Rainier Square

Seattle, WA

A major redevelopment of a city block in Seattle’s urban core


  • Electrochromic glass
  • Building-wide heat recovery 
  • Central condenser water loop
  • Winner: ASCE (American Society of Civil Engineers) 2022 Outstanding Civil Engineering Achievement Award
  • Winner: ACEC 2022 Engineering Excellence Award
  • Finalist: ACEC 2022 Engineering Excellence Awards, Gold Award structural systems

The Rainier Square project is a major redevelopment of a city block in Seattle’s urban core. The project consists of a 60-story office/residential tower and a 9-story office over one story of retail and an underground parking garage. During schematic design, OB360 created models to evaluate 11 different HVAC system combinations for compliance with the 2012 Seattle Energy Code Total Building Performance (C407) and LEED-CS 2009/v4 performance criteria. Throughout the design phase, OB360 also investigated other measures to reduce building HVAC loads, including electrochromic glass and building wide heat recovery via a central condenser water loop. Scope included coordinating a pre-submittal conference with Seattle Department of Constructions and Inspections (SDCI), as well completing the LEED 2009 Core and Shell energy model submissions to GBCI for the high-rise office/residential tower and LEED v4 Core and Shell energy model submissions for the mid-rise office building. In this case, the LEED Pilot Credit 95 was used to demonstrate EAc1 credits given its use of low-carbon Seattle City Light electricity to power residential and office water source heat pumps.