What is RT global and RT element by element?
Réglementation Thermique (RT) is a French standard designed to improve the energy efficiency of new and renovated buildings. It sets specific requirements for :
Opaque walls (walls, roofs, floors)
Glass walls
Heating
Domestic hot water
Cooling
Ventilation
Lighting
New Renewable Energies (NRE)
The existing RT refers to the rules applicable to old buildings during renovation, extension or conversion work. Its main aim is to improve the energy efficiency of existing buildings by reducing energy consumption.
The RT existant globale evaluates the energy consumption of the building as a whole, while the RT existant élément par élément analyzes each component separately.
Regulatory texts
The existing RT is defined by a series of regulations, notably the decree of May 3, 2007 and June 13, 2008.
Bond applications
These obligations apply to two main types of building:
Buildings of less than 1000 m², regardless of the level of thermal work undertaken.
Buildings over 1,000 m² with light renovation work.
These regulations also apply to residential buildings, and seek to improve thermal resistance while complying with building permits issued since May 2007.
Understanding the existing RT: what is the difference between the overall existing RT and the RT element by element?
The RT globale and RT élément par élément are two methods of calculating the energy performance of buildings.
The global RT takes into account all the elements that influence energy consumption, imposing a maximum primary energy consumption for the whole building and a certain quality of thermal and acoustic comfort.
RT element by element,
on the other hand, involves assessing the energy performance of each building component separately. This method makes it easier to identify the building's weak points, and to determine the improvements that need to be made to each component to optimize its energy performance.
The RT globale applies to major renovations to buildings that meet the following criteria:
Net floor area (SHON) greater than 1000 square meters.
Cost of thermal renovation work decided by the project owner exceeds 25% of the building's value excluding land.
Date of completion after January 1ᵉʳ, 1948.
How to choose between global RT and element-by-element RT?
The choice between RT global or RT element by element depends mainly on the context and objectives of the construction or renovation project. The RT existant globale is a calculation method that is simpler and quicker to implement than the RT existant élément par élément. It is therefore frequently used for new buildings or renovation projects that do not require major work on the building envelope.
On the other hand, element-by-element RT offers a more precise calculation approach and is better suited to targeted energy renovation projects. It identifies weak points in the building envelope and determines the improvements needed to optimize its energy performance. This method is particularly recommended for heavy renovation projects where significant interventions on the building envelope are essential to achieve energy performance targets.
It is important to consider thecosts associated with each calculation method. Existing RT element-by-element is often more costly, as it requires expertise and detailed analysis of each building component. However, this approach can lead to substantial energy savings over the long term, offsetting the increased initial outlay.
Since March 22, 2017, homeowners have been obliged to incorporate thermal insulation work into their renovation projects, even for those of a purely aesthetic nature. This work, often carried out on facades and roofs, aims to combat "thermal flaws" by improving the thermal resistance of buildings to reduce their environmental footprint.
How can Trimble help you achieve your RT objectives, whether global or component by component?
Trimble provides effective tools to help professionals comply with these regulations, whether it's for the overall RT existant or the RT existant element by element. Trimble Nova software enables detailed thermal simulations of the existing building envelope, providing a detailed assessment of its current energy performance. This analysis can be used to identify the work required to meet RT requirements, either overall or component by component.
Thermal simulations and energy savings
Thermal simulations carried out using Trimble Nova help to predict the potential energy savings resulting from renovation work. These detailed analyses also reveal the impact of improvements on occupants' thermal comfort, enabling precise and efficient planning.
Designing optimized HVAC systems
For existing buildings, Trimble helps professionals design more efficient, energy-saving heating, ventilation and air conditioning (HVAC) systems. Using detailed 3D models of existing buildings, the software can simulate the building's thermal performance and identify the best technical solutions for complying with the overall RT existing and the RT existing element by element.
Collaboration between stakeholders
With a common 3D model, all stakeholders can work together to optimize the design of renovation work. This guarantees technical consistency in the solutions implemented, maximizing the efficiency of renovations in line with the requirements of the RT existant global or RT existant element by element.
