Cork is a fantastic, 100% natural, material that has been used as an insulting material for years, although is not well known by most of the people working on sustainable and zero carbon projects.

So what makes this material special?

Cork is the bark of Cork Oak (Quercus Suber), collected every 9 years and later transformed and adapted to different uses. During its life, cork retains an elevated portion of CO2 and requires very low energy to be transformed.

Cork insulation

The most common use in construction – as a thermal insulation material – is Insulation Cork Board (ICB). This material is produced using raw cork (which can be a sub product of the cork stopper industry) in granulated form that is placed in autoclave where it stays for 20 minutes under vapor at 360º C (680º F). As the cork starts to expand and forms into blocks, it starts to agglutinate by means of its natural resin and also gains its characteristic brown color. The process is free of any artificial chemicals keeping the material 100% natural.

Cork is particularly resistant to insects and maintains its characteristics over time. In 2000, in the north of Portugal, a very large cold store built in 1969 was dismantled. Cork was used as thermal insulation and it was fully recovered to produce new cork based materials. What is remarkable is that the cork was analyzed in laboratory and had exactly the same characteristics as new cork meaning that its use hasn’t diminished any of its qualities.

In a recently completed K-12 school renovation project where we used cork extensively as a thermal insulation material on roofs (metal and concrete slab), we came to the following conclusions:

• The material behaves very well during construction, in good or bad weather;

• No special skill is necessary to apply this material;

• Any cuts or changes needed during work are easily achieved on site.

In an ongoing project we’re using the same material as a roof and facade insulation as part of a render system and expect to achieve a very high performance for the building.

In recent years, Portuguese architects have been exploring this material as a cladding. The Portuguese pavilion in the Hanover Expo 2000 used cork blocks as a facade. Recently, the Portuguese Pavilion in the Expo Shanghai which was entirely covered in cork panels won a design award and also in Architectos Anonimos ‘s Cork House which is shown below.

Coimbra, Portugal - Pavilhão de Portugal Expo 2000, Álvaro Siza & Eduardo Souto de Moura.

As a conclusion, we can say that cork is a natural, recyclable and environmental friendly product, highly adequate for green or zero carbon projects, as insulation and cladding material, with a guaranty of total reuse in the end of the building life-cycle making it a very good cradle-to-cradle material.

Cork House by Arquitectos Anonimos, Portugal.

For more information from a cork supplier, see Amorim Cork Composites.

Fernando Ribeiro studied in Portugal and England where he obtained a Master Degree in Architectural Design after which he worked in Macau on several high profile projects. He is the co-founder of Arqwork Arquitectura, a practice engaged in a broad range of projects from K-12 schools to retail spaces.  His practice is driven by passion in designing buildings and enhancing people’s lives. Fernando’s interest in sustainable design led him to engage in developing a more practical approach to architecture through the use of simple technical solutions and natural materials.