-290 kW
The BACS decree sets three compliance thresholds based on the rated output of the HVAC system:
- Buildings > 290 kW: compliant since 1 January 2025
- Buildings 70-290 kW: deadline pushed back to 1 January 2030 by Decree No. 2025-1343 of 26 December 2025
- New buildings: not affected by the postponement
The postponement changes nothing about the obligation. It shifts the timetable for intermediate outputs. The time gained is an advantage for companies that have not yet started their compliance project. Upgrade works still need to be planned now.
Why does keeping the class require continuous operational follow-up?
The distinction between potential and achieved sums it all up. A class is not decreed: it is maintained through active supervision of sequences, removal of manual overrides and regular checking of metering data. Installing a BMS is only the first milestone. Without day-to-day optimization, drift returns. Operational follow-up is the only safeguard between the class written into the contract and the one the building actually lives with. This rigor reduces operating costs measurably over time.
How does Foobot make your buildings' BMS reliable and optimize it?
BMS advisory: diagnose the actual class and put the BMS back in order
Our BMS advisory starts by diagnosing the actual class of an existing BMS installation. We identify active manual overrides, overwritten HVAC sequences and silent meters. Our engineers' advice covers each function to bring back to the level set in the specification, without major works or hardware replacement. Making the meters reliable restores usable tracking. The building gets back a reliable foundation before any optimization. The company can thus make use of a sensor network already in place, remotely, with no additional deployment.
AI Control: going beyond class A with predictive control
When the BMS is reliable and the building has real complexity, our AI Control takes over. A custom digital twin is trained on the building's history, the weather and occupancy. Predictive control adjusts setpoints every 15 minutes, 24/7, taking thermal inertia and solar gain into account. The benefit: energy efficiency beyond what a class A BMS can achieve on its own, with measurable energy savings. This system controls the distribution of heating and cooling to each zone of the network.
Savings measured under the IPMVP protocol: the Valeo example (-28.6% HVAC consumption)
Valeo: moving to BMS class A on a 22,000 m² commercial site
Smart control without replacing existing HVAC equipment
Valeo commercial site (offices + R&D) of 22,000 m² in the Paris region. Existing BACnet supervision, original HVAC equipment (2012). Objective: reach BMS class A (EN 15232) and reduce energy consumption without installation works.
Full mapping of the 1,840 existing BACnet points on site. Identification of the control functions in place (basic time sequences, fixed setpoints) and of the gaps against class A requirements.
Finding: the site was operating in class C, with unadjusted time slots and no adaptive control on HVAC terminal units.
Connection to the existing supervision and deployment of the control algorithms:
• Adaptive terminal unit control of fan coil units and AHUs by zone, based on actual occupancy
• Optimization of optimal start sequences (pre-heating, pre-cooling) based on the building's thermal inertia and the weather forecast
• Intermittent operation management: automatic setback when unoccupied, early shutdown at the end of the day
Implementation of a measurement and verification plan compliant with the IPMVP protocol (option C) to quantify actual savings, adjusted for weather and occupancy variations.
Fine-tuning of optimal start parameters and heating/cooling changeover thresholds after a first full seasonal cycle.
Validation of compliance with the class A criteria of the EN 15232 standard:
• Individual terminal unit control with presence detection and inter-system communication
• Optimized management of generation (sequencing, heating curve adaptation)
• Continuous energy tracking with automatic drift detection
• Automated reporting for the Décret tertiaire (OPERAT platform)
Continuous control with automatic seasonal adjustment. Real-time alerts on consumption drifts and control faults (stuck valve, offset sensor).
Quarterly performance review with the site's technical manager to decide on further optimizations.
Request a BMS diagnostic for your site
Sources: data representative of a BMS control project in a commercial building, IPMVP protocol option C, EN 15232-1:2017 standard
At Valeo, we measured -28.6% HVAC consumption under the IPMVP protocol, with weather correction based on heating degree days (HDD). This method makes the energy savings auditable by an independent third party. No declared savings. A verifiable measurement. The key information for the manager: this result was obtained on an industrial-tertiary site whose gas network supplied heat production, without replacing existing equipment.
Choosing the right BMS class for your commercial portfolio
Too many managers aim straight for class A when their portfolio does not have the technical prerequisites. In 80% of cases, moving from class C to class B is enough to capture most of the energy savings, for a far more reasonable investment. The real question is not "which is the best class?" but "what is the best ratio between energy savings and available budget for my building?".
