Décret tertiaire: absolute or relative reduction target?

Quick answer. France's tertiary decree lets owners choose between two reduction paths. The relative target (Crelat) requires cutting consumption by 40 % by 2030, 50 % by 2040 and 60 % by 2050 against a reference year. The absolute target (Cabs) sets a fixed consumption ceiling in kWh/m²/year per activity. Choosing between an absolute or relative décret tertiaire target, and setting the right reference year, radically changes the effort required.

Facing a tertiary property portfolio, the first question is not technical but strategic: which path to commit to. The Éco Énergie Tertiaire scheme, stemming from the ELAN law and decree no. 2019-771 of 23 July 2019, offers two routes to the same 2030, 2040 and 2050 milestones. Many owners and operators report their data on the OPERAT platform without having settled this method choice, even though it drives the scale of works and the budget. This article explains the difference between absolute and relative targets, how the reference year shapes the result, and where an accountant adds value on costing.

The scheme applies to any building, part of a building or group of buildings hosting tertiary activities over an area of at least 1,000 m². The framework rests on article L174-1 of the Construction and Housing Code, decree no. 2019-771 of 23 July 2019, and the so-called method order of 10 April 2020, completed by successive absolute-value orders.

The obligation is twofold. First, report each year, before 30 September, the previous year's consumption on the OPERAT platform run by ADEME. Second, meet a path of final energy reduction at the three decade milestones: 2030, 2040 and 2050. The decree leaves a choice on how to express that path.

The relative target (Crelat)#

The relative method consists of reducing consumption against a reference year specific to the building. The objectives are progressive: 40 % reduction by 2030, 50 % by 2040 and 60 % by 2050, against that reference year's level.

The reference year is a period of 12 consecutive months, chosen between 2010 and 2019, or the first full year of operation for a more recent building. This is the sensitive point: the higher the consumption of the year chosen, the wider the absolute target to reach, hence the easier it is to meet.

The absolute target (Cabs)#

The absolute method sets, for each activity category, a maximum consumption ceiling expressed in kWh/m²/year, independent of the building's history. This Cabs ceiling adds a component tied to building uses (heating, cooling, ventilation, hot water, lighting) and a component tied to the trade's specific uses. The values are published by order and adjusted for climate zone and altitude.

This method suits recent or already efficient buildings, for which a 40 % cut from an already low consumption would be technically very costly, or even impossible.

Under the relative target, the reference year is not neutral. A building that picks a low-consumption year imposes a very low target on itself, sometimes out of reach. Conversely, keeping a truly representative year, or even the historically most energy-intensive year within the allowed window, mechanically lowers the remaining effort. This work means reconstructing consumption that is sometimes old, over 12 consecutive months, which is not always easy when the 2010 to 2019 bills are no longer archived.

Switching between the two methods stays possible from one OPERAT report to the next. In practice, many managers start with the relative target, then check whether the absolute target would be more reachable once the first works are done.

In the files we support, the most frequent mistake is not the method choice itself, but postponing it. As long as the path is not settled, no works plan or budget can really be framed. Yet milestones cannot be caught up: a delay taken towards 2030 is paid for through concentrated, more costly investment afterwards.

Our conviction is that this choice should be treated as a management decision, not a reporting formality. The right method is the one that, for a given building, makes the path credible in view of its nature, its use and the investment capacity of the owner or operator.

The decree provides for modulations that ease the objective. They relate to technical or heritage constraints (risk to the structure, protected building), to a change in activity volume (calculated automatically by OPERAT via intensity indicators), or to manifestly disproportionate costs. On this last point, the payback period is the deciding test: an action is deemed disproportionate beyond 30 years for envelope works, 15 years for equipment, and 10 years for control and regulation systems.

A modulation request must be declared in OPERAT, at the latest within 5 years after the first reporting milestone of a decade, with a supporting technical file. This aspect is often neglected, even though it can reconcile a theoretical objective with the economic reality of a portfolio.

An accounting firm is not a thermal engineering office. The energy audit, the choice of works and the ceiling calculation belong to a specialist. The accountant works on its own ground:

• Multi-year costing: budgeting works by milestone and smoothing their cash-flow impact.
• Financing plan: combining self-funding, borrowing, energy savings certificates and available grants.
• Accounting treatment: distinguishing expenses from fixed assets, tracking depreciation of works.
• Consistency with reporting: linking the energy path to the sustainability information the company already produces.

This is the angle of our support in CSR and CSRD sustainability reporting, often combined with outsourced CFO support when investment weighs on cash flow. For the overall calendar and sanctions, see our article on OPERAT obligations and tertiary decree milestones.

A company owns a 2,400 m² office building occupied since 2008. Its manager considers the absolute target out of a reflex for simplicity. By reconstructing consumption, we find that 2012, particularly energy-intensive before the boiler was replaced, is an eligible reference year. Under the relative target, the 40 % objective by 2030 calculated on 2012 turns out more reachable than the absolute ceiling, because the 50 % cut already achieved since 2012 covers much of the path. The works plan is then refocused on ventilation and controls, with a payback under 10 years, rather than on a heavy envelope renovation.

• Annual reporting: the previous year's consumption must be entered in OPERAT before 30 September, every year.
• Reversible choice: the method can change from one report to the next; nothing forces freezing the absolute or relative target from the first year.
• Sanctions: failure to report or to follow a path exposes the owner to a formal notice, then an administrative fine of up to 7,500 € for a legal entity, with publication of the breach.
• Reference year: keep and secure consumption evidence from the 2010 to 2019 period, or risk defaulting to the absolute target.