This is an excellent book. It provides a comprehensive overview while supplying specific design applications on the topics of natural and electric lighting. It illuminates many technologies and design principles with straight forward language and clear reinforcing graphics.
I teach architectural lighting at the School of Architecture at the University of Hawaii. I have reviewed many lighting books for this class and have found the Egan and Olgyay text to be very appropriate for the beginning and advanced student as well as a very useful desk reference for design proessionals.