As mass timber and other high‑performance building solutions gain traction, project teams face a persistent challenge: moving from design intent and material claims to evidence‑based decisions grounded in real building performance. This hands‑on workshop uses the Double Diamond framework—Discover, Define, Develop, Deliver—as an active tool to guide attendees through understanding the challenges and solutions associated with evidence‑based design. Using Evergreen Charter School, one of the Northeast’s first mass‑timber K–12 schools, as a case study, participants will explore how developing tandem processes for evaluation and design can benefit material choices, indoor environmental quality, sustainability, and resilience in practice. While centered on educational facilities, the methods and lessons apply broadly across building types, equipping designers, contractors, and owners with practical tools to validate material strategies, inform operations, and ensure that sustainable design delivers measurable, long‑term value.