High Performing Buildings - Spring 2008 - (Page 13) In the lobby, steel columns establish a civic ambiance and human scale. The natural colors of the materials form the palette. shades glazing from slab to slab. The vertical frit responds to the linear movement along the corridor by changing the focus of the view as one moves along its length. Frit also sets apart areas of curtain wall to break down the building’s mass and solidity and reinforce its crisp planar quality. In all, 15 glass types optimized performance and refined the building envelope. Bohlin Cywinski Jackson worked closely with the glazing subcontractor to develop the building’s curtain wall within a fixed budget. The design-build process used shop drawings to adapt details to optimize the curtain wall components. A standard stick system was selected as most cost effective for the tower’s small size. To achieve the layered articulation of each face, custom extrusions were attached to standard curtain wall sections. This modular approach helped control cost and achieve envisioned design features. Sun shading and daylighting tools improve building performance. In the lobby, milled wood louvers on the interior of south- and west-facing window walls add visual warmth and a more human scale to the monumental space. On the tower, each face responds to its solar orientation. On the west, the horizontal exterior sunshades work in concert with lightshelves to protect workers from harsh afternoon light while reflecting and diffusing light deep into adjacent office space. The perforated aluminum plates form a horizontal counterpoint to the lobby columns, creating backdrop for the building’s main plaza and distinguishing the city hall from its taller neighbors. On the north, translucent vertical glass fins catch and reflect late afternoon light into the space. The reflection creates an illusion of depth on this flat side of the building which is animated in the changing light. The fins are a good example of the collab- S U S TA I N A B L E C H E C K L I S T From project inception, Seattle City Hall was envisioned as a progressive urban building with LEED Silver as a project requirement. Through a process of making design and sustainability choices based on merit rather than LEED points, the project surpassed this goal to achieve LEED Gold (39 points). The following are some of the most significant strategies implemented. Community Connection • Open space increased by 4.8 times, green space by 6.5 times • City offices consolidated into single campus • Minimal structured parking (only 27 spaces): building shares adjacent city garage and vehicle pool • Alternative transportation: electric vehicle charge station, bicycle storage facilities and showers • Public transit is subsidized Resource Efficiency • Rainwater harvesting and gray water system for 100% of toilet flushing and irrigation • Green roof with native and adapted plants • Waterless urinals, low flow fixtures, drip irrigation with sensors/controls • Reduced energy use: 24% below ANSI/ ASHRAE/IESNA Standard 90.1, Energy Standard for Buildings Except Low-Rise Residential Buildings, base case • High-efficiency glazing, external sunshades, thermal buffer • High-efficiency indirect lighting and daylighting controls • Solar modeling used to minimize heat loads and artificial light use • Future pathways for rooftop photovoltaic panels Occupant Well-Being • Rooftop fresh air intake with MERV-13 air filtration • Underfloor HVAC with occupant control • Low or zero VOC adhesives, sealants, and paints and carpet • Interior daylight strategies bring natural light deep into building Good Construction Practice • 88% (by weight) of construction waste recycled • 53% of construction materials manufactured regionally • 15% of construction materials with recycled content • Post-occupancy report focusing on cost analysis of sustainable design and occupant comfort Spring 2008 HIGH PERFORMING BUILDINGS 13
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