MS in Fire Protection Engineering
College of Engineering
Frederick Mowrer and Christopher Pascual
The Spheres, an architectural masterpiece surrounded by a high-rise building complex, is in the heart of South Lake Union in Seattle, Washington. The Spheres building pushes limitations in building design on all levels. With hexecontahedron panels tessellated over the façade of its three spherical glass glaze greenhouse globes, the design affords futuristic personality, alongside energy efficacy while sustaining life within the building. While building innovations within The Spheres are certainly notable within all disciplines of Architecture, Engineering, and Construction, the contents of this report refer to fire protection engineering and code consulting elements.
In meeting The Spheres' required fire safety objectives within the built environment, code defined structural, water-based suppression, fire alarm, and egress designs live in the building's systems. As a life safety provision, a non-combustible skeletal steel system composed of 1 to 2-hour assemblies and type IIB construction serves to protect exit through stairwells and corridors to the building's exit access and finally discharge. The water-based fire suppression and standpipe system feature a 300 psi 1000 GPM rated fire pump with an accompanying water storage tank which serves three high rises and the associated, Spheres building. In addition to the active water-based fire suppression system, an Emergency Voice/Alarm Communications System (EVACS) system protects the facility as is required because of the high-rise and atria spaces. A Very Early Smoke Detection Apparatus (VESDA) system, to account for potential stratification at the highest elevated extremities exposed to light and heat in The Spheres, is also present. Complementary to the structural fire system in place, passive egress components are present.
Finally, performance-based design using fire and egress modeling software analyzed available safe egress time (ASET) as it relates to required safe egress time (RSET). This was performed by generating a 1MW tree design fire to characterize the heat, velocity, and soot particle buildup due to fire phenomena. Tenability criteria thresholds are evaluated based on visibility to 30 ft, temperature where temperatures exceed 111.2°F, and toxicity where fifty-percent lethality concentration for Carbon Monoxide levels reach 3900 ppm. Results for these analyses indicated that the ASET of 400+ seconds was higher than the RSET + Safety Factor of 382.5 seconds, meaning that, based on a conservative review, egress during a fire event is satisfactory.