WWU has embraced ambitious sustainability plans and is committed to creating a showcase of sustainable design. Sustainability goals include pursuit of Net Zero Energy and reduction of embodied carbon, and the project team is exploring options to achieve portions of the Living Building Challenge. A large rooftop PV array will help meet energy needs.
Sustainability is a top priority for structural engineering, too. The university team was intent on using mass timber, but were apprehensive about how the material would be implemented in a lab building and whether it would fit the project budget. To facilitate decision-making, Coughlin Porter Lundeen provided embodied carbon metrics that quantified the carbon savings captured with a mass timber system, including how it compares to a conventional non-timber system. This measurable value gave stakeholders confidence that this was the right decision. The current design fits both performance and budget, and utilizes cross-laminated timber (CLT) floor and roof panels supported by glulam timber columns and beams.
Working closely with Perkins&Will, we defined a construction type that would allow for an unrated timber structural system, resulting in thinner floor panels, smaller framing members, and simpler connections. This meant encouraging the team to rethink a traditional mechanical layout and avoid a penthouse mechanical level, as well as developing a fire code strategy that incorporated the adjacent existing building. Relocating heavy mechanical equipment below grade also eliminated the need for soil improvements.
Leveraging our experience with research spaces and labs was crucial, especially when designing a structural layout that supported necessary floor vibration performance. We worked with WWU to communicate true floor vibration needs (rather than relying on default lab criteria) and choose strategic locations for sensitive lab equipment. Ultimately, relaxed floor vibration requirements for the building enabled a system that’s customized, efficient, economical, and a great fit for Western’s needs.
Similar to other projects on campus, the building is located over the Chuckanut Bedrock Formation, with softer soils between the foundations and the bedrock. To support the building, ground improvement consisting of aggregate piers or stone columns will be used to transfer loads from the foundations into the bedrock below.
Challenged to reduce carbon footprint wherever possible, we’re questioning basic assumptions about building structure: Is concrete topping system necessary to achieve the structural, architectural, and acoustic goals? Are there alternatives that could reduce the amount of cement? Would these reductions, and the reduced weight, yield savings for structural systems?
We are exploring alternative floor assemblies (including utilizing CLT panels as the seismic diaphragm, a method not currently allowed under the building code, but one that we’ve successfully implemented through a code-alternate approach). Along the way, we are providing real-time metrics related to embodied carbon so that it is always factored into decision-making.
Ever wonder what happens at a mass timber manufacturing plant? The team toured the Kalesnikoff plant and learned about their responsible approach to quality in both product and process.
Images © Francis Zera Photography