Electric utilities; high energy demand customers; State Corporation Commission to establish electric demand flexibility programs. Directs the State Corporation Commission (the Commission) to establish by regulation demand flexibility programs for Dominion Energy and Appalachian Power Company by January 1, 2028, and for certain electric cooperatives by January 1, 2029, and to reassess such programs every three years thereafter. The bill defines "demand flexibility" as measures designed to lower total electric grid system load requirements from time periods of peak system demand to time periods of lower system demand by requiring or incentivizing retail electric service customers to temporarily reduce or interrupt their electricity usage or by permitting certain retail electric service customers to secure electric load reductions from other retail electric service customers during time periods of peak system demand or other events that cause strain on the electric grid in the Commonwealth. In establishing such programs, the Commission is directed to determine appropriate demand flexibility standards for each applicable utility and avoid shifting or imposing any costs of program participation or administration onto other retail electric service customers. The bill directs the Commission to initiate proceedings by September 30, 2026, for Dominion Energy and Appalachian Power Company, and by September 30, 2027, for cooperatives.