9th and Thomas


9th and Thomas – Integrating Trades for Improved Outcomes

The design of this 12-story mixed-use project emphasizes adaptability. The building’s massing is in the in the form of a cascading cube, where a strong corner position is softened with setbacks, exposed terraces and inset covered terraces on nearly every floor.

Large, operable windows along the façade allow the building to adapt to Seattle’s ever-changing weather conditions, giving the upper-level office tenants the ability to control their spaces with natural ventilation and daylight. A fourth-floor roof garden and series of outdoor terraces running up the building continue the emphasis on occupant wellness. The project is LEED® Gold certified.

9th & Thomas is designed to be a central neighborhood gathering place. Activated by retail and restaurant spaces, the public “living room” lobby is home to a range of curated arts programming. The building’s inviting street presence establishes 9th & Thomas as a contextual community hub – one that serves the rapidly evolving South Lake Union neighborhood today and into the future.

The building boasts a three-story podium, mid-level roof garden, and a residential penthouse. A central VAV DOAS air handling unit serves TI spaces to use 100% outside air and recover heat. The residential HVAC design included a radiant heated/chilled slab coupled with semi-custom DX AHUs with electric heat. A chiller plant with heat-recovery chillers circulate cooling water to the DOAS and TI hydronic cooling terminal units was added along with a heating plant that included two, gas-fired condensing water heaters.

 Anticipating the Market

9th & Thomas was permitted under 2009 Seattle Energy Code (SEC), but the building ownership knew that the building would need to compete in a market that was undergoing significant change. McKinstry worked to clarify the impacts of the impending 2012 SEC changes and explain the likelihood of a market shift towards DOAS and hydronic terminal systems. Weighing competing project values of cost and deep sustainability, the ownership team decided to future proof the building mechanical systems by voluntarily installing a 2012 SEC compliant system.


Once a decision was made to build using steel-framed construction, McKinstry went to work helping validate floor-to-floor heights and confirming ceiling heights for a future tenant. The entire design team worked together to coordinate the minimum floor-to-floor heights that would meet ceiling height expectations. McKinstry came to the table with pre-detailed major duct and pipe runs on a typical floor, allowing the team to identify key structural modifications that would need to be incorporated to squeeze into every inch. This process drove towards a better value to the owner, and an amazing open experience for the tenant.

designed for a tech tenant?

The original design from the project inception did not include sufficient cooling capacity to accommodate a tech tenant. The allowable occupant and plug load densities of the S&C system were significantly lower than BOD requirements for the largest potential tech tenant in the neighborhood. At S&C completion, a dense tech tenant completed a due diligence review, and ultimately decided only small modifications to the S&C system cooling capacity were required to accommodate at TI buildout. The building has been operating without any critical shortages to cooling capacity, indicating tech tenant BOD criteria may have extra conservatism

Relevancy to future projects

We plan to use our well-established design and preconstruction process, further refined from 9th & Thomas, to benefit future projects in the following ways:

Confirm Owner BOD Criteria Early

Many buildings are over-built due to overly-conservative design criteria, which ultimately results in an inefficient deployment of the owner’s money. We prefer to spend time benchmarking plug load and occupant density, in part to validate and challenge overly-conservative BOD sizing criteria.

Plan for TI Layouts Early

Using detailed construction knowledge early in the process can create opportunities to find significant benefits in construction efficiency. It’s possible that a few haunches and penetrations can be coordinated and “create” additional inches that can be used to reduce floor-to-floor heights (and overall construction cost), increase achievable ceiling heights, or both.

Designing for the Future

Hydronic systems are inherently flexible and allow for the addition of more efficient equipment in the future. We can design flexibility, space, and future expandability at the right value point to allow for big shifts in the future, whether that be an EcoDistrict, TI restaurant heat recovery system, or more efficient piece of mechanical equipment.


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