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: the Bbio index (bioclimatic need coefficient) is more ambitious and the Cep index (total primary energy consumption coefficient) reinforces its requirements in terms of equipment performance. Let's take a closer look at this indicator and its levers of influence!
Definition of the Cep index
Compared to RT2012, the energy consumption indicator (Cep) inRE2020 still calculates the amount of energy needed to meet the building's requirements. The goal of reducing consumption is achieved byimproving the energy efficiency of equipment. The objective of the Cep is therefore to stop using fossil fuels in new buildings.
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
However, new to the RE2020, the Cep index also takes into account:
- the energy consumption of elevators or escalators,
- lighting for public transport corridors,
- lighting and ventilation in parking lots
Furthermore, the Cep only measures imported primary energy (renewable or non-renewable) needed to meet the building's energy requirements. The indicator therefore does not count self-consumed renewable energy (not considered as imported) or energy exported from the building's plot as energy consumption.
It should also be noted that a flat-rate penalty is applied to consumption in the event of potential summer discomfort (DH discomfort index).
Cep indicator values in RE2020
This indicator is expressed inkWh/m²/year and must remain below the average Cep_Max defined in RE2020.
The pivot values for Cep_maxmoyen for an average building are as follows:
- 75 kWh/m²/year in detached or semi-detached houses
- 85 kWh/m²/year in multi-family housing
The calculation of Cep_max is based on Cep_maxaverage:
Cep_max = Cep_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).
The Cep index is therefore adjusted according to geographical location, average dwelling size, building size, converted attic space, and external constraints category.
Factors influencing the Cep index
Among the factors influencing the Cep indicator, the equipment used in buildings has the greatest impact. Depending on their energy requirements, they either penalize or directly favor the Cep. Gas heating equipment is heavily penalized, while heat pumps are favored (although hybrid solutions are also compatible).
Furthermore, taking summer comfort into account, particularly with the introduction of the DH discomfort index, can impact the Cep. A fixed penalty for cold is applied to the Cep in the event of probable but not excessive discomfort.
With this indicator, RE 2020 broadens its scope, strengthens its requirements for equipment efficiency, and encourages self-consumption of electricity and heat recovery. Finally, RE 2020 introduces an additional index to the Cep: the Cep,nr, which measures non-renewable primary energy consumption.
