Cooling subsectors


What are the main sectors in which cooling is needed? What is the GHG-mitigation potential per sector?

We encounter cooling in different forms in many places of our everyday life. We are often not even aware of the advantages we gain from it, yet refrigerants and the energy consumption of the appliances are responsible for a considerable amount of emissions that harm our environment. Green Cooling solutions can contribute significantly to achieving the SDGs and thus improve the quality of life of people worldwide. Enter our cool city, explore the different cooling subsectors and learn more about their use, appliances, refrigerants and how they affect everyone in our daily lives.

Click on the image below to discover more about the various cooling subsectors!

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The cooling subsectors

Unitary air conditioning 

Unitary air conditioning (UAC) systems are used to maintain a pleasant indoor climate inside buildings, such as private households, residential areas, business complexes and hotels. This not only leads to better well-being; it also increases productivity. The global stock of air conditioning in buildings will grow to 5.6 billion by 2050, compared to 1.6 billion in 2018. This corresponds to 10 new ACs sold every second for the next 30 years (IEA, 2018 (opens in a new window)). As a result, global energy demand for air conditioning is expected to triple by 2050. 

Green Cooling solution

One important step is the transition to inverter-type UAC systems. Inverter air conditioners vary their cooling/heating capacity by adjusting the power supply frequency of their compressors. This controls the refrigerant flow rate, which consumes less electricity and lowers indirect emissions. In order to reduce direct emissions, the natural, low-GWP refrigerant propane is increasingly used. However, most appliances still run on the harmful refrigerant HFC-410A, which is 2088 times more damaging to the climate than CO2. The combination of higher energy efficiency and the use of a natural refrigerant can lead to a reduction in CO2 emissions of around 60% compared to current applications.


Chillers are often used to cool large buildings, especially office complexes, retail stores and hospitals, but they are also used in industrial processes such as plastics and rubber production or food processing. The equipment contains water, which is cooled, and is then distributed over longer distances. 

As chillers are very large installations, sustainable alternatives can contribute significantly to reducing energy consumption, protecting the climate and ensuring sustainable urban development. Compared to UAC, direct emissions from air conditioning chillers are 20 times higher. The main reasons are their high refrigerant content, relatively high leakage rates and low recovery efficiency.

Green Cooling solution

A combination of energy efficiency measures and natural refrigerants can reduce the total emissions of chillers by 40% in industrialised countries and by up to 60% in developing countries. One environmentally-friendly refrigerant option is propane. It can not only reduce direct emissions but also improves energy efficiency of the chiller by 10-20%. Additional measures for high energy efficiency are replacing components with highly efficient parts such as heat exchangers or inverter compressors, the strategic positioning of the device, regular maintenance, minimisation of leakages and a general reduction of cooling needs in new buildings.

Mobile air conditioning

Mobile air conditioning systems (MACs) are installed in cars to keep drivers comfortable, cool and alert for safe driving. Some MACs have a cooling capacity that could even cool a small apartment. Their fuel consumption is estimated at 3-7% (up to 20% in very hot, humid regions) of the annual fuel consumption of vehicles (ICCT, 2019 (opens in a new window)). About 81-88% of these emissions are indirect due to the energy used to operate the MAC. The direct emissions result from refrigerant leakages during manufacture, operation, maintenance, repair and at the end of the service life. Although the EU, Canada and Japan have already banned the use of refrigerants with a GWP above 150 in MACs, the predominant and very harmful R134a (with a GWP >1300) is still used in millions of older vehicles.

Green Cooling solution

A change to climate-friendly refrigerants can almost eliminate 12%-19% of MAC emissions. In addition, the use of systems with improved efficiency and low leakage, load reduction and powertrain optimisation strategies can reduce GHG emissions by approximately 70% over the lifetime of the system.

Hydrocarbons are not yet considered a viable refrigerant option by car manufacturers due to flammability concerns. Nevertheless, hydrocarbons can be an option for electric vehicles with hermetically sealed refrigerant systems. In such systems, propane works efficiently and safely. Since air conditioning is now a standard feature in vehicles and the demand for cars is constantly increasing, it is even more important that the automobile industry analyses, develops and implements climate- and environmentally friendly solutions.

Domestic refrigeration

A refrigerator is one of the first appliances purchased when electricity becomes available. Almost every household in developed countries has at least one refrigerator as it is the most convenient and safest way of preserving food. As a consequence, the number of refrigerators used in developing and emerging countries is expected to double to almost two billion over the next 15 years (opens in a new window).  While the transition to natural refrigerants is almost complete in European countries and is underway in emerging markets, there is still room for improvement in developing countries. In these regions, the task of transforming the market to climate-friendly and energy-efficient domestic refrigerators is particularly important and can achieve energy savings of more than 60%.

