Sitka Apartments

Seattle, Washington

Innovative Heat Recovery and Greywater Reuse in High-Performance Multifamily Housing

Sitka Apartments showcases several advanced technologies that establish it as one of the most sustainable multifamily buildings in the region. Notably, it is the first project in the United States to implement an innovative wastewater heat recovery system for domestic hot water heating. In this groundbreaking approach, all outgoing sewage effluent is collected in a wastewater vault located in the building’s basement. Water-to-water heat pumps extract heat from the effluent before it is released into the municipal sewage system. The captured heat is then recycled into the domestic hot water system, providing an energy source for the following day’s hot water demands.

The building also features a greywater harvesting system, which diverts water from showers and laundry for irrigation, supporting the project’s broader sustainability goals.

Ecotope led the design of the wastewater heat pump system, supported by Bonneville Power Administration’s Emerging Energy Efficient Technologies program. Additionally, Seattle City Light contributed significant energy efficiency incentives, helping to reduce upfront costs and making Sitka Apartments a model of innovation and energy efficiency in urban housing.

Learn more about this project here:

• SLU Multifamily Project Honored for Water-Conscious Design, Seattle Daily Journal of Commerce, May 2024
• In Seattle, the Sitka is Raising the Bar for Environmental Design, Metropolis Magazine, December 2020
• Sitka Apartments, USGBC, 2020