Retrofitting expresses, in a traditional approach, the process of improving something after it has been manufactured, constructed, or assembled. These systems integrate new technologies, new functions, and new services that increase the energy performance in existing private, public, and commercial buildings. Retrofitting for Optimal Energy Performance is a comprehensive reference source that examines environmentally conscious technologies and their applications in advancing retrofitting practices. Providing relevant theoretical frameworks and the latest empirical research findings in the area, it highlights an array of topics such as climate change, energy management, and optimization modeling, and is essential for academicians, students, researchers, engineers, architects, entrepreneurs, managers, policymakers, and building owners.