A recent study shows that green walls can reduce heat loss from buildings by about 30%. In other words, they could be effective thermal insulators that could help reduce heating requirements.
This field study, conducted by researchers at the UK's University of Plymouth, focused on a pre-1970s building (the University's Sustainability Hub) and compared the heat-trapping capabilities of a conventional concrete and brick wall with those of a green wall. The living wall was developed from a system of flexible felt sheets with pockets into which soil and plants were added.