Overview

Owner: City of Seattle

Architect: Bassetti Architects & Bohlin Cywinski Jackson

Builder: Hoffman Construction

Location: Seattle, WA

Building type(s): municipal offices, public spaces, council chambers

Size: 198,000 SF

Project scope: one building, part of planned civic center area

Completion date: July 2003

Rating: LEED gold

Seattle City Hall is located in the heart of the master-planned Civic Center, downtown Seattle, Washington. Encompassing nearly 200,000 square feet, the building hosts both interior and exterior public gathering spaces, council offices, mayoral suite, council chambers and public reception areas. City Hall is situated in close proximity to public transit, within easy walking distance of a variety of services, and provides bicycle storage and showers for 320 full-time occupants. Based on the City’s Sustainable Building Policy which requires a minimum Silver LEED rating, Seattle City Hall has been awarded a LEED Gold certification by the US Green Building Council.

FOR MORE INFORMATION:
http://www.betterbricks.com/default.aspx?
pid=casestudy&casestudyid=17&sectionname=overview
BETTERBRICKS
www.betterbricks.com
888.216.5357
BASSETTI ARCHITECTS
www.bassettiarch.com
Greg Hepp AIA, Principal
206.340.9500
CITY OF SEATTLE
www.cityofseattle.net/sustainablebuilding
Photo: Eric Stuhaug

ENVIRONMENTAL ASPECTS

Environmental features of Seattle City Hall include a green roof, rainwater cistern, high efficiency mechanical systems, daylighting, underfloor air distribution, demand controlled ventilation, water conservation, and use of recycled materials.

Low-flow plumbing fixtures and waterless urinals reduce the demand for potable water. High efficiency drip irrigation provides landscape needs. A rainwater collection cistern stores up to 30,000 cubic feet of rainwater from the roof and adjacent plaza, to be used for toilet flushing and landscape irrigation. The lobby roof is planted with a green roof to reduce rainwater runoff into the stormwater system, while also adding insulation and reducing heat absorption.

High efficiency water chillers, variable speed fans and pumps and demand control ventilation were installed. Direct-drive, permanent magnet elevator motors reduce the electrical demand. Commissioning was performed on the building systems to insure they perform interactively according to operational requirements.

High efficiency lighting paired with daylighting provides illumination when and where it is needed while enhancing the quality of work and meeting spaces. Photosensors control indirect, efficient T5 fixtures through dimming ballasts, saving energy. To minimize unwanted heat gain and optimize energy performance, low-emissivity glazing, integral ceramic frit stripe shading, light shelves, and overhead shading are combined to correspond to the unique needs of each side of the building.

A raised floor in the northern office tower is used to supply air closer to occupants and to allow for warmer supply air than typical ceiling mounted diffusers. This strategy significantly increases the number of hours per year that outside air can be used as the primary cooling source. Low toxic adhesives, sealants, paints and coatings were used throughout the building. Demand control ventilation provides constant monitoring of the quality of the indoor air, adjusting to predetermined quality levels as needed.