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Early Stage Startup


Change the way of cooling!


Elevator Pitch

Coolar develops a refrigerator that cools with heat instead of electricity.

All our refrigerators at home need electricity.
Over 1.2 billion people in the world do not have access to electricty, and therefore no cooling.
This is especially severe, where lifesaving medicine or vaccines have to be stored at cold temperatures.
Up to 75% of vaccine shipments are damaged because of insufficient cooling in developing regions today. Despite medical refrigerators selling for over 4000 Euros per unit.
The resulting economic losses are in the billions of Euros every year.

The Coolar refrigerator can solve this problem, by cooling independent from electrcity and instead with abundant heat from the sun.
We have built a functioning prototype and are cooperating with industry partners and developmental organisations like Doctor's Without Borders to bring our solution to market.

In the future, we want to provide sustainable cooling whereever excess heat capacities are easily available and cheaper than electricity.
This includes island resorts, agricultural businesses, and also households with solarthermal hot water or district heat access.
Mobile solutions are also possible and can enable sustainable cold trucks, refrigerators for camper vans, cold boxes and many more sustainable cooling applications.

We are looking for investment to be able to put the finishing touches on our product, pilot it with our partners in Africa and South Asia and to then enter series production.

We are looking forward to meet you during this year's Ecosummit!


Coolar is developing a compact size refrigeration system that cools with heat instead of electricity by utilising the principle of adsorption.
It allows tapping into abundant heat energy from the sun, or any other economical heat source instead of requiring CO2-intensive, expensive or in remote regions often unavailable electricity.
Coolar’s adsorption cooling system will enable health facilities, businesses and households to preserve lifesaving vaccines, medicine and nutrition in a reliable and eco-friendly way by providing innovative refrigerators that run independent from the electricity grid and are close to carbon neutral.
It is an elegant solution, that turns the source of the problem - heat that jeopardizes the safe delivery of medicine and vaccines that have to be cooled - into the energy source that powers the solution - a heat powered refrigerator.

Why we are ecofriendly

The Coolar adsorption refrigeration system allows utilising low-carbon heat sources like overcapacity from solarthermal installations, heat from cogeneration, or district heating. In terms of reduction of the environmental footprint we estimate that Coolar can reduce carbon emissions by over 60% or 1.44t per device. These estimates are based on a domestic solar hot water system as the primary heat source in a German household. If we calculate emissions savings for countries with higher solar irradiation even larger savings are possible.
As cooling applications are already responsible for about 10% of global CO2 emissions today - more than 4 times the amount of air travel - sustainable cooling technology like Coolar's is of utmost importance. This is especially true in the emerging global South, where warmer climatic conditions will lead to even higher energy consumption for the sake of cooling as more and more Southern countries industrialise.

Coolar's system furthermore does not only save CO2 emissions, but it has also achieved powering the cooling cycle with neither hazardous substances, nor any moving parts that would reduce the system's durability due to wear.

The system evaporates purified water in a low pressure environment and amplifies the resulting evaporation cooling effect via vapour adsorption onto the silicagel's surface. Purified water is the most natural cooling fluid out there, and a lot easier on the environment that the cooling fluids used in conventional compression refrigeration cycles. Silicagel is a completely non-hazardous sediment, that is comparable to little glass pearls or sand, when thrown away.
Due to the nature of the adsorption cooling process, no mechanical parts like compressors are required and results in the system's high durability and makes it possible to run it without hazardous lubricants that are used in compressors.

(Here's a great 1.5 minute animation by The Guardian on the importance of sustainable cooling technology: youtu.be/_7EgYOpcYc0#)

Latest News

Coolar won the finals of the intenational social entrepreneurship competition "The Venture" in New York in July 2016 and received a share of the USD 1 million prize money.

With that Coolar financed the development of its most recent prototype:
a hot water powered adsorption refrigerator with a volume of 180l. The prototype was completed in Q4 2016 and tested extensively with promising results by a medical refrigeration industry partner in Q1 2017.

In Q1 2017 the Coolar team also demonstrated it's technology to 5 health centres in the Turkana region of Northern Kenya, where off-grid cooling of medicine and vaccines poses a critical challenge. The health centre visits and interviews with the staff, guided by Kenyan Ministry of Health officials, confirmed the product-market-fit of Coolar's refrigerator concept.

