©2013 This excerpt taken from the article of the same name which appeared in ASHRAE Journal, vol. 55, no. 6, June 2013.
By Jeremy McClanathan, P.E., Associate Member ASHRAE
About the Author
Jeremy McClanathan, P.E., is senior energy analyst at CDi Engineers in Lynwood, Wash. He is an ASHRAE certified Building Energy Modeling Professional and a Healthcare Facility Design Professional. He is a member of the Puget Sound ASHRAE chapter.
Health-care buildings currently consume 9% of all building energy and 4% of the total energy consumed in the U.S. Designers of Swedish Issaquah decided to use a central plant heat recovery system to make the hospital one of the most energy efficient in the U.S. The facility includes a 353,000 ft2 (32 515 m2) acute care hospital, a 200,000 ft2 (18 581 m2) medical office building, and a stand-alone central utility plant (CUP). The acute care part consists of two four-story wings with 175 beds. Construction began in May 2009, and the hospital opened in July 2011.
Setting the Stage
The Swedish leadership team decided to take a critical look at the past performance of Swedish’s existing facilities in the Seattle area. They reviewed the mechanical systems, energy budgets, control strategies, maintenance logs, and forged these findings into a plan for reducing energy and increasing operational efficiency for the new facility.
Swedish’s corporate facilities engineering group, with support from senior management, set a goal for the acute care hospital part of Swedish Issaquah to achieve an energy use intensity (EUI) of 150 kBtu/ft2•yr (1 703 550 kJ/m2•yr. Greatly increasing the challenge, the owner also dictated that the design and construction schedule would total just over two years, which is about one year less than a traditional design-bid-build project of similar magnitude. It was quickly determined that an integrated project delivery (IPD) approach would be necessary to meet schedule.
Occurring in parallel with the development of the Swedish Issaquah was the ongoing work and research being done by the Integrated Design Lab (IDL) of the University of Washington. Funded in large part through a grant from Northwest Energy Efficiency Alliance (NEEA), IDL was developing new strategies for reducing energy use in hospitals by drawing on the expertise of local architects and engineers. The Swedish project mechanical engineers were early contributors.
When the study began, IDL realized that most of the health-care buildings were designed at code minimum with a CBECS EUI of 250. Its roadmap “Targeting 100!” was developed to provide designers the tools, options and strategies to meet the 2030 challenge and still abide by the stringent code requirements unique to health-care buildings.
When the engineering team began to integrate the impact of the schedule and energy targets into its work plan, we realized that “mechanical design as usual” would not work. To drive the EUI down to the targeted level required a different technical approach than had been used on other recent projects, and also required a well-orchestrated and committed stakeholder involvement throughout the process.
With the aggressive schedule looming, the engineers knew decisions on mechanical systems needed to be made prior to completing the schematic design phase. An energy model needed to be developed unusually early in schematic design so that key design decisions could be made early, and then follow-up testing could be done “on the fly.” This model would have to be accurate to the degree that precise energy and cost decisions could be made with equipment ordered and shipped well in advance of what could be achieved through a traditional delivery process.
A new energy modeling protocol was developed to “design in the model,” to help the team make informed decisions and provide accurate information about building systems, and components from pumps to chillers to VAV terminals and duct performance. Importantly, the new modeling protocol gave the team accurate return on investment (ROI) data that made system and equipment selection meaningful.
Read the Full Article
Return to Featured Article Excerpts