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Supply Laundry Historic Retrofit via Outcome-Based Energy Code

Case Study by Chris van Daalen, Principal Investigator
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Supply Laundry Historic Retrofit via Outcome-Based Energy Code
Photo credit Vulcan Real Estate
Historic Building Energy Retrofit
Outcome-based compliance
City of Seattle
Shailesh Desai, Structural Plans
City Investors XVIII LLC
Runberg Architecture Group
Exxel Pacific Inc – general contractor
EcoTope – Mechanical Engineer
LEED-CS Gold Certification (pending) 2013 Historic Seattle Sustainable Preservation Award


Adaptive redevelopment of the historic 110-year old Supply Laundry building, vacant for over a decade, required an upgrade to the stringent 2009 Seattle Energy Code.  To maintain as much of the architectural character as possible, the owners partnered with the National Trust for Historic Preservation and the City on the nation’s first outcome-based energy code pilot project.  In exchange for access to post-occupancy performance data, the City granted code flexibility in how energy targets were to be achieved.

Permitting Process

This adaptive historic redevelopment required a change of use from heavy service to retail / office, and was approved under the 2009 Seattle Energy Code through the City’s Outcome-Based Energy Code pilot project.   City regulators allowed extraordinary flexibility in building and energy design, so that the design and development team could maintain the historic commercial laundry’s architectural integrity, while still meeting the stringent efficiency goals of the Seattle Energy Code.  Instead of following the prescriptive code, system analysis or component performance path, the building’s actual energy performance will be analyzed 12 months post-occupancy to determine compliance with standards, with specific enforcement procedures defined for non-compliance.  This outcome-based path has since been incorporated as a recognized fourth compliance path in the 2012 Seattle Energy Code, called the Target Performance Path.

Code RequirementCompliance Path

2009 Seattle Energy Code: 1412.8.1.  Requires economizer; 1323 Fenestration requires double-glazing; 1322 Opaque Envelope requires insulation to compliance with nominal R-values

Outcome Based Code pilot program gave building inspector flexibility to depart from current energy code.  Applicant proposed code alternates mitigated by the outcome based energy code, which were approved.  Ultimate compliance requires verification at 12-months post-occupancy

2009 Seattle Energy Code Reference Standard 29 (Modified version of Appendix G, ASHRAE Standard 90.1-2007) requires proposed building to consume 5% less energy than a modeled code-equivalent new building.

Energy modeling including all proposed energy savings measures shows project saving 50% or more over baseline (See energy model report)

Compliance Details:

To achieve compliance, the project team was required to submit design documents and respond to Seattle DPD Corrections and questions with answers on how the building as a whole would reach the performance target, and how specific measures complied with code. They also conducted energy modeling, with the inputs and assumptions reviewed and critiqued by DPD staff.

Commissioning requirements included a commissioning plan (in writing), systems balancing, functional testing of HVAC and lighting systems and controls; and an air infiltration test. A Memorandum of Understanding spelled out reporting requirements to ensure the actual building performance met the EUI target of 50% better than a modeled code-equivalent new building. If the project failed to meet its target, mitigation measures would be identified through an ASHRAE Level II Energy Audit, and those deemed most effective and cost efficient would be implemented.

Project Description

Built in 1906 and vacant for more than a decade, the Supply Laundry Building is 2-story brick historic structure, in the heart of the rapidly developing South Lake Union area of Seattle’s urban core. This economic hotbed is home to the campus being developed by Vulcan Real Estate. The historic building was recently renovated and is now occupied by a restaurant, other retail and office space.  It is part of a whole-block mixed-use development that includes the 287-unit Stack House apartments, interior courtyards, green infrastructure, public art and other amenities - designed to be a vibrant live-work urban space for the tech industry workforce.

