France’s BACS decree: building automation requirements

The French décret BACS sets a functional standard for automation and control in much of the non-residential building stock. BACS is the English abbreviation used in the French rules. In French project documents the same system is usually called a système d’automatisation et de contrôle des bâtiments or a système de gestion technique du bâtiment (GTB).

The rule is about the complete building system. Installing a meter, an IoT sensor or an energy dashboard does not by itself satisfy it. The system must collect and analyse energy data, adjust the connected technical systems, identify losses in efficiency and allow both autonomous management and manual intervention.

Which buildings are in scope

Article R. 175-2 applies to buildings used for commercial or non-commercial tertiary activities, including tertiary buildings owned by organisations in the primary or secondary sectors. The trigger is a heating or air-conditioning system, with or without ventilation, whose useful rated output is above 70 kW.

The owner of the heating or cooling system carries the obligation. Where heat or cooling comes from a district network through a heat exchanger, the relevant output is the exchange station’s output.

This produces a different scope from the separate Eco Energie Tertiaire scheme. A 700 m² building can be in BACS scope when its heating system is above 70 kW. A 1,500 m² building can be in Eco Energie Tertiaire scope even when no individual heating or cooling system crosses the BACS threshold.

France's room or zone temperature-control and pipe-insulation duties use different building and system tests. A building can fall under either of those duties without being required to install a BACS.

Deadlines in the current code

The 70 kW deadline for existing buildings was originally 1 January 2027. Decree 2025-1343 changed it to 1 January 2030. A project brief that still states 2027 is out of date, although replacement of the heating or cooling system can create an earlier trigger.

The code provides an exemption where the owner establishes that the installation cannot achieve a simple payback of less than ten years. For an existing building, public financial assistance is deducted in the calculation and the connectable technical systems are assessed on the same payback basis. Treat that as a documented project decision, not as a reason to omit measurement from the feasibility study.

What the BACS must do

Article R. 175-3 defines four functional requirements.

1. Monitor, record and analyse energy continuously. Data for the connected building systems is organised by functional zone at an hourly interval. The system adjusts the technical systems in response. Monthly data is retained for five years.
2. Benchmark performance and detect losses. The system compares energy efficiency with values from energy studies or the characteristics of each technical system, detects a fall in efficiency and informs the operator about possible improvements.
3. Interoperate with the building systems. Existing plant cannot remain a collection of isolated dashboards if the required system is expected to act on it.
4. Allow manual stop and autonomous management. The operator retains a manual path, while the system can manage one or more technical systems automatically.

The owner owns the data produced and archived by the system. The owner must make it available to the building manager on request and give each technical-system operator the data concerning that operator’s system.

How BACS relates to the tertiary energy rules

Eco Energie Tertiaire applies to covered tertiary buildings, parts of buildings or building groups with at least 1,000 m² of tertiary floor area. It sets two alternative forms of target: a reduction against a reference year, or an absolute consumption level for the activity. The relative targets are 40% by 2030, 50% by 2040 and 60% by 2050. Consumption is reported through ADEME’s OPERAT platform.

BACS supplies an operational way to find and correct waste. OPERAT is the regulatory record of annual consumption and progress. One does not replace the other. A useful project connects them through a common meter register and consistent boundaries:

• fiscal energy totals for the annual OPERAT declaration;
• submetered electricity, gas, heat and cooling for each functional zone;
• plant state, set points, schedules and alarms from the BACS;
• a stable mapping from each meter and zone to the building entity used in reporting.

If the annual total changes but the submetered zones do not reconcile with it, the team cannot tell whether performance improved or the measurement boundary changed. The meter reconciliation guide gives the checks.

A practical retrofit measurement plan

Start with the systems and boundaries before selecting hardware.

A meter list is not yet a BACS design. For every point, name its physical boundary, unit, source protocol, sampling interval, retained history, alarm owner and the system allowed to write to it. Keep safety, equipment protection and legally required controls in the plant controller. A supervisory system should request an operating state through the manufacturer’s documented interface rather than bypassing the controller.

Existing plant and mixed protocols

Older buildings commonly contain several generations of equipment. A BMS may use BACnet/IP, BACnet MS/TP, Modbus TCP and Modbus RTU alongside pulse meters and 4-20 mA transmitters. Inventory the existing interfaces before proposing replacements.

Use read-only integration first. Confirm address, data type, scale, sign and unit against the local display. Then compare a complete operating period with an independent meter. Enable a write only when the manufacturer documents the writable object or register, the plant owner approves the control boundary and a failed command has a defined safe outcome.

The BMS and SCADA meter-integration guide covers the data path. The BACnet object guide and Modbus commissioning guide cover the two common interfaces.

Maintenance, training and inspection

The obligation continues after handover.

• Article R. 175-4 requires periodic checks by a competent internal person or external provider. Written instructions must define the interval, points checked and prompt repair or replacement of failed components.
• Article R. 175-5 requires the owner to ensure that the operator is trained, including how to configure the system.
• Article R. 175-5-1 requires periodic inspection initiated by the owner. The inspection covers the functional analysis on the first visit, correct operation, the Article R. 175-3 functions, configuration against current building use and recommendations.
• The inspector gives the owner a report within one month. The owner keeps it for ten years.

Keep an acceptance record that an inspector can repeat: meter totals against the fiscal supply, sensor values against a reference, alarms created from a known test condition, schedule changes reaching the plant, manual stop, autonomous control, communication loss and recovery, and access to the retained history.

Where EpiSensor fits

EpiSensor provides an operational monitoring and integration layer around existing building plant. Electricity monitors can separate HVAC and plant feeders. Pulse and M-Bus interfaces can collect gas, water and heat-meter totals. Modbus and analogue interfaces can bring existing controller states and process measurements into Edge. A Gateway keeps the record on site and can serve collected data onward over Modbus TCP, MQTT or HTTP.

That can close measurement gaps, give an existing BMS independent energy evidence and connect meters that would otherwise remain isolated. It does not turn every installation into a compliant BACS. The complete project must still meet the Article R. 175-3 functions, connect the systems required by Article R. 175-2, retain the specified records and pass the required inspection.

For a first survey, use the HVAC energy-monitoring guide to map supplies and schedules, then the System Builder to identify the interfaces needed for each measurement point.