Researchers at Germany’s Fraunhofer Institute for Wood Research, however, have developed a reportedly greener alternative that they claim works just as well – it’s foam made from wood.

To produce the foam, wood particles are first ground so small that they form into a slimy solution. A gas is then added to that slime, causing it to take on a frothy consistency. Once that froth hardens – a process that is “aided by natural substances contained in the wood” – a dry, porous foam is the result. The finished product can take the form of either rigid foam boards, or flexible mats.

Wood foam may be a new form of green home insulation.