Efficiency-minded changes in architecture and regulations have created new requirements for energy performance in buildings.

Paris has partnered with utility firm Engie to develop the subterranean cooling network, which it believes is the most sustainable way to cool buildings in light of a marked increase in the use of air-conditioning units.

As building insulation improves to keep pace with evolving standards, more of the heat produced inside buildings by lighting, heating and computers remains there. As a result, cooling is starting to represent an increasing proportion of the overall energy used by buildings.

In addition, the majority of cities experience higher localised temperatures because of an artificial microclimate created by human activities and the use of paved surfaces which absorb more heat.

Jean-Louis Missika, deputy mayor of Paris, announced plans to increase the size of the network yesterday. “We do not want global warming to lead to a profusion of individual air-con units. These are inefficient, polluting and they add to local warming. And they are ugly,” he told Reuters.

The network could set a precedent for how other cities can become more sustainable. More than half of the world’s population lives in cities, with that number expected to grow to 60 per cent by 2030. Around 75 per cent of all energy produced worldwide is consumed in cities.

The pre-existing cooling grid – run by Engie unit Climespace – uses water from the River Seine, but the existing 75km network mainly services hospitals, hotels, museums and department stores. The plan now is to open this network up to small businesses and residential customers.

France has experienced a series of heatwaves in recent summers. On 25 July 2019, the French capital recorded a temperature of 40.6°C – the hottest since records began.

Missika said Paris wants its Climespace cooling network (Europe’s biggest) to cover 100 per cent of the city’s area over the next 20 years, up from around 43 per cent today, and make it available to non-institutional customers.

“It must be possible to connect the cooling grid to residential buildings as well as to small businesses,” he said.

The expansion of the cooling network will be part of the criteria in a new tender for the operation of the network, which for the past 30 years has been run by Climespace. It recorded revenue of €91m (£78m) in 2018.

Paris has a minority stake in Climespace, via Paris urban heating-grid operator CPCU, which is 66.5 per cent owned by Engie and the rest by Paris. Missika said the city plans to organise a tender in 2020, with a view to put a new operator in place by February 2021.

Asked whether it would be conceivable that the tender would not be won by long-time Paris partner Engie, Missika said he expected many firms will want to bid for the 20-year contract.

A study in 2017 found that climate change could have a particularly problematic impact on cities as the heat-island effect could create localised warming 2.6 times higher than surrounding areas.

Efficiency-minded changes in architecture and regulations have created new requirements for energy performance in buildings.

Paris has partnered with utility firm Engie to develop the subterranean cooling network, which it believes is the most sustainable way to cool buildings in light of a marked increase in the use of air-conditioning units.

As building insulation improves to keep pace with evolving standards, more of the heat produced inside buildings by lighting, heating and computers remains there. As a result, cooling is starting to represent an increasing proportion of the overall energy used by buildings.

In addition, the majority of cities experience higher localised temperatures because of an artificial microclimate created by human activities and the use of paved surfaces which absorb more heat.

Jean-Louis Missika, deputy mayor of Paris, announced plans to increase the size of the network yesterday. “We do not want global warming to lead to a profusion of individual air-con units. These are inefficient, polluting and they add to local warming. And they are ugly,” he told Reuters.

The network could set a precedent for how other cities can become more sustainable. More than half of the world’s population lives in cities, with that number expected to grow to 60 per cent by 2030. Around 75 per cent of all energy produced worldwide is consumed in cities.

The pre-existing cooling grid – run by Engie unit Climespace – uses water from the River Seine, but the existing 75km network mainly services hospitals, hotels, museums and department stores. The plan now is to open this network up to small businesses and residential customers.

France has experienced a series of heatwaves in recent summers. On 25 July 2019, the French capital recorded a temperature of 40.6°C – the hottest since records began.

Missika said Paris wants its Climespace cooling network (Europe’s biggest) to cover 100 per cent of the city’s area over the next 20 years, up from around 43 per cent today, and make it available to non-institutional customers.

“It must be possible to connect the cooling grid to residential buildings as well as to small businesses,” he said.

The expansion of the cooling network will be part of the criteria in a new tender for the operation of the network, which for the past 30 years has been run by Climespace. It recorded revenue of €91m (£78m) in 2018.

Paris has a minority stake in Climespace, via Paris urban heating-grid operator CPCU, which is 66.5 per cent owned by Engie and the rest by Paris. Missika said the city plans to organise a tender in 2020, with a view to put a new operator in place by February 2021.

Asked whether it would be conceivable that the tender would not be won by long-time Paris partner Engie, Missika said he expected many firms will want to bid for the 20-year contract.

A study in 2017 found that climate change could have a particularly problematic impact on cities as the heat-island effect could create localised warming 2.6 times higher than surrounding areas.