It is the city that hosted COP21 in 2015, lending its name to the global climate agreement. That decided to ban diesel engines by 2024, and petrol engines by 2030. That was awarded the 2024 Olympic Games on the strength of an ecology-centred bid. That decided to double the extent of cycle lanes on its territory, bringing it to 1,400 kilometres. And that, thanks to the commitment of its mayor Anne Hidalgo, has led the C40 for years — the network of more than 80 major cities around the world engaged in the fight against climate change.

Paris has taken on a leading role in environmental protection in recent years, going so far as to launch international initiatives such as the one meaningfully named "Air'volution" (the air revolution), shared with the cities of London and Seoul. "Between now and 2020," Anne Hidalgo explained in an interview given to the monthly magazine Alternatives Economiques, "all C40 cities will have established a climate action plan that will enable them to reduce greenhouse gas emissions in line with the Paris Agreement. That is why we are working on a specific programme for our city covering the period 2017–2021: if every urban centre of more than 100,000 inhabitants in the world does the same, we will be able to reduce global emissions by 40 per cent."

Paris wants to cut CO2 emissions by 80% by 2050

The French capital has, in short, made the fight against climate change not only a banner cause but also a tool for planning its own future. It is from this starting point that Mayor Hidalgo came up with the idea of commissioning a very long-term study from the consultancy firm Elioth. The result is a report of no fewer than 368 pages, entitled "Paris changes era", which imagines the metropolis 33 years from now, in 2050: a "chronicle of a foretold revolution" that touches every aspect of city life, from transport to the property sector, from food to waste management.

The scenario put forward by the researchers who worked on the report envisages a reduction in equivalent CO2 emissions of 50 per cent by 2030 and 80 per cent by 2050. This would be achieved primarily through the development of renewable energy and the profound transformation that will need to take place in the construction sector. "By 2050, around 20 per cent of Paris's rooftops will be covered with solar panels," which will mean covering something in the order of 30 million square metres. The resulting electricity production could reach between 1,200 and 1,500 gigawatt-hours per year, meeting around 10 per cent of the city's total building energy needs." Citizens will be able to self-consume the energy and store any surplus through dedicated systems, all on the basis of a bill already passed at national level.

The French capital's street lighting is already 100% renewable

"By 2050, the payback period on the investment for Parisian residents will be well under ten years," the report explains, based on an assumed average lifespan of 30 years for the installations. In addition, new solar thermal panels will make it possible to produce, free of charge, "15 per cent of the hot water consumed in the capital's residential buildings."

To achieve these goals, the City of Paris is already leading by example, equipping the rooftops of public buildings with solar panels, whose total surface area "amounts to five million square metres, or 17.4 per cent of the city's built-up land." Citizens, meanwhile, will be asked to do their part by purchasing energy produced from renewable sources. This is the area where the most progress will still need to be made: while all of Paris's public street lighting already runs on clean energy, only 0.1 per cent of the population has opted for "100 per cent renewable" contracts for private homes. The share is expected to reach one per cent by 2020 and ten per cent by 2050.

https://www.youtube.com/watch?v=tucDqPKCvII https://www.youtube.com/watch?time_continue=2&v=sRudUWG7e7A&has_verified=1

Clearly, this will not in any case be enough to cover the entire energy needs of the urban population. That is why the council led by Anne Hidalgo will participate "in financing renewable sites outside its own territory as well," in order to offset the use of fossil-origin gas. Specifically, the municipality will contribute to the construction of three thousand wind turbines and 50 square kilometres of solar parks (an area equivalent to the entire city).

Sustainable construction and renovations for 75% of urban buildings

Another fundamental piece of the profound transformation envisaged for Paris is the renewal of its building stock. Eighty-five per cent of the city's buildings were constructed before the introduction of the first environmental regulations, which date back to 1974. The plan provides for the renovation of 75 per cent of homes by 2050: "The pace that will need to be maintained is 5,500 buildings renovated per year from the social housing stock and 24,000 from the private stock."

Fortunately, the thick walls of "Haussmann-era" buildings — those designed by urban planner Georges Eugène Haussmann, which are characteristic of the French capital — mean that the oldest buildings do not represent the core of the problem when it comes to energy efficiency. Efforts will need to focus instead on everything built between 1918 and 1974.

As for new construction, 10,000 units per year are planned, with the dual aim of addressing the severe housing shortage and promoting a new approach based not only on thermal insulation but also on the use of biomaterials as an alternative to traditional ones. "By 2020, the first large buildings with a primary timber structure will be delivered in Paris. By 2030, the goal is to triple the use of this material in the sector." To fund all of this, public grants and zero-interest "eco-loans" have been promised, along with tax credit schemes and certification systems to help citizens find their way.

Cars will be halved — and those that remain will all be clean

Another pillar of the energy revolution envisaged for Paris is that of transport. Transport is currently responsible for more than half of the city's total CO2 emissions. Beyond (and thanks to) the restrictions already planned for diesel and petrol engines, the goal is to halve the number of private cars circulating in the urban area, bringing the figure down to 300,000. The idea is to make vehicle sharing the norm: whereas today each car is occupied on average by 1.1 people, the goal is to reach two people per car by 2050.

At the same time, further particularly far-reaching measures are planned: all vehicles in circulation will have to be powered by clean energy sources, and a total and permanent ban on driving will be introduced during weekends and public holidays.

Sustainable food and "compensatory" reforestation

Change, however, also comes through things that only appear to be secondary. Food is a case in point — a question that has not escaped the study projecting Paris into a sustainable future: over the coming decades, 150 hectares of the French capital will be devoted to urban farming, with the aim of promoting zero-kilometre food and the circular economy. This should make it possible to reduce waste production per resident from 500 to 220 kilogrammes a year.

In addition, the city council will support major reforestation policies beyond its own territory: enough trees will be planted to cover an area of 10,000 square kilometres — the equivalent of the region that is home to the capital, Île-de-France. The aim is to offset the five million tonnes of CO2 equivalent that will still be emitted in 2050 and that the study regards as "unavoidable".