Recent research has revealed several shortcomings of design processes with respect to modern contexts. Two of these are complexity and sustainability. Design problems are becoming increasingly complex, to the point where designers can be easily overwhelmed. Sustainability, while recognized as pivotal to future human progress and well-being, remains largely disconnected from design processes. Current practices in the field of sustainability are not integrated into the design process and thus, are often carried out only as after-the-fact addenda. The goal of this research is to address these two problems with current design processes. It has long been known that analogies are useful and help to reduce complexity by rooting a topic into pre-existing knowledge of the user. Patterns have also been shown to be useful in helping solve complex problems in engineering, as well as architecture and computer science. Therefore, this dissertation proposes a new design framework which: reduces problem complexity through the use of an analogy and patterns, makes provisions for emergent properties within the patterns and the framework, and provides a means for generating solutions with aspects of sustainability via the patterns and evaluation criteria. The analogical framework, based on similarities found in the phenomena and processes between natural systems (nature) and design, is then used to formulate a new model for describing the design of a product, the Design Genome. The main focus of this dissertation is to use this model as a basis for a new method of concept generation, the Design by DNA method, and concept evaluation, the Fitness Space method. It is shown that the Fitness Space method has the potential to solve many, if not all, of the downfalls of conventional evaluation methods. A pilot experiment testing the Design by DNA method against previously known design methods is conducted and demonstrates the feasibility for a full-scale experiment. Even with small population sizes, results from the experiment show promise that the DbD method is useful as a tool for the concept generation process. Based on the work done, it appears that Design by DNA and the Fitness Space are promising approaches for improving design processes.