Environmental Stewardship

Enwave Seattle is committed to being an environmental leader in the Seattle community. As such, the company is continuously looking at ways to improve its operations and help customers reduce their environmental impact. Below are a few examples of how we work to reduce our environmental impact and help our customers meet their sustainability goals.

Renewable Energy from Clean Urban Waste Wood

The biomass boiler plant is operating well within its permitted emissions, as confimed by this third party report.


Clean Energy


Enwave Seattle has a biomass boiler that produces steam using locally-sourced clean urban waste wood. At full output, Enwave Seattle has the capacity to cut Its carbon footprint in half (and that of its customers) by reducing CO2e emissions by about 45,000 tonnes annually. For example, that has the same positive environmental impact as:

  • Planting 1,650 mature trees in the city each year or
  • Eliminating the CO2e emissions from the annual energy use of over 3,700 homes or
  • Removing 4.6 million gallons of gasoline from use in the metropolitan area

More information is available here regarding the biomass boiler's fuel sources, emissions and role in curbing climate change.


In the fall of 2009, Enwave Seattle, formerly Seattle Steam began its conversion to renewable energy by installing a new boiler that can burn clean urban waste wood, making renewable biomass its primary source of fuel. At full load, the biomass boiler reduces the carbon footprint of our customers by 50 percent, and will provide a large boost to the region's sustainability goals.


Membership in The Climate Registry

Enwave Seattle is a founding member of The Climate Registry and has been voluntarily reporting its greenhouse gas emissions since 2007. (Climate Registered Certificate). As a member, Enwave Seattle has committed to measure, verify, and publicly report its greenhouse gas emissions to The Registry. By doing this, the company is able to take effective, proactive action to reduce its emissions.

Click here for more information about reporting to The Climate Registry and for an example of how to calculate the carbon emissions for a typical building on the Enwave Seattle system.

ENERGY STAR Portfolio Manager

Beginning in 2010, buildings in Seattle larger than 50,000 square feet and multi-family buildings with more than 20 units will be required to report their energy consumption through the ENERGY STAR Portfolio Manager. Enwave Seattle helps customers participate in this new benchmarking effort by offering direct access to ENERGY STAR-certified engineers, help input data and perform full building energy audits.

It's important to note that buildings connected to District Energy systems, like Enwave Seattle, tend to receive higher scores than those that are not connected. The ENERGY STAR Portfolio Manager accounts for "source to site" eefficiencies and takes into account losses from all energy suppliers in delivering energy or fuel to buildings.

Click here to read more about award-winning customers and how they have used ENERGY STAR scores to further improve the operations of their buildings.

Waste Water Reduction/Condensate Recapture and Re-use

Enwave Seattle is an advocate of water reduction projects, and re-use of condensate is a natural and easy first step. Steam condensate is distilled water; once it passes through a building's heating system, this water is available to use on site for any number of purposes. Several customers re-use the condensate in their building laundry systems, cooling towers, dishwashers and restrooms. Enwave Seattle works with customers to recommend equipment, design systems, and apply for available rebates and grants through Seattle Public Utilities to help reduce their utility costs.

Click here to read a case study about the benefits of re-using steam condensate.


Click here to read the city's report on Enwave Seattle's wood-fired boiler and air quality.

Seattle Steam