We’re all pretty familiar with common methods of cutting back on greenhouse gas emissions in our homes and offices — we know we can install better insulation, use LED lighting, and generate power using solar panels.

Those practices reduce what we in the industry call “operational carbon” — that is, the greenhouse gases that are generated from operating our buildings.

Something that you are probably less familiar with is “embodied carbon” — the greenhouse gases that are emitted when we construct those buildings. Embodied carbon is emitted when we manufacture steel, when we ship the steel, when we pour the concrete, and so on. Yes, embodied carbon contributes less than operational carbon to the enormous amount of greenhouse gas emissions associated with building construction. But, the impact of embodied carbon is growing.

The best decision we can make for reducing embodied carbon in buildings is to reuse existing buildings. Our neighborhood is already doing a great job of preserving historic structures, thereby eliminating the embodied carbon associated with replacing buildings every 30 years or so. But when we are constructing new buildings, what decisions will have the greatest impact on embodied carbon? If we look at a breakdown of what impacts embodied carbon emissions, we see the materials we select for the superstructure are a significant contributor.

Most commercial building structures are made of concrete or steel, which are both very carbon intensive materials. Wood is a lower embodied carbon alternative to these materials.

First, let me explain what we mean by “mass timber.” It’s not the same thing as boards sawn from a tree.  Mass timber is a code-approved subset of wood construction that is made up of large wood members — larger than the wood members that are typically used in residential buildings. Modern mass timber uses smaller dimensional lumber bonded together into larger components. There are a few types. Glue-laminated (glulam) elements are used for columns and beams. Cross-laminated timber (CLT) panels are often used for walls, floors, and roofs. And other variations, like nail- and dowel-laminated timber (NLT and DLT) and mass-plywood are being used and show promise.

Mass timber does more than provide environmental benefits and durable performance: It’s also beautiful! The Soto’s mass timber structural system was deliberately exposed on both the building’s exterior and interior to express the natural beauty of wood. This natural aesthetic has been proven to have a strong positive impact on human health, well-being, and productivity.

As mentioned earlier, building with mass timber results in less construction time, lower costs, and less construction noise — all important factors when building on an infill site in a dense urban neighborhood. Mass timber buildings are really lightweight when compared to conventional tall steel and concrete buildings. This allows for smaller foundations, which results in savings in both construction cost and schedule. Mass timber buildings result in shorter construction schedules because the products are prepared off-site reducing the need for material preparation and staging. This saves on not just time and labor costs, but construction noise as well. 

Eliminating the use of concrete in building roof and floor assemblies significantly shortens the construction time of mass timber buildings, since the concrete curing time is eliminated. In exposed mass timber buildings, there are also noteworthy cost savings from reduced construction assemblies (gypsum board, paint, etc.) in the exposed portions. Though material costs vary widely depending on location and timing, locally sourced timber products are not subject to tariffs, which also results in cost savings.