.Air Engineering Fields

Comfort Air Conditioning:

Cool Ceiling : KARO

The Cool Ceiling technology with KARO has been refined and successfully utilized in Europe for over 15 years.

The principle is to create a cool or warm ceiling surface in order to condition a room by the most natural way: Radiation.

In buildings of office space, executive floors, architecture cabinets and all offices where people remain seated most of the time, the degree of comfort to be achieved is critical and directly linked to the people productivity.

Studies have proven that working in a quiet and comfortable atmosphere without draft increase the productivity of the people up to 50% and even more if we compare to simpler systems, enhance the creativity and the imagination.

With the conventional systems in summer, blast of cold air will cool down the human body and the room walls with high air volumes displacements. In our case, the cold ceiling surface will directly cool down the different heat sources in the room by radiations. A small ventilation is foreseen in addition to bring the necessary fresh air for hygienic and dehumidification purpose.

As a result, human body heat is naturally dissipated, no big air volumes are involved, no draft, lesser risk of disease, comfort in enhanced and so, productivity is improved. In addition to the comfort improvements, the KARO Cool Ceiling has a deep impact on energy savings and floor-to-floor height reduction in terms of building construction. Consequently, the solution is the most economic in terms of investment costs. A theoretical study as well as a direct application in a Mock-up office in Hong-Kong can be downloaded from the website, showing concretely those issues.


Water circulates in thin capillary tubes, the KARO Mats, or copper pipes, which are installed in the room ceiling.

Those Mats create a cool or warm surface and so, condition the air using a natural principle: radiation (cooling emission about 80 W/m2, heating emission about 90 W/m2).

In Europe, heating by the ceiling is now a common practice and since 15 years, cooling is also well developed, but very seldom used in other countries.


  • Thermal comfort enhancement:
    Comfort levels are better than those of other A/C systems because radiant loads are treated directly and air motion in the space is at low ventilation levels.
  • Noise reduction:
    The air volumes’ requirements do not exceed those required for ventilation and dehumidification. So the noise created by the fans is reduced accordingly.
  • Space savings:
    In existing buildings, where ceiling heights and plenum space are important issues, the KARO Cool Ceiling allows space between the false ceiling and the floor slab to be minimized, and ceiling heights to be raised to the architects’ pleasure levels.

    When used in new constructions, the building owners can save investment costs by decreasing the overall height of the building, or adding about one floor for every 6 floors when compared to conventional constructions.
  • Energy savings:
    In conventional A/C systems, as a quick energy analysis, we can already emphasize that we need to blow big air volume at 14 C to cool down a room with air only. To produce air at 14 C, we need water at 7 C. So, with an outside air at 35 C, the temperature difference between the outside air and the cold water is 28 C.

    For the KARO system, if we maintain the ceiling surface at 15 C, we achieve the same cooling, but we reduce the temperature difference from 28 to 20 C, meaning a saving of 35% of the energy requirement for the same cooling effect!

References in Europe:

Country Project Active Area Installation Picture
Switzerland Edipresse 5,900 m2 2001 NA
Belgium Glaverbel Building 12,000 m2 1997 NA
France Nestle France 21,000 m2 1994 NA

References in Asia:

  • Mock-up Office in Hong-Kong – 60 m2 (2005)
    KARO Cool Ceiling System installed in an existing architecture office in Hong-Kong (Aberdeen), replacing the fan coil units system.
    A thermography was done to measure the performances of the ceiling.

    Download Hong-Kong Mock-up analysis.pdf
  • GOURMET Supermarket in Macau – 720 m2 (2005)
    The installation is under process, it will be finished beginning of 2006.

Illustration n°1

Illustration n°2

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