Every building has a lifespan determined by its materials, purpose, and location. At the end of the building’s usefulness, or if the site is more valuable for another purpose, it will be replaced. Urban explorers may revere ruin porn, but the materials and assemblies may have a life beyond abandonment.
The extraction, manufacture, transportation, assembly, maintenance, and disposal of the materials of a building make up the embodied carbon, or CO2 equivalent, that went into the construction and ultimate demolition of a structure. Operational carbon is its companion, encompassing the carbon used in the power, heating, cooling, water and waste streams. Together, these make up the building lifecycle carbon. As we build increasingly energy-efficient buildings, the proportion of a building’s lifecycle carbon that comes from embodied carbon becomes more significant, and therefore, more important to address. We can do this in four ways:
- Lean Design. More efficient design to optimize building use reduces embodied carbon and construction cost. Buckminster Fuller stated, “Our beds are empty two-thirds of the time. Our living rooms are empty seven-eighths of the time. Our office buildings are empty one-half of the time. It’s time we gave this some thought.” Building right-sized and flexible spaces can extend their period of utility.
- Durable, honest materials. More efficient use of materials includes choosing to do without redundant finishes (carpet on top of wood), and using materials with durability to match the expected life of the building. These reduce the capital investment for repair and replacement costs.
- Local sources. More efficient materials reduce the embodied carbon in transportation by using locally harvested materials and locally manufactured assemblies. Transportation costs are volatile, with a direct impact on construction costs. The closer the source, the less cost and carbon.
- Simplify. Streamlining the construction process is important because labour costs have a direct relationship with construction costs, often comprising 50-70% of the value. Those hours are accompanied by embodied carbon in the power consumed in the assembly of the building, and the transport of workers to the site.
unabridged Architecture identifies the most cost-effective opportunities to reduce embodied carbon associated with a project, through lean design and construction, reclaimed and regional materials, recovering waste, or using materials with lower carbon over the lifetime of the project. We also consider methods of deconstruction at the end of a building’s life in order to recover those materials and their embodied carbon. We endeavor to design buildings that will remain beloved and contribute to the city, but when they no longer serve their purpose, they should feed the cradle-to-cradle cycle for buildings, and find a second life.