August 20, 2019
Office Incorporates Material Never Before Used in Sacramento for a Building’s Structure
In an area famed for its fertile farmland, a new type of green initiative has been taking root as DPR Construction puts the finishing touches on its innovative new office space at 1801 J Street in Sacramento. When DPR opens a new office, it aims to forge a new path for sustainability, creating “living labs” to show what is possible in green and healthy workplace design. In Sacramento, DPR is manifesting that by incorporating a material never before used for a building’s structure in the city: mass timber with cross-laminated timber (CLT) panels. A renewable resource, mass timber can be an integral part of a low-carbon development; for this project, it was vital to DPR meeting its goals for sustainable design, as well as achieving LEED® Platinum and WELLTM certification standards.
In a move that itself demonstrates the “reduce, reuse and recycle” mantra of conservation, DPR purchased an existing property for re-use, utilizing a design by SmithGroup to transform it into DPR’s new Sacramento home. The existing 28,833-sq.-ft. midtown property’s two buildings are targeting Zero Energy Certification (ZNE) from the International Living Future Institute. To achieve ZNE, the office will offset its energy use via on-site photovoltaic solar energy generation and ban the use of any combustibles, relying on electrical energy alone. Key to DPR’s ability to meet sustainable design goals for this project was the incorporation of mass timber construction with cross-laminated timber panels made up of pressed, dried timber boards stacked at right angles and glued together with non-toxic adhesive—a material not previously used in this manner in Sacramento.
Mass timber products are engineered for loads similar in strength to structural materials like concrete and steel, but they allow crews to build tall, with a lighter, natural, low-carbon and high-quality material. This effort sheds light on the possibilities for the region’s aging building stock, and it showcases how incorporating wood in an exciting, sustainable manner can benefit commercial projects.
Wood Elements Deliver Strength, Resiliency While Reducing Carbon Footprint
From a structural perspective, CLT and mass timber elements provide high-strength, resilient systems capable of long spans and significant wind and seismic force resistance. At the time of design review, Sacramento building codes did not yet recognize these systems for use as lateral force-resisting elements, so design teams reached beyond existing codes to demonstrate equivalent or superior performance with CLT. They made use of the many years of research and testing conducted by organizations such as WoodWorks, FP Innovations, ANSI/APA and Structurlam to navigate code, design and construction issues. It is also the first multi-story shear wall application of CLT in the State of California.
From a sustainability perspective, mass timber offers even more benefit. Because of its use in this structure, the embodied carbon is estimated to be lower by 170 metric tons than comparable structures using traditional materials. Further, it is estimated that US & Canadian forests grow enough wood for this project in only 12 seconds, highlighting the current availability of wood product. And it’s not just the timber; the building utilizes mechanical, electrical and plumbing systems to reduce energy use vs. baseline by 45%, with 424 photovoltaic panels for an annual production of 265,178 kWh/year. In the sunny Central Valley, this is projected to yield 107% of onsite energy needs annually. A 9.8 kWh battery backup system is included for added resiliency during system outages and to serve as a community hub in the event of natural disaster.
Exposed Timber Provides Unique Connection to Nature
Exposed timber also provided DPR with the opportunity to create a high-end, modern office environment that showcases not only its skill but also its environmental stewardship. Wood elements also accomplish something other building materials cannot—they have the unique ability to connect people to the natural environment. This unique combination of attributes provided advantages not offered by other building systems. The challenge was to make full use of these benefits in a manner most compatible with the existing concrete and masonry structure. It is here that CLT framing became the clear choice.
Mass timber also means the application of interior finish materials is unnecessary, helping to limit the amount of toxic materials present. Exposed wood also brings nature into the space by creating a tactile experience and a healthy indoor air quality. The sense of biophilia, the connections humans subconsciously seek with the rest of life, is reinforced by Solatubes® on the roof to diffuse light and bring in anti-glare, natural light, operable windows that highlight the local microclimate’s Delta Breeze, and material finishes with familiar patterns and textures, such as wood, stone, hexagons, bubbles and wool. The second story terrace engages with the community in the “City of Trees” that is Sacramento, and can be accessed through a new communicating stair from Level 1 to Level 2. The stair uses a CLT landing and old growth Douglas Fir treads and risers.
The unusual application of mass timber in this project pushed the boundaries of what is possible with the material and challenged the entire design and consultant teams. When considering the massing, the perception of the structure in three dimensions, the design concept called for the placement of a distinct pavilion atop the historic building to help define the exterior shape. The use of mass timber as a way to distinguish the pavilion addition from the rest of the existing building created a recognizable stark contrast consistent with the design scheme.
A Continued Commitment to Sustainable Design
DPR has long been committed to green building and sustainable design, and this project further demonstrates this. Originally constructed in 1940 and renovated in 1993, this adaptive re-use will house the DPR office, with open office seating areas, an active/addressable seating plan, meeting rooms, break rooms, open collaborative areas, focus areas, a training room, lounge spaces and other special use spaces. This design allows DPR to provide leasing opportunities on the ground level, a move that will not only activate J Street but will also connect DPR to the community at large. While the west building is a two-story structure that received extensive interior and exterior improvements, the single-story east building received a full second story addition constructed entirely of mass timber.
As an active member of the US Green Building Council since 1999, DPR has constructed green/LEED™-certified projects for various customers across the nation. In 2003, DPR completed construction of its 52,300-sq.-ft., high-performance office building in Sacramento, a ground-up facility that was designated the first privately owned LEED™ project in the Central Valley.