Sustainability is increasingly imperative for contemporary architects to understand. Yet high performance architecture, and its myriad of applications, is an incredibly broad topic. Thus, this research thesis presents a highly focused study of sustainable architecture through the lens of one specific building type, the library- namely modern ones. Manifesting themselves in countless architectural styles and forms, libraries have a long, rich history throughout civilization. Similar to museums or churches, they are often defining structures in their urban fabric and constructed with a sense of longevity in mind. In the 21st century, sustainability is integral to the success of any long lasting building. Modern libraries can and should exemplify these sustainable practices as well as adapt to changing societal and programmatic expectations for the digital age.