Aerial view of the Washington State Convention Center; Aerial view of the Washington State Convention Center;

Washington State Convention Center Addition, Seattle, WA

Washington State Convention Center addition to breathe new life into Seattle’s urban core

At 1.4-millionft2 and $1.6bn, the Washington State Convention Center (WSCC) expansion project is the single largest construction effort in Seattle history. Working in collaboration with Seattle’s LMN Architects, the addition will double WSCC’s current capacity and introduce a new 30-story residential tower and 16-story office building, along with a number of public spaces. Developer Pine Street Group estimates that the new expansion will generate as many as 2,300 new jobs and bring the city an additional $200m in visitor spending. Located in the heart of downtown, the WSCC addition will transform several under-utilised blocks into a thriving mixed-use district and improve connections between Capitol Hill and the waterfront.

Arup is performing mechanical, electrical and plumbing engineering and fire/code consulting for the WSCC addition, which is set to start construction in the latter part of 2018. The new facility is scheduled to open in 2021.

Maximising sustainability and cost savings without compromising design

The WSCC expansion is intended to achieve new national benchmarks in convention center sustainability. To help the project meet these goals, our MEP experts worked closely with the design team to develop systems that redefine performance standards.

Project Summary


$1.6bn project cost

2,300projected new jobs created

$200mprojected visitor spending

Strategic MEP solutions

The original convention center’s “open concept” pre-function areas are challenging to heat and cool and have spurred complaints from visitors, particularly during the winter. The new addition’s lobby and circulation area call for even greater vertical stacking and connectivity. To ensure that the space achieves the required comfort level while reducing energy use, we designed a hybrid heating and cooling solution that combines the benefits of variable air volume (VAV) and radiant floor heating and cooling. In addition to being more sustainable than an industry-standard approach, this solution enabled the design team to maximise ceiling heights and cut floor-to-floor heights, reducing mechanical construction costs by $1m.

Supporting safety and design

Our fire and life safety experts brought more value to the project by developing a performance-based fire engineering strategy that reduced smoke exhaust and makeup air by more than 1m cfm, enabling the architect to achieve the desired space usage and interconnectivity goals. The performance-based design developed reduced exit widths using modeled egress timing and computational fluid dynamics fire simulations. The team worked closely with the Seattle Fire Department and Seattle Department of Construction and Inspection to ensure all life safety and fire-fighting needs were met while allowing over 200ft of vertical connectivity from the below grade exhibit hall to the ballroom level at the top of the building.

View of Washington State Convention Center from Boren Avenue View of Washington State Convention Center from Boren Avenue

Streamlining code compliance

Recent changes in Seattle’s envelope systems requirements meant that early code studies were crucial to achieving compliance. The Arup team evaluated multiple approaches in the early phases of design, using Rhino and Grasshopper. We also created custom tools to generate building performance models that leveraged the benefits of Rhino and EneryPlus. This approach aided the client in efficiently vetting various mechanical and architectural design options, and helped to identify the path with the lowest cost and least risk.

BIM: Improving efficiency and collaboration

To accelerate coordination and enhance constructability early in the design process, the Contractor’s BIM detailers worked alongside Arup staff in our offices to co-create a detailed BIM model for the project. This approach allowed the construction team to provide critical constructability input–of particular importance when single duct fittings can weigh 20,000lbs.