Every year, the same file comes back to the technical manager’s desk: the declaration to be filed on the OPERAT platform before the 30 September deadline. Gas consumption comes from a meter, and so does electricity. Lighting, however, has never had a dedicated meter.
Who is covered by the tertiary energy savings scheme
The tertiary energy savings scheme, which stems from the decree of 23 July 2019 issued under the ELAN law, covers buildings, parts of buildings and groups of buildings housing tertiary activities on a floor area of at least 1000 square metres. Areas add up on the same site, which brings into the scheme sites that believed they were outside its scope.
The targets are expressed as a reduction in final energy consumption compared with a reference year: 40 % in 2030, 50 % in 2040 and 60 % in 2050. A second route exists, based on reaching a consumption level in absolute value, set by order according to the category of activity.
What the OPERAT platform expects for lighting
The annual declaration covers consumption by type of energy, the declared floor areas and the intensity-of-use indicators of the functional entity subject to the scheme. The item-by-item detail is not systematically entered line by line.
Lighting data nevertheless becomes essential as soon as the file has to be defended: justifying the reference year, requesting an adjustment of the targets, building the action plan, explaining a difference from one year to the next. A building owner unable to isolate its lighting item deprives itself of the quickest lever to activate in a tertiary building.
Reconstructed data remains acceptable provided it is documented. The rule of conduct fits in three points: write down the method used, keep the documents that support it, and repeat the same method from one year to the next. An item calculated with two different methods over two financial years produces an artificial difference that will then have to be explained.
Reconstructing consumption without dedicated sub-metering
Three methods coexist, from the most reliable to the most approximate. The choice depends on what the electrical panel can measure and on the time available before the deadline.
Method | Data required | Reliability |
|---|---|---|
Dedicated metering | Meter or measuring module fitted on the lighting circuits | High, directly usable |
Extrapolated spot measurement | Reading of the power drawn on the circuits, combined with the real time slots | Good if operating patterns are stable |
Calculation from the inventory | Luminaire base, system power, annual operating hours | Fair if the inventory is complete and documented |
Calculation from the inventory remains the most widely used method. For each family of luminaires, it consists of multiplying the system power by the number of fittings and by the annual hours of use, then correcting the whole for the effects of dimming and presence detection where they exist.
Inventory of the installed base: the foundation of any credible calculation
A usable inventory is not limited to the number of luminaires. For each zone, it needs the technology, the power of the system and not just of the lamp, the number of fittings, the mounting height, the type of control and whether any management system is present.
System power is the point most often distorted. A 58-watt fluorescent tube draws more once its ballast is taken into account, and an LED luminaire consumes the power of its driver, not just that of its modules. Using the rating plate value rather than a catalogue value avoids most of the discrepancies.
This inventory is not wasted work. It is the first document of any on-site lighting audit and it will be used again when the works are costed.
Reference year and the effect of a renovation already carried out
The reference year is chosen among the full years of operation between 2010 and 2019. This choice is binding: it is against this year that the reduction trajectory will be calculated for the whole duration of the scheme.
A site that has already renovated its lighting should choose a year prior to the works, provided it holds the corresponding proof of consumption. Choosing a later year amounts to erasing a saving already achieved and having to find it elsewhere. The mechanisms specific to office floor areas are detailed in our article on the tertiary decree applied to office lighting.
The most frequent declaration errors
- Using the power of the sources rather than the power drawn by the complete system, auxiliaries included.
- Forgetting zones lit permanently: circulation areas, toilets, plant rooms, signs, covered car parks.
- Confusing opening hours with real lighting hours, often longer because of cleaning and maintenance teams.
- Ignoring emergency lighting units in permanent operation.
- Declaring a floor area that does not match the perimeter of the functional entity subject to the scheme.
- Keeping a frozen inventory when zones have been renovated during the year.
Each of these errors is corrected by a field survey carried out zone by zone. None of them is corrected in front of a spreadsheet.
Moving from the declaration to the action plan
Once the lighting item is isolated, it becomes comparable with the other uses and therefore possible to prioritise. It is generally the item where the ratio between investment effort and annual saving is easiest to demonstrate, because the operating hours are known and dimming brings a measurable saving without touching the company’s processes.
The action plan is then built zone by zone, cross-referencing the inventory, the levels actually measured and the requirements that apply to the room. The standards to be met are gathered on our page dedicated to the compliance of lighting installations, and LED luminaires for offices and open-plan spaces cover most of the zones concerned in a tertiary building.
To reconstruct your lighting item before the next declaration deadline, request a site visit from the contact page.
