Oakland fancies itself a green town, but there’s always room to grow — even if only to upstage pesky Berkeley. In recent years, US cities from New York to San Francisco have embraced greening measures geared toward reducing energy consumption in downtown business districts. Now Oakland’s getting in on the act. Oakland Shines, launched by Mayor Jean Quan earlier this month, will offer technical assistance and cash rebates to downtown businesses over the next two years in order to promote energy-efficient lighting and refrigeration products as well as HVAC improvements.