Caeli: cooling buildings with low-carbon air conditioning

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1. Global warming, overheating in buildings and energy-hungry air conditioning: a vicious circle  

Rising temperatures and outdated air-conditioning systems 

Climate change over the coming decades will lead to periods of high heat and heatwaves, which will have an impact on overheating in buildings and their energy consumption in the summer. In 2019, ADEME reported that 22% of households were equipped with one or more cooling systems, compared with 14% in 2016, an increase of 50% in 3 years. By 2050, the French Agency for Ecological Transition (ADEME) predicts that 1 in 2 homes will use air conditioning. In Europe today, the air-conditioning market already totals 8 million units sold each year, worth 5 billion euros. 

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Although the basic idea behind an air conditioner is to blow out cold air, it does this by absorbing warm air from the room and releasing it outside. This makes conventional air conditioners an unacceptable solution because of their colossal carbon footprint: they consume a lot of energy, use refrigerants with high greenhouse gas emissions, and produce heat. Today, the carbon footprint of air conditioners worldwide is the same as that of Japan. Even worse: by 2050, they will consume as much electricity as China currently does. It's a vicious circle with far-reaching consequences that Caeli Energie is determined to put an end to. 

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The main challenge concerns multi-family dwellings. More equipped with air-conditioning systems than single-family homes, they are also more likely to be found in urban environments, and thereby exposed to Urban Heat Islands (UHIs). A study by the French National Center for Meteorological Research (CNRM), published last July, looked at the widespread use of air conditioning in the Paris region. The results are clear: the local temperatures are rising by up to 3°C as a result of the hot air released by air-conditioning systems.

Regulatory framework accelerates response to this challenge

Following France's 2003 heatwave, which led to the deaths of over 15,000 people,keeping people cool has now become an obligation : the government issued adecree on August 13, 2004, amending the April 26, 1999 decree, establishing the specifications for the multi-year agreement provided for under Article 5-1 of Law no. 75-535 (June 30, 1975) on social and medico-social institutions, to ensure that all nursing homes are equipped with cool rooms. The same approach was proposed for healthcare establishments. 

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It has therefore become a matter of urgency to protect people at risk during peak heat periods, particularly in nursing homes and hospitals, in facilities with critical equipment and in contest or examination rooms. 

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In addition, the Law of March 30, 2023 introduced a 5-year derogation from public procurement law to massively increase the energy efficiency of public buildings. 400 million square meters of public buildings (300 million square meters for local authorities) are scheduled for renovation.

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Benefits and subsidies will be provided to projects that choose companies compatible with this law, rather than obsolete air-conditioning systems. The new standards will therefore encourage the expansion of new, much more environmentally-friendly solutions. 

The need for disruptive innovation in the existing air-conditioning market

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Over the next thirty years, an average of four air conditioners could be sold every second, according to the International Energy Agency. Air conditioning is becoming a real environmental threat: the time has come to change models. 

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The most urgent step to take would be to ensure that all new air conditioners are much more energy-efficient. All units are different, and some are up to 25% more energy-efficient. But is this enough? There is a growing need for projects championing an 'air-conditioning of the future'. 

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Caeli is one of them.

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2. Substituting environmentally harmful air conditioning imports with French-made low-carbon cooling systems.

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Refrigeration systems with high energy efficiency and low environmental footprint

Caeli's mission is to offer a sustainable alternative to conventional air conditioning. To achieve this, the Isère-based company designs and manufactures cooling systems with a low environmental footprint: they consume 5 times less energy than conventional air conditioners and operate without refrigerants. What's more, they do not release any heat outside or increase the UHI effect. 

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This innovative, patented solution, developed at the French National Centre for Scientific Research
(CNRS), uses the energy produced by the changing state of water as it evaporates. In practice, this process is naturally enhanced to produce cooler air than any other existing evaporative system.  

At the heart of the Caeli project: innovation, performance and relocation

i) Technological innovation 

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The main attraction of this technology lies in its apparent simplicity: the only moving parts are fans, and the functional core uses no chemicals or rare metals to operate, just water and air. Only a handful of companies in the world have mastered this cycle, and Caeli Energie is currently the company with the best track record in this field. 

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ii) Energy performance

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Caeli cooling systems deliver remarkably higher energy and thermal performance than conventional air-conditioning systems. Their coefficient of performance (COP) is over 17, which is 4 times higher than conventional air conditioning. 

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iii) Industrial relocation

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Beyond the CO2 issue lies another objective: Caeli aims to relocate the production of the air conditioning system. Their workshops, located in Grenoble, provide 100% of their production. 

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To achieve this, they are focusing on 2 priorities: 

• simple, proven technologies
• a network of strong local skills

Behind the project, a skilled team driven by long-term ambition

Behind the project are Rémi Pérony (CEO), who is deeply involved in the company's strategy and development, and Stéphane Lips, a former researcher at the Centre for Energy and Thermal Sciences of Lyon (CETHIL), who developed the Caeli product. He is in charge of the R&D part of the project. 

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The Caeli Energie team is made up of men and women who share a strong commitment to the climate cause, and who are driven by values of efficiency, goodwill and fairness. 

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3. A sustainable solution to the recurring problem of summertime overheating

Caeli technology: revolutionary heatless air conditioners

The technology developed by Caeli is based on indirect adiabatic dew-point cooling. The dew point is the temperature at which air must be cooled to become saturated with water vapor, thereby initiating condensation. This cooling solution is based on the Maisotsenko cycle, and allows an air mass to be cooled below its humid temperature. 

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To optimize the Maisotsenko cycle, Caeli Energie's R&D teams have developed a patented process that maximizes the heat exchange surface between the air and the wet surfaces, resulting in high compactness and unique performance. 

Proven results in terms of environmental impact

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Caeli's value proposition is to transform and improve our living spaces with the least possible impact on the environment. This is achieved by following 2 objectives: 

First objective: drastically reduce the environmental footprint of air conditioning

Tunring on a Caeli product reduces CO2 emissions by 85%. In a few years' time, this would translate into 250,000 tonnes of CO2 not being emitted into the atmosphere. 

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Caeli cooling systems : 

• do not use refrigerants, and therefore have no environmental impact through greenhouse gas emissions
• use 5 times less energy than conventional air conditioning
• operate without an external cold pack, making them easy to integrate and preventing warm air from being blown outside

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Tangible, measurable results:

To quantify this environmental benefit, a comparative life cycle analysis (LCA) was carried out using the OPEN LCA tool. The results speak for themselves: deployment of the solution in Europe would cut air-conditioning-related carbon emissions by a factor of 3 to 6.

Second objective: increasing yields for ever greater environmental efficiency

Thanks to its unique technology, the energy efficiency of the Caeli air-conditioning system increases as the temperature difference between inside and outside rises. 

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This solution offers : 

1/ High energy efficiency : for equivalent use, and compared with conventional air conditioning, a Caeli system consumes 5 times less electricity.

2/ Water savings : thanks to its energy efficiency, Caeli technology requires very little water compared with a conventional air conditioner.

3/ No impact on humidity : conventional air conditioning dries out the ambient air, but Caeli does not affect the absolute humidity (water content) in the room concerned.

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For all these reasons, we are very proud to allow Caeli Energie to fund the creation of a pilot line to enhance its production capacity, systems production operations, and strategic recruitment.

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The Caeli project as told by its co-founders :

Press coverage:

• Caeli Energie wants to deploy its low-carbon cooling systems, Les Echos
• Caeli Energie raises 10 million euros to deploy its "green" air conditioning systems, Maddyness

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