Managing Consultant
Sierra Spencer

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Sierra Spencer

she / her / hers

Sierra Spencer joined E3 in 2019. Her work focuses on analyzing opportunities to leverage distributed energy resources and supporting clients’ transportation electrification and renewables integration efforts. Sierra’s work often incorporates an evaluation of distributed energy resource adoption and energy-related costs through the lens of equity and affordability. Sierra has also worked on long-term resource planning with an emphasis on meeting emission reductions goals while maintaining system reliability.

Sierra credits her study abroad experiences in South Africa, New Zealand, and Australia with sparking her interest in energy and the environment. As a student, she conducted yearlong research studies on managed charging for electric vehicles and the use of sustainable biofuels for heating.

Consulting at E3 allows Sierra the opportunity to develop creative solutions for some of society’s most pressing challenges for clients who are motivated to implement them. She is thrilled to contribute to E3’s mission and cutting-edge work after encountering E3 throughout her education.

Sierra, a former college athlete, stays active by running, swimming, and paddleboarding. She’s also an avid hiker and traveler.

Education: MS, civil and environmental engineering, University of California, Berkeley; BS, engineering and BA, environmental studies, Swarthmore College


Electrification of Transportation Rate Design and Infrastructure Applications | Hawaiian Electric Company, 2020-2021

E3 supported the Hawaiian Electric Company (HECO) on four transportation electrification filings. First, E3 and its subcontractors Anser Advisory and Black & Veatch designed a program for HECO to build the make-ready infrastructure for electric buses to support electrification of transportation for transit, tourism, and other bus operators. Second, E3 designed two new electric vehicle charging rates, EV-J and EV-P, for commercial electric vehicle charging sites. E3 developed a rate design calculator and performed cost-benefit assessments to evaluate different rate designs and propose final rates that will support low-cost public EV charging in Hawaii. Third, E3 and its subcontractor Anser Advisory supported HECO in developing its Charge Ready Hawaii pilot program to deploy make-ready charging infrastructure for commercial and multi-unit dwelling locations. Finally, E3 and its subcontractors Anser Advisory and Atlas Public Policy supported HECO in developing a proposal to expand its public DC fast charging (DCFC) infrastructure pilot to build out 150 DCFC ports and 150 dual-port Level 2 charging stations across its service territory. These programs – three of which have been approved by the Hawaii Public Utilities Commission with the fourth project (DCFC program expansion) under review in 2022 – build on HECO’s Electrification of Transportation Roadmap and allow for HECO to support its customers in electrifying their vehicles and fleets.

Time-dependent valuation for building codes | CEC, 1999–present

E3 supports the California Energy Commission (CEC) in implementing the state building energy code by maintaining the economic framework for energy standard requirements and allowed trade-offs for new construction. We have worked with the CEC and its stakeholders since 1999 to continually refine a time-dependent valuation (TDV) methodology, and we are now under contract to support the 2025 Title 24 Update. The TDV methodology uses a 30-year forecast of the social cost of energy that varies hourly and by location to account for shifts in system peaks over time, and regional variations in climate and grid utilization. . E3’s initial study investigated a shift to a value-based standard that accounts for the time and geographic differences in energy costs seen in California energy prices, natural gas and propane markets, as well as in the costs of electric utility distribution and transmission systems. TDV was initially adopted in 2005, and E3 supported the updates in 2008, 2013, 2016, 2019, and 2022.