If we are to successfully reverse the effects of climate change, then we must thoughtfully construct buildings that soak up carbon dioxide rather than produce it. But in order for that to happen, the building trade needs to redirect its focus.
So much of the focus of “green buildings” is on energy efficiency — triple-pane, gas-infused windows that lock in heat or closed-cell spray foam insulation. These technologies are designed to reduce the need for heating and cooling and therefore reduce greenhouse gas emissions, like carbon dioxide. But Chris Magwood, director of The Endeavour Centre Sustainable Building School, says that building such a structure might actually contribute more greenhouse gasses than raising a basic building.
What is embodied carbon?
It all boils down to “embodied carbon” — carbon embedded in the materials used in construction. Embodied carbon is different from the carbon dioxide released during the operational phase, the period after construction when people move in and use the building. So, a structure made with say, XPS and closed-cell foam insulation, carpet, and vinyl windows may be the most energy-efficient during the operational phase, but taking into account the materials and it becomes a significant source of carbon emissions.
In one of his studies Magwood, who built his own straw bale home, suggests opting instead for sustainable building materials like straw and wood fiberboard insulation, softwood floors, and wood windows. Having an overall aim of zero net carbon emissions for green buildings — from materials harvest and manufacturing, to the energy needs of the structure — is just a starting point.
Pulling CO2 out of the air
Magwood shows how buildings can actually pull carbon dioxide from the atmosphere. The building sector is one of the biggest contributors to climate change — contributing nearly 39 percent of global energy use and energy-related carbon dioxide emissions. Embodied carbon is responsible for 11 percent of total greenhouse gas emissions. But using materials that store carbon, like straw, wood, linoleum, and cedar, can actually soak up carbon dioxide from the atmosphere and store it in the building’s walls. It may seem counterintuitive, but just through careful selection of materials, the building sector could transform from a major carbon emitter to a carbon sink.
When buildings are designed to be a carbon sink, it is possible to make a zero-net carbon structure. And — even better — carbon-storing buildings that are powered by renewable energy can actually reverse climate change.