Before setting a target, carry out an assessment against EN ISO 52120-1. Many commercial buildings are in class C or D without the manager knowing it. Identify the control functions already in place (time scheduling, presence detection, terminal unit control) to measure the real gap with the target class.
Moving from class C to class B adds advanced optimization functions (demand-based control, inter-system management). This is generally where the payback is shortest, often between 2 and 4 years. Class A requires predictive management and continuous optimization loops, which assumes a more mature data infrastructure.
Under the BACS decree (2020, strengthened in 2023, 70-290 kW deadline pushed back to 2030 in 2025), non-residential commercial buildings whose heating or air conditioning exceeds 290 kW (since 2025, then 70 kW by 2030 at the latest) must have a BACS providing the functions of Article R. 175-3 CCH. No class is imposed: a class C is deemed compliant, and class B gives entitlement to CEE. The decree does not provide for a specific financial penalty, but the periodic inspection records the gaps. That is one more argument for planning the class upgrade now.
Moving up a BMS class does not necessarily mean replacing equipment. A software control layer connected to the existing BMS (BACnet, Modbus, LonWorks) can activate class B or A functions without HVAC works. It is the fastest strategy to roll out across a multi-site portfolio.
Changing BMS class without measuring actual savings is flying blind. Require verification under the IPMVP protocol (International Performance Measurement and Verification Protocol). It is the only way to prove that the class upgrade produces real savings, adjusted for weather and occupancy variations.
Ref.: EN ISO 52120-1 standard, BACS decree No. 2020-887
The 5 milestones to reach BMS class A
Click each step to see the operational details
The EN ISO 52120-1 standard defines four BMS classes (D, C, B, A). Taking an existing BMS from class C or B to class A requires a structured path. Here are the concrete milestones.
A commercial building controlled in class A under EN ISO 52120-1 can reach a BMS efficiency factor of 0.70 on thermal energy and 0.87 on electrical energy (offices), i.e. a consumption reduction of 13 to 30% compared with a class C BMS (reference 1.00).
Sources: EN ISO 52120-1:2022, BACS directive (EU) 2018/844, ADEME 2024, feedback from commercial building projects in France
FAQ - BMS classes
Which buildings can be fitted with a building management system?
Any commercial building can be fitted with a building management system: offices, hospitals, nursing homes, shopping centers or industrial-tertiary sites. Multi-unit residential buildings are technically compatible but rarely equipped. Relevance depends on building size and the complexity of the HVAC equipment to be controlled.
What are the application areas of a building management system?
A building management system covers heating, ventilation and air conditioning (HVAC), lighting, domestic hot water production, fire safety and access control. Each area can be automated and supervised independently or in a coordinated way, depending on the class of the system.
What does GTB mean?
GTB stands for "gestion technique du bâtiment", the French term for a building management system (BMS). This system brings together the controllers, sensors and software that supervise and control a building's technical equipment: heating, ventilation, air conditioning, lighting. The BMS centralizes commands and operating data on a supervision dashboard.
What is the purpose of a BMS?
The main purpose of a BMS is to improve energy efficiency while maintaining occupant comfort. It enables centralized control of HVAC and lighting equipment, detection of consumption drifts and automatic adaptation of setpoints to occupancy conditions.
Who installs the BMS?
A BMS is installed by an integrator specializing in building electronics. This contractor installs the controllers, sensors and supervision software. It programs the control sequences and connects the HVAC equipment. The position of the BMS in the technical chain justifies independent BMS advisory to check compliance.
What is a BMS functional analysis?
A BMS functional analysis describes the expected behavior of each controlled system: control sequences, alarm thresholds, interactions between functions. This document translates the building owner's needs into technical specifications for the integrator. Without a rigorous functional analysis, the BMS may fail to meet the requirements of the targeted BMS class.
What is the difference between a class A BMS and a class B BMS?
A class A BMS includes consumption tracking by end use and monitoring of energy drifts. Class B handles zone control and adaptation to occupancy, without that level of reporting. Class A adds measurable proof of performance.
Which standards and subsidies apply to the different BMS classes?
The NF EN ISO 52120-1 standard defines the BMS classes (A, B, C, D). CEE sheet BAT-TH-116 gives entitlement to the CEE incentive for class A or B systems only. The BACS decree sets the regulatory obligations. These three frameworks are complementary but distinct.