Stack House Apartments is the new construction component of the redevelopment of an entire city block in the emerging South Lake Union neighborhood of Seattle. The project is certified Platinum under the LEED for Homes Mid-Rise Rating System and meets the energy and water consumption requirements of the Seattle 2030 District high-performance building challenge.
Stack House consists of two mid-rise buildings, providing 279 apartments and roughly 9,000 sq.ft. of commercial retail space. This exemplary use of an infill site creates a development density of 182 units per acre! The rest of the block is occupied by the Supply Laundry building, a historic landmark, which has been restored and adapted for an additional 30,000 sq.ft. of commercial space and is also pursuing LEED Platinum.
Developer Vulcan Real Estate commissioned O’Brien & Company to facilitate the pre-design process for the project, during which they set ambitious performance targets including LEED Gold or Platinum certification and an Energy Use Intensity (EUI) of 28 kBtu/sqft/yr to comply with the Seattle 2030 District requirements for energy and water consumption. In addition to these performance goals, the design team, led by Runberg Architecture Group, focused on maximizing amenities for tenants in this dense urban area, including view corridors to Seattle landmarks and accessible green spaces, such as an indoor, unconditioned “wintergarden” that offers sheltered access to green space even in the cold and damp of winter.
Other green features of the project include:
- Extensive green roof area, including an urban agriculture pea patch on the primary residential roof deck.
- Rainwater harvesting and 42,000 gallons of cistern storage provide more than 60% of irrigation demand for external landscapes, the “wintergarden” and green roof areas.
- Elevator stacks are isolated from the corridors to reduce energy needed for ventilation and space conditioning.
- A reverse cycle chiller that uses waste heat from garage ventilation exhaust to pre-heat domestic hot water, reducing energy demands for hot water by a factor of three.
- Very high efficiency plumbing fixtures reduce residential water consumption by 50%.
- Mini-split heat pumps replace electric resistance heat in many of the south and west facing units and also provide cooling, while still reducing unit space conditioning consumption by 50%.
In addition to early design facilitation, O’Brien & Company also acted as the LEED for Homes Provider and Green Rater, offering quality assurance and verification oversight of the design and construction process. Given the high performance expectations, O’Brien & Company’s field team worked closely with the general contractor, Exxel Pacific, and their sub-contractors to ensure the construction details necessary to achieve the performance requirements were clearly understood. They also provided in-field training and feedback on implementation using both visual verification and performance testing to build the construction team’s capacity and ensure a successful certification outcome.
The project was awarded LEED for Homes Mid-Rise Platinum certification in December, 2013.
2014 NAIOP’s “Night of Stars” Award for Mixed Use Development of the Year