Embodied carbon footprint can be reduced by using conventional materials

Builders for Climate Action have found that embodied carbon accounted for an outsized portion of greenhouse gas emissions for new low-rise construction.

A new white paper from the group says that the carbon footprint can be significantly reduced by using conventional materials. The highest embodied carbon came from a building with high-Portland-cement concrete, and extruded polystyrene and spray-foam insulation. A typical model included concrete with some supplemental cementitious materials (SCMs), along with mineral wool insulation.

A lower-carbon alternative, called a “drawdown building” incorporated high-SCM concrete, and cellulose and wood fiber insulation. The carbon-storing model included:

· Insulated concrete forms with high-SCM concrete

· Expanded glass sub-grade insulation

· Straw and wood fiberboard insulation

· Wood cladding

· Compressed straw panel interior walls

· ReWall interior finishes

· Wood windows

· Linoleum and Forest Stewardship Council-certified softwood flooring

· Cedar shake roofing

An energy-efficient drawdown building located in Toronto and using renewable grid electricity would avoid 614 metric tons of carbon emissions over 30 years, according to the report. One caveat: Drawdown buildings rely heavily on wood products, and there are emerging questions about whether wood is universally a carbon-storing material.