The RT 2020 standard defines the new construction standards applicable in 2020.
Its objective: any new construction will have to produce more energy than it consumes.

Definition of RT 2020

The RT 2020 is the thermal regulation (RT) which will be applicable to all new constructions from, as its name indicates, end of 2020 (and from 2018 to public buildings).
The first thermal regulation was introduced in 1974. The aim was to reduce the energy consumption of new buildings. The objective of the RT 2020 is to implement the concept "BEPOS" (buildings with positive energy), conceived within the framework of the Sustainable Building Plan. They are thus qualified because they produce more energy (heating, electricity ...) than they consume to function.
The RT 2020 is a follow-up to the RT 2012.
The RT 2012, planned by the Grenelle Environment Forum, was aimed at dividing the energy consumption of new buildings by a factor of 3, ie a maximum of 50 kWh / m2 per year, limiting heating, air conditioning, lighting, hot water and ventilation.

RT 2020 and insulation

To produce more energy than it consumes, a RT 2020 house must on the one hand make the most of the free energy sources and on the other hand minimize its energy needs. This includes improved insulation of the enclosures of the frame and intelligent energy management. Home automation therefore has an important role to play.

RT 2020 and passive house

A RT 2020 house is no more than a passive house in more powerful. Indeed, a passive house is a house that produces as much energy as it consumes. A RT 2020 house must exceed its energy needs through the production of renewable energies. The surplus energy can be returned to the public grid.
A passive house has an overinvestment of 5% to 10% compared to a traditional house, according to Ademe Haute-Normandie. 'Since the operating cost is lower, over-investment is depreciated well before the end of the building's occupation,' the organization says.

RT 2020 and positive house

A positive house, or positive energy building, is the concept which RT 2020 aligns to. These buildings consume less energy than they produce, due to technical solutions (for roofs, walls, windows or verands) allowing the accumulation of heat and the production of electricity. The need to eliminate thermal bridges (often weakly insulated and usually between two walls such as a roof and wall) by means of insulation from the outside, for example, or where there are detached facades of structures. 

RT 2012 and RT 2020: what's the difference?

The standard RT 2012 is the latest thermal standard as of RT 2020.

The main deifference between the RT 2012 and the RT 2020 is the energy expenditure limits. While the RT 2012 corresponds to a ceiling of  50 kWh/m²/year, namely the average value of the low energy building lable, the RT 2020 requires the production of energy to be greater than consumption. The expenditure must therefore be less than 0 kWh/m²/year.

Useful links on the RT 2020 :
http://www.rt-2020.com/
http://www.les-energies-renouvelables.eu/conseils/reglementation-thermique-2012/lobjectif-de-la-reglementation-thermique-2020/