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What is the difference between extraction and free cooling?

5 min read
Dantherm building

There are several technology differences between extraction cooling and free cooling solutions, but the overarching one is that free cooling is capable of generating more savings and keeping a cleaner enclosed environment than extraction cooling.

Basically, the systems both offer controlled ventilation and contain roughly the same components, i.e. a fan, a filter and a thermostat or controller. But in practice, we see many differences when it comes to how the components are controlled and dimensioned.

This table compares the two types of controlled ventilation:

Comparing the two technologies


Free Cooling

Overpressure – making sure only filtered air enters the enclosed environment.


Underpressure – allowing air to enter through a filter, but also through any leakage in the room construction.


Filter at air entrance



Overpressure damper


Energy-optimised software implemented in control of the free cooling


Why overpressure?

Dantherm’s free cooling solution uses overpressure to ensure only filtered air enters the shelter. If the room has any cracks or leakages, air will be blown out of this hole – leaving a clean shelter with filtered air.

How important is the control of the system?

In our experience, the control of the system is often decisive to the performance. It can mean the difference between reaching adequate or astounding savings. At Dantherm, we use our own controller technology which is based on our in-house long-standing know-how of thermodynamics combined with real-life experience from working with our customers. Add to that the fact that we are now on generation 5 of our free cooling solution. Each of the generations contain our accumulated knowledge and learnings since the predecessor.

Is the fan important?

Yes – the choice of fan is very important, and it should be dimensioned according to the cooling demand, how powerful the fan is and how it can be placed physically on site to generate sufficient air movement.

What is total heat management?

Our experience from years in the global telecom industry is that sites are often equipped with systems from different cooling and heating vendors. Unfortunately, we have often seen these systems conflicting.

Therefore, Dantherm combines existing systems with an intelligent, energy-saving control strategy. Many systems provide total heat management, but efficient total heat management makes the difference.

See our full range of energy-saving free cooling solutions.

Contact me for an energy savings calculation based on your specific site conditions.

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