Evaporative Cooling:
Colt Coolstream N - the natural evaporative cooler

CoolStream N demonstration video

CoolStream N provides low-cost adiabatic / evaporative cooling and ventilation principally for larger industrial premises with higher heat loads, such as power generation plants and other heat intensive industries.

The CoolStream N adiabatic cooler helps keep larger internal spaces cool all year round. It doesn’t need to cost the earth: using the cooling power of water, it’s possible to achieve low energy cooling.

Since it uses natural ventilation, no energy is consumed to power fans. However if it is necessary to boost the air flow and cooling capacity from time to time, optional EC fans can be integrated into the system.

Features and Benefits of the Coolstream N

For a full specification, click here.

  • It has a huge potential geometric face area (maximum of 20 m2 per unit) and high aerodynamic efficiency, thus allowing a big air flow through one unit.
  • Low level inlet draws in cool outside air
  • Option of virtually silent EC fans to boost air flow and cooling capacity
  • Modular design
  • High air quality: uses 100% outside air
  • Adiabatic cooling is up to 90% efficient
  • Low running and maintenance costs
  • Simple and reliable technology
  • Environmentally friendly and safe
  • Free from refrigerants
  • Highest degree of hygiene. Integrated water quality control system and hygiene certificate to VDI 6022.

Applications for the Coolstream N

CoolStream N is well suited to industries such as power generation, plastics, metal, or food, either as a new system or an add-on to existing natural ventilation systems.

CoolStream systems are popular with building operators and owners because of their low initial and running costs and low maintenance.

CoolStream N is based on CoolStream S technology. CoolStream S provides an alternative means of evaporative cooling by using fans to create the air flow.

How adiabatic cooling works

Hot dry air is drawn across wetted media, resulting in an exchange of energy and a significant reduction in the temperature of the air. The warmer the outside temperature, the more efficiently evaporative cooling works.

Efficient and cost effective cooling

Above 30°C, the air can cool down adiabatically by at least 10°C, resulting in very efficient cooling. Evaporative cooling is 4 to 7 times more economical than conventional air conditioning systems, and is achieved with lower initial costs.

Cooling and ventilation in one system

Evaporative cooling involves supplying 100% fresh air and thereby maintains air quality. It is an enhanced input ventilation system, which means it can be used in spring and summer with the cooling function only being operated when conditions dictate. Heat is normally removed at high level via natural ventilators, providing a pleasant temperature at the working area.

Boost your ventilation system with CoolStream N

CoolStream N is particularly effective in large spaces where a purely natural ventilation system cannot ensure a comfortable internal working climate. It is well suited for retrofit into existing natural ventilation systems to boost the cooling effect. The natural ventilation system is supported by the cooler inlet air, so that with the same free inlet area a lower room temperature can be achieved.


CoolStream N is mounted into the façade of a building. A conventional weather louvre system is fitted onto the outside of the unit. It is only 425mm in depth, allowing installation into most kinds of buildings. 

Modular design - flexibility in design and installation

Its modular design and high degree of pre-assembly facilitate installation. The modular system is available in 400 mm increments and up to 10 metres wide. It has four different heights between 666 mm and 2000 mm. Its largest standard geometric size is 20 m2. With only 425mm overall depth and a wide variety of available paint finishes, the CoolStream N can be installed into most kinds of buildings. Click here for the product specification.

Fan supported

If the conditions make it difficult to run a natural cooling system, CoolStream N units can be optionally equipped with high efficiency EC fans which provide the air flow the room needs. They operate independently from the conditions outside and operating at full variable speed, providing just the right amount of airflow.

Safe and environmentally friendly

If additional airflow is required, as an option CoolStream N is designed to ensure that water circulates safely, at the correct temperature. The process water is refreshed to avoid the growth of bacteria. The design prevents the incidence of sunlight and protects the desorption medium from the external environment. All this results in optimum water quality.

CoolStream N units have the highest degree of hygiene, with an integrated water quality control system and hygiene certificate to VDI 6022. CoolStream N units run only on water and require no CFC or similar refrigerants.

Energy and water efficient

CoolStream N units consume only around only around 50 litres of water per 10,000m³/h of supplied air, and use virtually no electric power.

Cooling tailored to the building

Colt can advise on all aspects of the ventilation design. With the help of the most advanced CFD calculations, Colt can provide support right at the start of the project and thereby provide definitive information as regards the expected performance and conditions within the conditioned space.

Limitations of application

CoolStream needs a suitable environment for it to be able to perform correctly.

It should not:

  • Be allowed to draw in air which is unusually humid or containing unusual amounts of particulates.
  • Operate with rain water, distilled and demineralised water or with contaminated drinking water.
  • Be used for the cooling of smaller spaces, spaces without the provision of exhaust air or spaces either with significant over- or under-pressure.
  • Be used in a space in which a low humidity is needed or where there are corrosive gases.
  • Be used for the direct cooling of machines and processes which need an absolutely constant temperature and therefore constant cooling power independent of the ambient conditions, since the cooling power of is higher in the summer than in the winter, and this depends on the weather.

Consult with Colt for further information.

Related Information

Evaporative cooling systems

Evaporative cooling systems

Find out more about how evaporative cooling systems can reduce your energy costs...

The Colt climate control product range

The Colt climate control product range

Find out about the natural and powered ventilators which work with CoolStream...

Colt Projects

Colt projects

Read about our projects in the United Kingdom and around the world...