The Energy subseries is the largest in Hildt's subject files and reflects Hildt's work as Chair of the Energy Committee from to 1982 to 1985. The City of Seattle contracted with the Bonneville Power Association (BPA), part of the U.S. Department of Energy for power, during this time period. BPA was created in 1937 to act as marketing agent for power from Bonneville Dam on the Columbia River. Executive, Legal, Council, and City Light perspectives are documented in the renegotiation of the City's contract with BPA in 1981 and 1982. One of the issues for the City was it felt that the BPA discouraged the development of resources by City Light to serve its own load.

The City's efforts at conservation are well documented, especially the implementation of the Comprehensive Residential Weatherization Program (CRWP), created in 1981 through Ordinance 109675. Constituent mail, interdepartmental correspondence, reviews and reports document the many individual programs within CRWP. The Reports and Studies documenting CRWP are useful for following implementation of the weatherization programs; quarterly and other reports are included. The researcher should also check for accompanying material in the Published Documents Index, as published documents were cataloged separately in the Publications database.

The City also explored other hydroelectric projects, such as one at Copper Creek on the Skagit River and Rocky Brook on the Olympic Peninsula. Economic and environmental concerns relating to these proposals are documented in Hildt's records.

The Energy, Ltd. Project, begun as a federally-funded citizens' committee, is well documented through correspondence between the Citizens Committee, Mayor, City Council, and City Light, as well as minutes and progress reports of the Committee and issue papers. The goal of the Energy, Ltd. Project was to identify the role of local government in developing a community conservation and management plan for fossil fuels. Several issues facing Seattle City Light in the early 1980s are touched upon in Hildt's records. These include rate increases, various programs such as Project Share, and management and work environment issues at City Light.