Building walls that can store carbon

A Canadian startup is using waste wood to create carbon-negative building walls

Spotted: There is a growing movement around the world to help people better insulate their homes. A properly insulated home not only reduces heating and cooling expenditure – it also makes homes more comfortable. Now, a Canadian startup called Calmura Natural Walls is going even further, with a carbon-negative circular wall system.

Calmura’s system is designed around panels made from chipped waste wood cast with a lime and clay binder, and an insulating foam infill that is added on-site. The result is a ‘monolithic building envelope’ which can be used around standard wood framing.

The 600 mm x 1200 mm panels come in two types. An Interior Finishing Board is thinner and denser, for easier cutting-in of plumbing and electrics. A lighter, thicker, Exterior Insulation Panel provides better thermal protection on the outside of wood framing. These panels can also be used in building retrofits, along with mass timber elements, and in floors to provide thermal and sound insulation, as well as a fire separation layer.

Calmura’s biocomposite walls offer homeowners several immediate benefits, such as protection from fire, mould, pests, and earthquakes. They also ensure a stable temperature, reducing the owner’s energy bills while ensuring a comfortable home environment.

In addition to the cost-saving and comfort benefits, the startup’s walls serve an even greater environmental purpose by storing carbon. The wood waste that is used to make the wall panels would normally be burned, composted, or sent to landfill, leading to emissions of greenhouse gases. Instead, carbon is locked away for the long term.

Cities are increasingly looking at implementing policies for zero-carbon footprint buildings. But meeting zero-carbon targets will also mean retrofitting existing buildings. The market for this is just beginning to grow, but already we are seeing a number of exciting innovations in this space. In addition to Calmura, these include a German company retrofitting existing buildings with a second skin and a platform that finds green solutions for commercial buildings.