Timber! The Promise of CLT
Eight lessons learned to make the most of mass timber buildings
JONES UP CLOSE
EXECUTIVE SUMMARY
Ten years ago, there were no Cross Laminated Timber (CLT) factories in the United States. Today, there are more than a dozen. The speed with which this renewable material has been taken up in an industry that is notoriously slow to change speaks to its promise: it is a strong, safe, beautiful, and low-carbon alternative (or complement) to concrete and steel —and its use also speeds construction.
CLT is still a relatively new material for building in New England, but it won’t be for long. It is suitable in just about any midrise project that involves new construction, including additions and renovations.
Anyone who works in the AEC industry is well aware of our sector’s contribution to greenhouse gas emissions; taken together, buildings (operation) and their construction account for 38% of all energy-related CO2, according to the UN 2020 Global Status Report for Building and Construction.
More and more facilities in Massachusetts are being planned and built using CLT each day. Jones recently designed – and learned a lot along the way – one of our state’s first CLT buildings, the $28.1 million (TPC) C. Gerald Lucey office building in Brockton. This building, with a CLT and glulam beam and column structural system surrounding a steel core, is the Commonwealth’s first CLT building of this scale to use solely public funds.
LESSONS LEARNED
For any owner or developer looking to reduce their carbon footprint and construction time while capitalizing on the material’s inspiring design, health and wellness possibilities, CLT deserves serious consideration. Here’s what you need to know before you press go.
Buy-in starts at the top
Mass timber presents new design opportunities — and challenges
Coordination is key
Anticipate capital costs coming down as demand increases
REVITALIZING AT DIFFERENT SCALES
Early participation of supplier and installer required
Acoustic considerations are considerable
Some designs may still require variances
There are so many good reasons to use wood
Yes. The whole calculation of embodied energy and sequestration relative to mass timber — which some scientists question — depends on preserving old growth forests and responsible forest management. It is critical that designers specify only salvaged wood or wood certified by the Forest Stewardship Council (FSC) in mass timber projects. This means the products come from forests that are managed to reduce habitat destruction and optimize growing period, then sustainably harvested and replanted as part of a larger strategy of carbon sequestration.
The most important aspect of sustainability in terms of mass timber is its embodied energy. According to Wood for Good, an organization that advocates for sustainable wood construction, concrete requires five times the amount of energy to go from raw material to finished product, while steel requires 24 times the amount of energy. Then there’s the fact that wood sequesters carbon, unlike its concrete and steel counterparts, which introduce more carbon into the atmosphere. And, because wood is a good insulator, less energy is needed to heat and cool wood buildings. Wood also has tremendous visual appeal; its warmth and beauty has a comforting and uplifting effect on people.
Take a look at these stats for the C. Gerald Lucey Building:
• Volume of wood products used: 333 cubic meters (11,763 cubic feet)
• According to the Woodworks Calculator, U.S. and Canadian forests grow this much wood in: 1 minute
• Total potential carbon benefit: 362 metric tons
• Carbon stored in the wood: 261 Metric Tons.
• Avoided greenhouse gas emissions: 101 Metric Tons.