Andy Walker is a recognized authority on solar energy and a thought-leader in optimization of energy systems. He currently serves as Principal Engineer at the National Renewable Energy Laboratory, where he conducts engineering and economic analysis of energy efficiency and renewable energy projects for Federal agencies such as national parks and military bases and also for commercial and industrial clients. He invented the Renewable Energy Optimization (REO) method of planning renewable energy projects across a portfolio of properties based on economic value. He has taught several classes including "Introduction to Solar Engineering" and "Design of Solar Buildings" in the Mechanical and Architectural Engineering Departments at the University of Colorado at Boulder, "Introduction to Energy" at the Colorado School of Mines, and "Advanced Energy Technology" at Metropolitan State University of Denver. He serves on the Executive Committee of the American Society of Mechanical Engineers Solar Energy Division; has been an Associate Editor for the Journal of Solar Energy Engineering; and was Technical Program Chair (2009) and General Program Chair (2011) for the ASME Energy Sustainability Conference. Prior to joining NREL, Dr. Walker worked at the Colorado Office of Energy Conservation and at the Solar Energy Applications Laboratory at Colorado State University. As a Peace Corps Volunteer in Nepal, he taught math and science and completed several projects including a passive solar school dormitory and a village-scale biogas generator. He conducts renewable energy training for developing countries for the U.S. Agency for International Development, the UN, and other agencies. Dr. Walker is the author of over 28 book chapters, journal articles, and conference papers including "Solar Energy: Technologies and Project Delivery for Buildings" published by John Wiley and Sons and chapters on Solar Energy Systems; Health Comfort and Productivity; Green Design Process and Associated Costs in "Green Building; Project Planning and Cost Estimating" now in 2nd edition published by RSMeans. He has been recognized with 12 awards from government agencies including certificates from President Ronald Reagan, Colorado Governor Roy Romer, and an award from the Association of Government Communicators for the publication "Procurement of Architectural and Engineering Services for Sustainable Buildings"; and from professional associations including ASHRAE; ASME; IREC; and others. Dr. Walker's credentials include a B.S., M.S., and Ph.D. in Mechanical Engineering, and he is a registered Professional Engineer in the State of Colorado. Recent interests include integrating large solar energy projects into electric grid systems and hardening telecommunications infrastructure using distributed solar energy resources.