One of the objectives of the RE2020 Environmental Regulation is to reduce the energy consumption of new buildings. To achieve this, it reinforces certain concepts that enable this to be measured. Two indices have had their requirements strengthened and a new index has been introduced: the Cep,nr index. So what does it consist of? What are its levers of influence? This article takes a closer look at the Cep,nr index of RE2020!
Definition of the Cep,nr index
The Cep,nr indicator represents the non-renewable primary energy consumption of a building for the same uses as the Cep. It only takes into account non-renewable energy sources used to meet the building's needs. Apart from this point, it is identical to the Cep in every respect.
It is calculated based on the energy consumption of the following consumption items:
- heating,
- cooling (air conditioning),
- domestic hot water production,
- lighting,
- ventilation and distribution equipment
- the energy consumption of elevators or escalators,
- lighting for public transport corridors,
- lighting and ventilation in parking lots
The Cep,nr index does not take into account the consumption of renewable or recovered energy. This new feature therefore encourages designers to reduce the use of non-renewable energy (fossil fuels, electricity) and to make greater use of renewable energy.
Values of the Cep,nr indicator in RE2020
This indicator is expressed inkWh/m²/year and must remain below the average Cep,nr_Max defined in RE2020.
The pivot values for Cep,nr_maxmoyen for an average building are as follows:
- 55 kWh/m²/year in detached or semi-detached houses
- 70 kWh/m²/year in multi-family housing
Calculation of Cep,nr
The calculation of Cep,nr_max is based on Cep,nr_maxaverage:
Cep,nr_max = Cep,nr_maxaverage × (1 + Mcgeo + Mccombles + Mcsurf_avg + Mcsurf_tot+ Mccat)
With:
Mcgéo = modulation coefficient based on the geographical location (geographical area and altitude) of the building
Mccombles = modulation coefficient based on the floor area of converted attic space in the building (new modulation that allows the Bbio requirements to be adjusted to take into account heated areas with a ceiling height of less than 1.80 m (not included in the SHAB))
Mcsurf_moy = modulation coefficient based on the average surface area of the dwellings in the building or part of the building
Mcsurf_tot = modulation coefficient based on the total surface area of the building
Mccat = modulation coefficient based on the category of external constraints on the building (reformulation of categories CE1 and CE2 of RT 2012). Mccat compensates for external constraints that limit the possibilities for natural ventilation of the building by opening windows (Br2, Br3), when this requires the use of an air conditioning system for buildings in the Mediterranean coastal and inland regions (H2d and H3).
Thus, just like the Cep index, the Cep,nr indicator is adjusted according to geographical location, average housing size, building size, converted attic space, and external constraints category.
Factors influencing the Cep,nr index
Several factors can influence the Cep,nr indicator:
- Thermal insulation: Effective thermal insulation of buildings reduces heating and cooling requirements, which helps to reduce the consumption of non-renewable energy.
- Efficient heating and cooling systems: Using more efficient heating, cooling, and ventilation systems, such as heat pumps, condensing boilers, or solar energy systems, can reduce energy consumption.
- LED lighting: Using efficient LED light sources can reduce energy consumption related to lighting.
- Renewable energy: The integration of renewable energy sources, such as photovoltaic solar panels, wind turbines, or geothermal systems, can offset the consumption of non-renewable energy.
- Building envelope management: Effective building envelope design, using materials with low thermal conductivity and appropriate airtightness techniques, helps minimize heat and cold loss.
- Ventilation and heat recovery: Ventilation systems with heat recovery reduce heating requirements by recovering heat from the extracted air to preheat the incoming fresh air.
- Occupant behavior: Educating occupants on best practices for saving energy, such as setting the temperature appropriately, turning off lights, and using electrical appliances responsibly, can influence energy consumption.
- Bioclimatic design: Designing for the local climate, with appropriate window orientation and layout and efficient use of passive solar gain, can reduce energy requirements for heating and cooling.
- Sustainable building materials: Using building materials with low environmental impact, such as bio-based materials, can help reduce the overall carbon footprint of the building.
In conclusion, it is important to note that RE2020 imposes specific energy and environmental performance requirements, and that the combination of these different levers will depend on the specific characteristics of each construction project in order to achieve the objectives of the regulation.
