Humidity, or water steam, is the worst foe to ideal thermal insulation. Water as a main heat conductor destroys the insulation value of any material.

Water is enemy number one of any insulating system. The problem lies in water in its natural status as water steam, that is to say, humidity. Steam is a constant condition in our atmosphere and therefore it will reach by any mean through the air.

Hot air absorbs humidity

The higher the air temperature, the bigger the capacity to retain humidity. It is due to the ability of hot air to absorb steam. When air is heated it expands and makes “room” for more water molecules, so air is able to “absorb” more water (like a sponge). This process is known as “relative humidity”.

When relative humidity (RH) is zero, it can absorb all the water, but when it is 100%, it is unable to absorb even an extra drop.

“Dew point” is the temperature when the RH is of 100%. In this case, air is not able to hold water and it starts to fall, first in tiny drops known as “dew” and, afterwards, as fog (it happens when there is a sharp fall on temperatures, when there is a lot of humidity in the environment).

Temperature difference is in fact a pressure difference. Nature tends to balance this condition. Cold air is heavier than hot air. When the door of a cold room opens, cold heavy air slips from the lower part meanwhile hot air circulates through the upper part.

Hot air which contains steam comes into contact with cold surfaces and immediately it loses its ability to host humidity.

It leads to condensation: humidity is laid over the surface and insulation is exposed to its disastrous effects.

Taking into account the previous explanation, the ideal insulation would be one with the maximum gas content, air for instance, encapsulated and without the possibility of circulating.

These insulation principles have been widespread for a long time, but they have not been definitively assimilated until very recently.

The only conclusion to be reached out of these facts is that perfect insulation is to incorporate two unique characteristics:

It must incorporate the bigger amount of standstill air within the smallest room.
It must be able to tolerate water intrusion by absorption.

There is just a substance known to fulfil absolutely and truly those requirements. The material we are talking about is cork.

What is cork?

Cork is the cortex of the Mediterranean cork oak “Quercus suber”, growing in the south of Europe and the north of the African coast.
It is cultivated mainly in Portugal, Spain and Algeria.

Cork oak is a strong tree which can reach up to 20 or 25m high. Its cortex is suberized, that is to say, composed by cork, being relatively soft and spongy, very light-weighted and with deep cracks. Its cortex protects the tree from injuries, sicknesses and insects. It is a death tree part which protects the living one, most of all to survive drought (protecting internal tissues from water losses) and fires. When there is a fire, the internal cork side closes due to the heat and avoids oxygen entry and therefore combustion, protecting the tree internal parts, which enables it to regrow anew the next season.

Cork extraction is made by withdrawing cork oak cortex, where the material is located. Once cortex is withdrawn, the tree is “at rest”, and nine years later the extracting process will be renewed.

A very important part of cork industry is located in Spain (especially in Andalusia and in the south of Extremadura), where about 30 % of global production takes place.

Cork industry generates a sustainable economic activity, which does not pollute, and offers the global market a natural ecological product.