Domestic data sources:

• Current consumption & Efficiency -- by US Energy Information Administration (May notice FAQs by the EIA. It points to more useful topical data sources.)
• Manufacturing Energy Consumption -- by US Department of Commerce, US Census Bureau. You may search this site for more surveys on the topic.
• Database of State Incentives for Renewables & Efficiency®  -- A source of information on incentives and policies that support renewables and energy efficiency in the United States. Searchable by zip code. See also the page on Energy statistics database.

International data sources: 

• Statista - quick statistics and articles on the topic
• UNdata: Energy Statistics Database - browse by topic. 
• International energy and data analysis by US Energy Information Administration (EIA)

Additional sources:

• U.S. Department of Energy Data Explorer -- Collections of files, figures and data plots, multimedia and images, computer simulations, specialized databases, and interactive data maps.
• Energy Efficiency -- By IEA, provides reports, articles with date on the topic.
• UN Statistics Division: Energy Statistics -- Provides energy data from statistical agencies throughout the United Nations. Series on energy cover topics such as consumption, exports, imports, and production. 
• American Council for an Energy-Efficient Economy (ACEEE) (This site provides rich information and data on energy efficiency. You may navigate or search within the site to locate needed information.)

You may also use the key reports such as: 

• World Energy Outlook by International Energy Agency (IEA)
• Energy Economics by BP.com (This site provides rich data and reports.)