To reduce our contribution to climate change, we have invested in clean energy and committed to reducing our operational carbon emissions. We regularly track our annual carbon emissions, energy use, and renewable energy generation. This allows us to implement initiatives to work toward meeting the goals of the City of Portland Climate Emergency Declaration. The declaration adopted a new target for Portland to achieve a 50% reduction in carbon emissions from 1990 levels by 2030, and reach net-zero carbon emissions before 2050.
Since 2007, we have calculated carbon emissions from electricity, natural gas, and fuel use. We report these in a Carbon Footprint Report to understand how and in what quantities the bureau is generating carbon emissions. Regularly tracking and reporting our emissions helps us identify ways to reduce energy use, improve fleet efficiency, and generate or purchase renewable energy. The following table shows Water Bureau operational carbon emissions from the past six years. More detailed information is available in the reports below.
|Calendar year||Total annual carbon emissions (metric tons of C02 equivalent)|
Carbon Footprint Reports
The largest source of bureau carbon emissions is the electricity used to pump water. Although most of the water in the system flows by gravity, pumps are necessary to lift water to higher elevations in Southwest and Northwest Portland, and hilly areas on the east side. In some years, groundwater from the Columbia South Shore Well Field is used to supplement the main Bull Run water supply. Pumping groundwater uses a lot of electricity, so in the years that the bureau uses groundwater, electricity use goes up.
To combat this, we have increased the operational efficiency of pump stations by installing energy-efficient pumps, replacing pump motors, weatherizing pump stations, and installing variable-frequency drives, which adjust the pump's motor speed to save energy. Other significant sources of carbon emissions include the energy used to power our facilities and fuel emissions from our city fleet vehicles.
However, we have made significant strides to reduce our overall energy usage. We've upgraded to more efficient lighting fixtures and installed digitally controlled HVAC systems that adjust temperature automatically in Water Bureau buildings. Newly constructed buildings are in line with the City of Portland's Green Building Policy. Additionally, we have transitioned many of the passenger vehicles in our fleet to hybrid or electric models.
Since 2001, the City of Portland's Green Building Policy has required all new occupied City buildings to be built to green building standards established by the US Green Building Council's Leadership in Energy and Environmental Design (LEED) program. LEED is a rating system for the design, construction, and operation of high-performance green buildings.
Our Meter Shop was certified as LEED Gold in 2010. The green features of the building include the following:
- A 12.24 kW solar array that provides 10 percent of the building's power annually
- An energy recovery ventilation system, which recovers approximately 75 percent of the heat from exhausted heating air
- Energy-efficient lighting such as light-emitting diodes (LEDs)
- A solar hot water system that provides 100 percent of water-heating needs approximately six months of the year
- An Energy Star-rated roof, to reduce the heat-island effect, which can occur when built urban areas are hotter than nearby rural areas.
- Window placement to increase natural lighting and ventilation and reduce energy use
- Building materials made with low percentages of volatile organic compounds (VOCs)
- A vegetated planter to filter and decrease stormwater runoff
Interstate Renovation Project
We completed construction of two new seismically resilient buildings at the Interstate facility in 2014 and 2015: the Maintenance Building and the Shops and Stores Warehouse. Both buildings were designed for LEED Gold certification. LEED components of these buildings include:
- A vegetated eco-roof on the Maintenance Building
- A 78 kW solar array on the Shops and Stores Warehouse
- Employee access to public transportation options
- Stormwater runoff control/bioswales
- Water-efficient landscaping
- Construction waste recycling
- Digitally controlled heating, ventilation, and cooling system
- Energy-efficient lighting