To renew the landmark building, a brick masonry smokestack was structurally reinforced and restored; the building’s masonry exterior was cleaned and restored, and post-WWII concrete block additions to the building were removed.  The original wood windows were restored, and the rest - aluminum windows installed in the 1950s - were replaced with new energy efficient single-hung wood-clad windows that resemble the originals (20% restored, 80% replaced). In the process, many original openings were reclaimed.  On the interior the original heavy timber, post and beam structure is visible, and about 20 percent of the masonry walls remain un-insulated to maintain exposed brick and some of the historic character of the building, while other exterior walls were upgraded with a high-performance insulative assembly. The roof renovation was a challenge due to varying conditions after more than 100 years of renovations and maintenance, but the design specified an R-38 average value with at least R-10 at the lowest points.

Design / Build Process

The energy retrofit was designed to perform 30 percent better than the stringent Seattle Energy Code, and use 50% less energy than the average comparable baseline building (specified in Reference Standard 29 (Modified version of Appendix G, ASHRAE Standard 90.1-2007)), while still maintaining Supply Laundry’s historic architectural integrity.  Departures from the rigorous energy code allowed the owners to tailor energy efficiency measures to the building’s unique character, while optimizing the value of their investment. Fortunately, Seattle Building Code already offers flexibility for historic buildings, providing a better path to approve such departures.

The building uses a passive, hybrid heating, ventilation and cooling (HVAC) system, in short, relying on occupants to regulate temperature and ventilation by opening and closing windows, augmented by automated lighting, thermal controls, and variable refrigerant flow (VRF) split system air-source heat pumps for supplemental heating and cooling. Because of this passive approach, the engineer determined that economizers were not necessary to achieve energy performance targets and ventilation requirements, though they are required for many buildings of this type undergoing a change of use.

In exchange for this flexibility, the owners signed an agreement with the National Trust for Historic Preservation (NTHP) and the City of Seattle, agreeing to track and share energy data for all building energy systems using metering equipment generating real time data. This data monitoring not only measures project performance for compliance, it also helps inform and guide occupant behavior.  Since energy use is so heavily influenced by behavior, occupants will get instant feedback from their NEST smart thermostats via smart phone app!  In addition the owner is requiring lease provisions that guide tenant improvements, require monitoring and automation, and allow access to data for individual tenant spaces.

Lessons Learned

According to the NTHP “Supply Laundry is an ideal project for this work. As a mid-sized brick building undergoing a substantial renovation and change-of-use, lessons learned from this project will be broadly applicable to much of the nation’s smaller, older building stock. The overall objective of Seattle’s pilot is to show that with a more flexible approach, owners of older buildings can achieve aggressive aggressive energy targets, retain valuable historic features and optimize return on investment in terms of both energy savings and dollars.”


“Driving Innovation, Rewarding Performance: Seattle’s Next Generation Energy Codes and Utility Incentives” by Meghan Pinch, Scott Cooper and Brendan O’Donnell, Seattle City Light, Ric Cochrane, Preservation Green Lab and Duane Jonlin, City of Seattle DPD. Seattle Energy Code, Target Performance Path, see sec C402.15
Getting to Outcome-Based Building Performance: Report from a Seattle Summit on Performance Outcomes Outcomes based energy code website of National Trust of Historic Preservation (includes other case studies of the project)
"Historic rehab a test for performance-based codes" by Brandon Morgan, Vulcan Real Estate New Buildings Institute Outcome Based Energy Code website
Saving History, Saving Energy, article by  Jonathan Heller, P.E., Member ASHRAE, in excerpted from an article of the same name which appeared in ASHRAE Journal, vol. 58, no. 4, April 2016. .


Post occupancy energy performance “outcome” data is due out in 2016, at which point the building will achieve compliance, or take corrective measures. NTHP plans to publish case study with results sometime thereafter.

Project Contacts
Owner: Brandon Morgan Vulcan Real Estate (206) 342-2000 Approving Offcial: Shailesh Desai City of Seattle (206) 233-7860 Designer: Melissa Wechsler Runberg Architecture Group, PLLC (206) 956-1970
Subcontractor: Morgan Heater EcoTope LLC (206) 322-3753
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