段新星 Duan XinXing

The French hate air conditioning. So Paris built a 120-kilometre machine under its streets for producing cold. It’s called Fraîcheur de Paris, and it does for summer heat what district heating did for winter: centralise the problem. Instead of every museum, office, hotel, hospital and shop bolting its own cooling plant onto the building, Paris moves cold through pipes. The network sends water chilled to 2 to 4°C through buried supply lines. The water enters a connected building, absorbs heat through an exchange station, then returns at 12 to 14°C to be cooled again. It essentially functions with two pipes. One carries the cold out, the other carries heat back. The production plants cool the circuit from 12°C to 4°C. Some sites use the Seine as a heat sink. In colder periods, the system can use the river’s own temperature for free cooling, which means the machines work less and the electricity demand drops. The Seine water doesn’t become the building water. It stays separate, passing temperature across heat exchangers. The scale is pretty strange when you see it written down though. It's got 15 production sites, 4 storage sites, 120 km of underground network with 924 subscribers. This has resulted in 7 million square metres cooled, and 493 GWh of cooling sold. A cold utility running beneath one of the densest cities in Europe. The Forum des Halles has been cooled this way since 1979. The Louvre since 1986. Galeries Lafayette, Opéra Garnier, Hôtel de Ville, Station F, La Samaritaine and the National Assembly all sit on the same idea. Tourists stand in the Louvre looking at paintings while a municipal cold loop does part of the dull work below ground. The boring part is the breakthrough. Cold can be stored at night in chilled water or ice, then used during daytime peaks. The network is monitored from a control room with more than 125,000 control points. A delivery station inside a building takes 5 to 7 times less space than a standalone cooling installation and avoids the roof and façade clutter that turns cities into compressor farms. That matters because conventional air conditioning solves heat by moving it somewhere nearby. In a dense city, thousands of private machines mean thousands of outdoor units rejecting heat into streets, courtyards and roofs, plus refrigerants, noise, vibration and maintenance spread across every building. Paris’s public cooling network has a stated coefficient of performance of 4, against 3 for a wet standalone system and 2 for a dry standalone system. Against an equivalent set of autonomous installations, Fraîcheur de Paris says the network gives 100% higher energy efficiency, 35% less electricity use, 90% fewer refrigerant-fluid emissions and 50% lower CO2 emissions. The climate backdrop is the real reason this exists. Paris ran a full crisis exercise called “Paris at 50°C” in 2023. Météo-France’s 2050 reference trajectory for France points to heatwave days becoming five times more frequent, hot nights rising sharply in urban centres, and some local extremes around 48°C becoming possible. The city signed a 20-year concession in 2022 with Fraîcheur de Paris, owned 85% by ENGIE and 15% by RATP. The contract is worth a projected €2.4 billion. The plan is to extend the network by 158 km by 2042, add 20 production plants and 10 storage sites, and reach more than 3,000 subscribers, including hospitals, nurseries, schools and care homes. This is basically the infrastructure version of admitting that summer is becoming a public systems problem...

yohaniddawela's tweet photo. The French hate air conditioning.

So Paris built a 120-kilometre machine under its streets for producing cold.

It’s called Fraîcheur de Paris, and it does for summer heat what district heating did for winter: centralise the problem.

Instead of every museum, office, hotel, hospital and shop bolting its own cooling plant onto the building, Paris moves cold through pipes.

The network sends water chilled to 2 to 4°C through buried supply lines. The water enters a connected building, absorbs heat through an exchange station, then returns at 12 to 14°C to be cooled again.

It essentially functions with two pipes. One carries the cold out, the other carries heat back.

The production plants cool the circuit from 12°C to 4°C. Some sites use the Seine as a heat sink. In colder periods, the system can use the river’s own temperature for free cooling, which means the machines work less and the electricity demand drops. The Seine water doesn’t become the building water. It stays separate, passing temperature across heat exchangers.

The scale is pretty strange when you see it written down though.

It's got 15 production sites, 4 storage sites, 120 km of underground network with 924 subscribers. This has resulted in 7 million square metres cooled, and 493 GWh of cooling sold.

A cold utility running beneath one of the densest cities in Europe.

The Forum des Halles has been cooled this way since 1979. The Louvre since 1986. Galeries Lafayette, Opéra Garnier, Hôtel de Ville, Station F, La Samaritaine and the National Assembly all sit on the same idea. Tourists stand in the Louvre looking at paintings while a municipal cold loop does part of the dull work below ground.

The boring part is the breakthrough.

Cold can be stored at night in chilled water or ice, then used during daytime peaks. The network is monitored from a control room with more than 125,000 control points. A delivery station inside a building takes 5 to 7 times less space than a standalone cooling installation and avoids the roof and façade clutter that turns cities into compressor farms.

That matters because conventional air conditioning solves heat by moving it somewhere nearby. In a dense city, thousands of private machines mean thousands of outdoor units rejecting heat into streets, courtyards and roofs, plus refrigerants, noise, vibration and maintenance spread across every building.

Paris’s public cooling network has a stated coefficient of performance of 4, against 3 for a wet standalone system and 2 for a dry standalone system. Against an equivalent set of autonomous installations, Fraîcheur de Paris says the network gives 100% higher energy efficiency, 35% less electricity use, 90% fewer refrigerant-fluid emissions and 50% lower CO2 emissions.

The climate backdrop is the real reason this exists.

