1 De Haro

1 De Haro is a 170,000-sf, four-story office building in San Francisco’s Design District and is comprised of three levels of mass timber construction (cross laminated timber [CLT] and glulam framing]) over one level of concrete. While its upper three levels are for office usage, the ground-level concrete podium is for light industrial work. The milestone project holds multiple titles, including the CLT building in the City of San Francisco and the first multi-story mass timber building in California. The structure was topped out in February 2020 and the building was ready for occupancy in Summer 2021.

Mass Timber and Concrete Focus​

With site soils, the project team needed to reduce the weight of the structure, so explored the option of mass timber. Mass timber also provided a sustainable component to the project as it equates to roughly 2,000-metric tons of stored carbon. While the concrete component of 1 De Haro was a factor in weight, the team was able to approach its usage with sustainability standards, performing a retroactive Life-Cycle Analysis.

LCA Measurements

DCI performed a retroactive Life-Cycle Analysis (LCA) on 1 De Haro. During procurement, DCI received two different sets of concrete mix submittals for the cast-in-place concrete portion of the building: one mid-grade set with 15-30% cement replacement and one high-grade set with 70% cement replacement in the foundations, plus 20-50% for all other applications. All high-grade mixes also contained the carbon injection admixture, CarbonCure. When compared to the NRMCA Pacific Southwest Baseline, the cradle-to-gate GWP of the entire structure was reduced by 5% with the mid-grade concrete mixes and 20% with the high-grade concrete mixes.

DCI found that the foundation elements provided the biggest opportunity for embodied carbon reduction. The global warming potential associated with the high-grade foundation mixtures was nearly half of the mid-grade and NRMCA Pacific Southwest Baseline mixtures.