If you have visited the new Apple store in Brussels then you would have seen first-hand the striking façades coated with white clay. Natural lime and clay based plasters are an increasingly popular choice among architects and homeowners due to their aesthetic appeal and sustainable credentials - clay plaster requires just 10% of the energy input of gypsum plaster and has 10 times lower embodied CO2.
On top of this, these materials are also known to improve the indoor climate of a building by helping to maintain a steady temperature and humidity level – important factors for occupant comfort. However, a lack of understanding and evidence has limited recognition of these effects within the construction industry.
In order to address this, producers BCB and Claytec teamed up with researchers from the University of Bath within the ECO-SEE project. By studying the characteristics of the plasters, together they were able to develop new mixtures, optimised to improve the indoor environment. The researchers found that, by adding plant based aggregates such as straw and hemp, the thermal conductivity and moisture buffering potential of the plasters could be greatly increased. The introduction of these additives increases the capacity of the plasters to adsorb and desorb water vapour. It also reduces the density, which improves thermal insulation properties.