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Efficient cooling with natural technology
Adiabatic evaporative cooling is the way forward
Sustainability
The relevance of natural cooling systems for sustainable buildings
The increasing relevance of sustainability in building services engineering means that conventional air conditioning systems are often no longer the first choice when it comes to the efficient operation of ventilation and cooling systems. The challenge of minimising energy consumption and environmental impact has encouraged the search for more environmentally friendly alternatives. One of these alternatives is adiabatic evaporative cooling, a process that favours environmentally friendly cooling without the use of F-gases. This technology has long been developed by companies such as Menerga and has now become established in ventilation technology.
Adiabatic evaporative cooling offers an opportunity to reduce or even completely replace mechanical refrigeration.
How does adiabatic evaporative cooling work?
With adiabatic evaporative cooling, the need for mechanically generated cooling can be reduced, which means considerable savings, especially in Central Europe.
Adiabatic evaporative cooling is based on the principle of changing the state of the air through the evaporation of water. Evaporation heat is extracted from the air, causing the temperature to drop. This cooling takes place without additional energy input and is therefore particularly efficient.
The process is implemented in indirect adiabatic evaporative cooling, in which the air is cooled in the exhaust air humidification system. This cooled exhaust air then transfers the cold to the outside air via a heat recovery system, making the supply air for the room cooler.
Changing environmental policy and the future of building cooling
Climate change has led to stricter requirements for the efficiency of air conditioning systems. As a result, there are strict regulations at EU level, such as EU Regulation 2016/2281, which prescribes efficiency limits for mechanical refrigeration systems. The aim is to limit energy consumption and the use of refrigerants with a high global warming potential, such as R407C or R410A. These regulations are an additional reason why systems such as adiabatic evaporative cooling are becoming increasingly important.
The EU has developed specific requirements for air conditioning systems to improve efficiency and reduce the use of environmentally harmful refrigerants.
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Marketable systems
As already described, a variety of approaches for implementing indirect adiabatic evaporative cooling in central air conditioning units have now become established. The five most important commercially available solutions in terms of technology, efficiency, advantages and disadvantages are briefly presented below.
The adiabatic cooling efficiency is used as a criterion for the performance of the various systems. Based on the fact that the theoretically minimum achievable supply air temperature corresponds to the wet bulb temperature of the exhaust air, this is defined as follows:
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| System | ϕ adia | WRG class according to EN 13053:2017 | |
|---|---|---|---|
| 1. | Exhaust air humidification and rotary heat exchanger | 70 % | H2 |
| 2. | Exhaust air direct humidification with fresh water and cross-counterflow recuperator | 75 % | H2 |
| 3. | Exhaust air direct humidification with high-performance KVS | 90% | H2 |
| 4. | Exhaust air direct humidification with circulating water and counterflow recuperator | 91 % | H1 |
| 5. | Exhaust air direct humidification with circulating water, dew point cooling and counterflow recuperator | >100 % | H1 |
Simple system with an adiabatic cooling efficiency of approx. 70 %. Ideal for systems with high air flow rates.
Here, evaporative cooling takes place directly in the recuperator, which increases the cooling capacity and requires less investment in additional humidification systems.
Enables separate treatment of extract air and supply air, which is particularly beneficial in environments with high hygiene requirements.
The efficient use of the counterflow principle maximises the cooling capacity and achieves a high adiabatic cooling efficiency of over 90 %.
The system achieves temperatures below the wet bulb temperature. This enables cooling that theoretically works without mechanical cooling.
The choice of a suitable system depends on the respective conditions and the efficiency target, but all systems offer significant savings potential compared to conventional ventilation solutions.
Efficiency and energy monitoring
A Menerga system with the AdiabaticzeroGWP system provides an example of the efficiency of adiabatic evaporative cooling. Here, the outside air is cooled by up to 14 °C, which enables stable operation in summer without additional mechanical cooling. The system is controlled via a comprehensive monitoring system such as Menerga Connect, which monitors the system's performance data in real time and ensures optimum efficiency.
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An operating report shows that the system cools at moderate outside temperatures in partial load operation with minimal energy consumption.
When outside temperatures rise, dew point cooling is activated, which lowers the supply air temperature even further.
With adiabatic evaporative cooling, operating costs can be reduced by up to 70 % compared to conventional systems.
Economic efficiency and site dependency
The choice of adiabatic evaporative cooling often depends on the location, as the efficiency of these systems is determined by the evaporation potential. Particularly in regions with high temperatures, this type of cooling can completely replace a conventional air conditioning system. Cost analyses show that the operating costs of ventilation systems with adiabatic cooling are up to 55 % lower than those of conventional systems.
The cost-effectiveness of such systems is further increased as they can dispense with additional cooling generation systems. This has a positive effect on investment costs, system space requirements and life cycle costs. For companies, this means savings when investing in refrigerants, which often have a high GWP value and therefore contribute to reducing the carbon footprint.
By dispensing with mechanical cooling, not only can operating costs be reduced, but the environment can also be protected.
Adiabatic evaporative cooling as a sustainable solution
To summarise, adiabatic evaporative cooling shows that natural cooling with modern ventilation technologies can replace conventional cooling in many areas of application. Menerga and other companies have developed systems that combine this technology with heat recovery, making ventilation systems more efficient and climate-friendly.
The future of building cooling could be shaped by such systems, especially at a time when the use of environmentally friendly cooling technology is becoming increasingly important. Adiabatic evaporative cooling enables stable and sustainable cooling, which not only reduces costs but also minimises the use of environmentally harmful refrigerants.
Saving energy is the most energy-efficient and environmentally friendly solution.
Adiabatic evaporative cooling could set a new standard in ventilation and air conditioning technology, helping engineers, architects and building operators to achieve ecological and economic goals at the same time.