Evaporative cooling provides a highly effective and environmentally responsible indoor climate solution for the industry. Yet many people are still suspicious of its cooling efficiency and instead stick to what they know: conventional air conditioning. This is unfortunate, as conventional air conditioning leaves a massive carbon footprint - especially in comparison with two-stage evaporative cooling.
This page provides a clear comparison between evaporative cooling and air conditioning - find out what advantages work best for you.
N.B.: This page refers to evaporative cooling and two-stage evaporative cooling. Two-stage evaporative cooling employs an improved adiabatic technique with higher efficiencies, lower supply temperatures and reduced humidity. The air conditioning we refer to is mechanical cooling used to remove heat and control for humidity through vapour compression.
Two-stage evaporative cooling uses fresh air to cool and ventilate multiple times an hour. This air is filtered to remove any dust or allergens.
Air conditioning generally cools recirculated indoor air to avoid extra energy use needed to cool and dehumidify incoming outdoor air.
Two-stage evaporative cooling uses only 10% of energy compared to conventional air conditioning. 95% of the cooling capacity is provided through the natural process of water evaporation. The motor-driven fan that regulates the adiabatic process requires 1 kWh of electricity and provides up to 40 kW of cooling power.
Air conditioning uses 90% more energy to cool and ventilate than evaporative cooling. The cooling power derives from vapour compression in a closed system rather than simply evaporating water. In a further comparison, mechanical cooling systems require 1 kWh of electricity to produce only 2 to 4 kW of cooling power.
On hot days the cooling efficiency of the two-stage evaporative cooling system increases. Warmer temperatures allow for more moisture in the air, and thus the system can evaporate more water. And the more water is evaporated, the more cooling power the system can provide without increasing its energy consumption.
The hotter the outside temperatures, the more energy is needed for conventional air conditioners to achieve the desired indoor temperature. With the global temperature increase, the window for conventional air conditioning to function energy-efficiently is becoming smaller.
Direct evaporative cooling systems can add too much moisture to the air when cooling down to the desired temperature. Two-stage evaporative cooling will provide up to 70% less humidity. In a room, this will result in a humidity level between 40% and 60%. This humidity level helps us fend off viruses and provides comfort against dry eyes and an itchy throat.
Air conditioning dehumidifies the air. Deep cooling causes the moisture in the air to condense on the cold evaporator. The cooled air then contains less moisture. Comfortable in terms of temperature and humidity, but not always healthy. Our immune system cannot defend itself against viruses in dry air while the pathogens thrive. In addition, dry air can also cause discomforts such as an itchy throat or irritated eyes.
The world’s cities are heating up at twice the global average rate due to rapid urbanization and the urban heat island effect. Evaporative cooling releases process air at low temperatures, thus having a positive impact on the growing problem of “urban heating”.
By 2100, many cities across the world could've warmed up as much as 4°C if GHG emissions (CO2) continue at high levels. Air conditioners, additionally, release high temperatures from their condenser, negatively impacting the build-up of urban heating.
Evaporative cooling uses nature’s most potent refrigerant as its cooling agent - water! With an exceptionally high latent heat of vaporisation (2501 kJ/kg at 0 °C), evaporating 1 m3 water generates as much as 695 kW of cooling power. The evaporated water will finally end up in the air and at a later stage come down as rain. Traditional air conditioning technology would demand at least 250 kWh to deliver the same cooling power.
Nowadays, air conditioning uses "less" damaging chlorine-free refrigerants like hydrofluorocarbons as its cooling agents. These refrigerants are continuously evaporated and condensed in a closed system to achieve the desired cooling. This process needs up to 90% more energy than a two-stage evaporative cooling system. Also, regular refill has to be taken into account to avoid reduced efficiency, as some of the refrigerants will escape into the open air. It should not be forgotten that water is also required to generate electricity. Most of the electricity is produced by power plants using oil or coal and at least 10 liters of freshwater per kWh is needed for steam to run the turbines.
Evaporative cooling is a physical process based on water evaporation, meaning that relative humidity affects the effectiveness of the chosen system. The hotter and dryer a climate is, the higher the performance of an evaporative cooling system. In a tropical climate, though, the system might be less efficient in cooling. However, indirect/direct evaporative cooling systems hold their performance far better than direct systems in more humid regions, such as coastal areas, during humid hours.
Air conditioning allows for comfort in all climates. In terms of relative humidity, AC systems are not affected in their efficiency. However, the higher the outside temperatures, the more energy is needed to provide the required cooling capacity.
The trade-off here is whether to spend 90% more energy on even cooling all year round (AC) or to save up on 90% energy and experience slightly less efficient cooling, only a couple of hours a year (evaporative cooling).
In this interview, Kor, our commercial director, explains why preconceptions about adiabatic cooling with indirect/direct adiabatic cooling are a thing of the past.
Good ventilation, filtration and humidity are crucial against the airborne spreading of viruses in the workplace -- even after COVID-19. Learn more in this blog
In this blog, we explain why water is an excellent alternative to the ozone-depleting R-22 refrigerant in conventional air conditioning, how water-based cooling works. Furthermore, we’ll show statistics on sustainability benefits and saved CO2 emissions.