Smart & Connective

Existing tertiary buildings: How to save energy?

With 43% of France's annual energy consumption ( source OID ), existing tertiary buildings play a major role in overall energy consumption. Their energy efficiency has become a major concern as we seek to reduce our carbon footprint and preserve the ecosystems present on the planet. Rising energy costs have also pushed the tertiary sector to review their approach to energy consumption.

The construction of new tertiary buildings takes into account climate issues. But we cannot ignore the environmental impact of already existing buildings. This is why this article explores the strategies and solutions that make it possible to transform these tertiary buildings into a model of energy efficiency, while reducing costs for operators.

Understanding the challenges of energy efficiency in existing tertiary buildings

Energy renovation of existing tertiary buildings

Very often, existing tertiary buildings face energy inefficiency problems due to their age and outdated systems. Energy renovation therefore consists of implementing measures to improve their energy performance while reducing energy consumption.

Among these measures, we can cite insulation, the replacement of outdated systems such as air conditioning, ventilation or heating (HVAC), the installation of energy-efficient lighting, or even the installation of Technical Building Management (BMS) in order to intelligently optimize the equipment and systems of the said building.

The benefits of energy savings in existing tertiary buildings

Unsurprisingly, improving the energy efficiency of a tertiary building not only saves energy but also reduces energy bills. This element appears to be crucial in an economic situation where energy prices continue to increase. INSEE also estimates an increase in electricity costs of 77%* for the tertiary sector in 2023.

* These forecasts do not take into account government measures such as the “electricity shock absorber”, the “gas and electricity bill payment assistance window”, the “capping for VSEs” and possible price discounts. the part of suppliers.

Likewise, tackling the energy problem in the existing tertiary sector is a way of responding to the climate challenges we face. We know that we must significantly reduce greenhouse gas (GHG) emissions. We must also preserve as many resources as possible if we want to fight global warming. Thanks to the development of energy efficiency in existing tertiary buildings, we contribute to sobriety and the reduction of the carbon footprint.

We can thus preserve resources such as energy. But also limit the depletion of natural resources such as sand, essential in the construction sector.

Reminder: BACS and Tertiary decrees

To respond to the climate emergency, the French government has implemented the tertiary decree (DEET). The latter aims to frame the implementation of actions aimed at considerably reducing the energy consumption of tertiary buildings. These include those of more than 1000 m² (or combined surface area if the activity is present on several sites).

Achieving these objectives can only be encouraged with the implementation of the BACS (Building Automation & Control Systems) decree. It requires tertiary buildings with an air conditioning or heating system with a nominal power greater than 290 kW to be equipped with an automation and control system (a GTB) by January 1 , 2025.

NB: This decree has already been revised since for January 2027, this threshold is lowered to 70 kW.

Energy audit and needs assessment

Why is an energy audit essential?

The energy audit is the starting point for any approach aimed at improving the energy efficiency of an existing tertiary building. The principle is simple: evaluate in detail (item by item) the current energy consumption of the building.

Energy audit (1)

This step is essential since it allows,

  • Identifying problems : The audit helps detect areas of energy waste and failing systems. This allows you to have a clear overview of the necessary improvements.
  • Establishing priorities : The audit helps prioritize energy renovation actions. It is indeed necessary to be able to establish a classification of measures according to constraints (temporal, financial, technical, etc.).
  • The basis of planning : The audit provides all the elements necessary for implementing actions in favor of energy efficiency.

To go further, European legislation requires, every 4 years, an energy audit in the tertiary sector for companies with more than 250 employees or with a turnover greater than €50 million or a balance sheet total greater than €43 million. '€. In France, the tertiary energy audit benchmark is also represented by the NF16247 standard.

NB: Companies certified ISO 50001 – Energy management are exempt.

How to achieve it?

Carrying out an energy audit requires the intervention of a qualified professional such as an Energy Manager. To optimize your work, you must first collect all the data on the energy consumption of the building(s).

The energy audit can then be carried out by the Energy Manager using the following steps :

  • Data analysis ;
  • On-site inspection;
  • Identification of energy efficiency measures;
  • Evaluation of profitability;
  • Audit report ;
  • Implementation of measures;
  • Continuous monitoring and evaluation.

GTB Light: Lever to maximize energy savings in existing tertiary buildings

ADEME estimates that 70% of installed GTBs are poorly or even not used due to their complexity. To respond to the problems of classic GTBs and simplify energy savings in existing tertiary buildings, Light GTBs based on IoT technology have been created.

The advantages of the GTB Light

  • Compatible with existing buildings : GTB Light can be installed in existing tertiary buildings (offices, retail, public buildings, hotels, etc.) but also in existing systems.
  • No work required : IoT technology allows the automation of energy-intensive devices without the need to carry out work in the building.
  • Quick and simplified installation : Thanks to its architecture (hardware and software), the GTB Light can be deployed quickly and easily on site.
  • Accessible handling : The user interface guarantees control and simplified data management.

The GTB Light Smart & Connective goes further

Multisite, without work, turnkey, interoperable… the advantages of GTB Light Smart & Connective are numerous!

To further maximize energy savings in existing tertiary buildings , Smart & Connective simplifies operations thanks to its simple and quick to install GTB Light.

By being installed at room level and at building level, it allows the realization of even more efficient energy saving scenarios. For example, relying on real-time data such as presence, air quality or the opening of windows in a room.

In addition, thanks to its multisite interface, it is possible to monitor data remotely. The GTB Light Smart & Connective thus makes it possible to respond to the energy challenges of existing tertiary buildings.


Given the context, this is no longer a surprise; it is now essential to tackle the problem of energy savings. And existing tertiary buildings have a role to play.

Carrying out an energy audit allows them to identify energy efficiency needs. To respond to this, BMS Light, such as that of Smart & Connective, can be identified as one of the main levers contributing to energy performance.

In fact, they allow existing tertiary buildings to:

  • Control energy costs.
  • Save energy.
  • Limit their carbon footprint and strengthen their CSR commitments.
  • Comply with regulations.
  • Improve their energy efficiency.

“The best energy is that which we do not consume. »