Currently Coolar is raising its first round of investment to finance putting the finishing touches on the product and initiating a small series production.

Stay up-to-date by following us on social media:

Or contact us via email to christoph@coolar.co


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Version History

2017-04-10 13:44:46 - changed video to 'Coolar - The Venture - finalist video: https://www.youtube.com/watch?v=zJW9OmYX-zE What is...'

2017-04-10 13:44:13 - changed video to 'https://www.youtube.com/watch?v=zJW9OmYX-zE https://www.youtube.com/watch?v=IVH4Sl1u1YU'

2017-04-10 13:37:00 - changed social-impact to '- Improved primary healthcare in remote regions with unavailable or unreliable electricity supply, via electricity...'

2017-04-10 13:36:36 - changed economic-impact to '- Cost savings for reliable refrigeration due to tapping low cost heat sources instead of expensive or unreliable...'

2017-04-10 13:35:56 - changed environmental-impact to '- At least 60% CO2 emissions savings compared to conventional refrigerators. - Water based system without hazardous...'

Coolar is ECO17 Award Nominee.





EUR 1 million

Grants Raised

EUR 200,000


Julia Römer - Co-founder responsible for technology development
Julia is an industrial engineer by training and the inventor of the Coolar adsorption refrigeration system. Together with Arno she initiated the project in the summer of 2014. She has previously developed patents for industrial-scale providers of alternative cooling technology and is furthermore very active in sustainability and environmental protection related advocacy. She is a member of the board at Germany's largest environmental NGO, the BUND (Friends of the Earth Germany).

Arno Zimmermann - Co-founder responsible for product development
Arno is an expert in ecologically sustainable product development, which he consulted on during is time at Ernest & Young and principles of which he applied to product development projects that he worked at in Nest Labs (before it got acquired by Google) and Bayer AG. His position at Coolar makes him a serial entrepreneur, as he also was a co-founder of CupCycle - an eco-friendly coffee cup rotation and recycling project - where he and his team realized a succesful exit.

Christoph Göller - Co-founder responsible for business development
Christoph's background is in business, economics and China studies. He has previously worked in product marketing and marketing at Bosch in Taipei, where his team also marketed compressors for cooling applications across the entire Asia-Pacific region.

Kilian Mähne - Co-founder responsible for manufacturing and quality control
Kilian is a talented craftsman that has previously maintained a glider clubs entire fleet of glider planes, is a mechanical engineer by training and contributed most to building Coolar's first prototypes. As an engineer with a focus on automotive technology he is knowledgeable when it comes to large-scale production and quality management and is currently working on preparing the Coolar system for series production.


>50 prospective customers.

Enviromental Impact

- At least 60% CO2 emissions savings compared to conventional refrigerators.
- Water based system without hazardous substances solves disposal and recycling problems.
- High durability due to no moving parts.

Economic Impact

- Cost savings for reliable refrigeration due to tapping low cost heat sources instead of expensive or unreliable electricity.
- Under off-grid conditions independence from expensive diesel fuel for generators or short-lived batteries.
- Potentially enables new cold storage supply chains i.e. for agricultural businesses.
- Assembly of refrigerators with Coolar systems can be set up in target regions and boost the local economy.

Social Impact

- Improved primary healthcare in remote regions with unavailable or unreliable electricity supply, via electricity independent cooling for medicine and vaccines.


Winner of "The Venture" Germany, as well as winner of the global finals of "The Venture" in New York.

Winner of the first Business Plan Competition Berlin Brandenburg (BPW) 2016

Finalist StartGreen Award 2015

2nd prize winner of Darboven IDEE Förderpreis 2015

Coolar co-founder Arno Zimmermann listed on the Forbes 30 under 30 Europe list as one of Europe's leading young social entrepreneurs.

Finalist in the Off-Grid Experts Award 2015 - category: "best new product"

Country of Origin



May 2016




Christoph Göller - Co-Founder / Head of Business Development

Contact Person

Christoph Göller




Energy, Cleantech, Refrigeration, Cooling, Healthcare