Paris ran a full crisis exercise called “Paris at 50°C” in 2023. Météo-France’s 2050 reference trajectory for France points to heatwave days becoming five times more frequent, hot nights rising sharply in urban centres, and some local extremes around 48°C becoming possible.

The city signed a 20-year concession in 2022 with Fraîcheur de Paris, owned 85% by ENGIE and 15% by RATP. The contract is worth a projected €2.4 billion. The plan is to extend the network by 158 km by 2042, add 20 production plants and 10 storage sites, and reach more than 3,000 subscribers, including hospitals, nurseries, schools and care homes.

This is basically the infrastructure version of admitting that summer is becoming a public systems problem...

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段新星 Duan XinXing

@xinxingduan

21 days ago

反过来问就明白了：历史上哪个朝代的陨落与终结，激发了最持久的怀念与叹息？

@Whisper Hu 🎙️🐱

@WhisperMoonCat

21 days ago

历史上“得国最正”“得位最正”的朝代与皇帝都是谁？ “汉朝、明朝”？ “曹丕、赵匡胤、朱棣、李世民”？

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段新星 Duan XinXing

@xinxingduan

21 days ago

看到喷比特币成为一种新的政治正确和时尚潮流；持有者噤若寒蝉，生怕发言不当违逆了主流和网络民意被归为老登，抖抖索索地与其进行或真或假的决裂，并附和主流地嘲讽、调侃，这情形着实令人唏嘘。

段新星 Duan XinXing

@xinxingduan

24 days ago

“ 如果你感到绝望，如果你感到被打败，如果你发现自己心不在焉或只关注压迫者的所作所为，而不是你自己能做些什么 —— 这就是敌人在你内心占据领地的表征。”

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段新星 Duan XinXing

@xinxingduan

24 days ago

@Super4DeFi 最好的基建，最__的资产。crypto和天朝形成了某种意义上的同构。

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段新星 Duan XinXing

@xinxingduan

25 days ago

@R2llB @Trend_A9 中医里称这种疗法为“拔火罐”

段新星 Duan XinXing

@xinxingduan

26 days ago

@baibanbaonet @bltayayay @dyakup_ @PerseusLeGrand @gezenhikayeci 好中文的样子，无意偶得之

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段新星 Duan XinXing

@xinxingduan

27 days ago

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xinxingduan retweeted

Dr John Barry @MalePsychology

28 days ago

"While Stewart-Williams argues that there are inherent differences between men and women, he [...] recommends that people choose work and lifestyles that suit their health, gender, and interests." @SteveStuWill https://t.co/5lOxFJgigy

MalePsychology's tweet photo. "While Stewart-Williams argues that there are inherent differences between men and women, he [...] recommends that people choose work and lifestyles that suit their health, gender, and interests."
@SteveStuWill
https://t.co/5lOxFJgigy https://t.co/otUayEkSh5

段新星 Duan XinXing

@xinxingduan

27 days ago

@FutureJurvetson Isn’t this the modern deus ex machina? AI descending to help us make rational decisions.

段新星 Duan XinXing

@xinxingduan

28 days ago

@mranti @baibanbaonet 没选对版本吧，上手的话建议先看斯泰凡. 厄埃绘，周克希译的《追忆逝去的时光》的图像小说（后浪已出了三本）。

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段新星 Duan XinXing

@xinxingduan

28 days ago

我们的敌人不是坏人，而是坏想法。

Brivael Le Pogam

@brivael

29 days ago

Dans le manifeste "techno-optimiste" de Marc Andreessen, il y a une phrase qui m'a marqué : "Our enemies are not bad people – but rather bad ideas." Nos ennemis ne sont pas des mauvaises personnes. Ce sont des mauvaises idées. Prenons Jancovici. L'homme est brillant, sincère, travailleur. Il ne se lève pas le matin en se disant qu'il va nuire à l'humanité. Mais l'idée qu'il porte la décroissance, le rationnement, la frugalité érigée en horizon civilisationnel est une idée profondément destructrice. Elle prend des esprits brillants et les transforme en commissaires politiques d'un futur appauvri. Et le plus fascinant, c'est ce que cette idée fait aux gens qui l'adoptent. Dans mon entourage, une grosse partie de mes amis est sur cette ligne décroissantiste, avec tout le package qui va avec. L'argent c'est mal mais ils en veulent. Il faut moins prendre l'avion mais ils rêvent de voyager partout. Il faut consommer moins mais ils ne renoncent à rien de ce qu'ils aiment vraiment. Et tous ont un point commun : ils sont déprimés. L'un d'eux m'a même confié qu'il était sous antidépresseurs. Ce n'est pas un hasard. C'est mécanique. Quand tu crois que ton désir de vivre, de créer, de t'élever est moralement suspect tu te détruis de l'intérieur. Tu passes ta vie à t'excuser d'exister. Tu vis dans la dissonance permanente entre ce que ton corps veut (plus, mieux, plus loin) et ce que ton idéologie t'ordonne (moins, sobre, immobile). D'où ma théorie : Quand on pense quelque chose de fondamentalement faux décroissance, communisme, extrémisme religieux (de tout ordre) ce n'est qu'une question de temps avant que ça devienne vraiment destructeur. D'abord pour soi. Puis pour les autres. Les mauvaises idées tuent. Lentement chez ceux qui y croient, brutalement chez ceux qui les subissent. C'est pour ça que la bataille des idées n'est pas un luxe d'intellectuel. C'est la bataille la plus importante de notre époque.

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