Green Cooling solution

A climate-friendly refrigerator uses refrigerant and foam blowing agent gases with a GWP of 20 or less and no ODP. The most environmentally-friendly option for refrigerators today is the hydrocarbon refrigerant isobutane (R600a), which has a very low GWP of 3. Old refrigerators often rely on climate- and ozone-damaging refrigerants. In some developing countries like e.g. Ghana, the second-hand trade of those old appliances is prohibited, and the purchase of climate-friendly and energy-efficient new refrigerators is (sometimes also financially) encouraged. In the long term, the high acquisition costs are offset by lower energy consumption. 

Commercial refrigeration

Commercial refrigeration systems are mostly used to keep perishable goods fresh or frozen. They are installed in food retail outlets (supermarkets, discount stores, butcher’s and bakeries), cafés and restaurants, nurseries, catering facilities (hotel, canteen) and other areas. These systems account for 40-50% of a supermarket's or convenience store's total energy use. Depending on the field of application and purpose, many variants can be distinguished. Basically, a distinction can be made between centralised and decentralised systems. In centralised systems, several refrigeration points are served by a single cooling system. Although the refrigeration units are located in the sales area, the actual system is usually in a separate machine room. In decentralised installations, each appliance is driven by its own cooling system.

Green Cooling solution

The use of hydrocarbons in commercial refrigeration is common today, especially in new appliances. However, there are still many devices that operate with climate-damaging HFCs. In decentralised systems using hydrocarbons (isobutane or propane), the energy consumption is 10-15% lower than comparable appliances using HFCs (opens in a new window). For beverage coolers with hydrocarbons the value is even 30% lower. Centralised systems differ a lot in the choice of refrigerant, the type of refrigeration distribution and the type of condenser cooling. Cooling solutions using ammonia or CO2 are the most environmentally-friendly and energy-efficient option. However, some characteristics of those hydrocarbons such as material compatibility, toxicity, and flammability have so far mostly prevented the use of ammonia for commercial applications. 

Industrial refrigeration

Safe food is fresh food, and fresh food is refrigerated food. But no matter whether for the food, beverage, pharmaceutical or petrochemical industry: Industrial refrigeration ensures that products stay cool in the process facility and in the warehouse. Due to the wide range of applications and the manifold fields of use, industrial refrigeration has large potential to reduce emissions.

Green Cooling solution

The natural refrigerant ammonia is the dominant refrigerant for industrial refrigeration today in most developed countries. It is the least expensive of the common refrigerants and highly energy-efficient. Ammonia occurs naturally in the environment and is available in abundant quantities. CO2 systems have also proven their cost efficiency and, along with ammonia, are state of the art. However, until now, technologies with ammonia and CO2 are a privilege of rich countries as the initial cost of equipment is very high in comparison to other systems. Furthermore, there is a lack of trained technicians who know how to safely handle natural refrigerants. Proper information and training of technicians can counteract this. 

Transport refrigeration

In our globalised world, products and food travel continuously, whether by ship, plane or truck. During transport, perishable goods must be kept refrigerated. In fact, 20% of the world's food is spoiled by poor cooling, mainly due to an interruption to the cold chain. It is estimated that more than 4 million refrigerated transporters of all sizes secure the cold chain (UBA, 2017 - German only) (opens in a new window), but at the same time it is often very harmful to the environment.

The cold room temperature in refrigerated trucks is maintained by a transport refrigeration system which cools or sometimes also heats the interior of the insulated refrigerated body depending on the ambient temperatures. In these transport refrigeration systems, the climate-damaging refrigerants R404a or R410a are dominantly used today.

Green Cooling solution

Climate-friendly and energy efficient alternatives are natural refrigerants with very low GWP, such as propane and carbon dioxide. Similar to MACs, the refrigerant leakage with rates up to 20-30% per year is high. This is caused in particular by constant vibrations during operation and difficult road conditions which lead to lose connections. In order to achieve complete optimisation in the field of transport refrigeration, the following aspects should be considered:

  • Reduce leakage, as fully charged systems are more effective
  • Improve energy efficiency using two-stage refrigerant circuits
  • Optimise components (e.g. compressor, heat exchanger)
  • Use inverter technology coupled with an alternator to improve part-load efficiency
  • Reduce cooling needs by improving the insulation of the vehicle, optimising delivery routes and proper handling of goods
  • Optimise the dimensions of refrigeration units based on size, insulation and use of vehicle