Resource efficiency (RE) is a characteristics of the way resources such as energy and materials are used within everyday activities and it is a critical concern for those working in the fields of climate change mitigation and environmental protection. Resource efficiency affects the rates at which resources are extracted from sources and waste streams such as greenhouse gas emissions and material wastes are generated. This thesis presents six studies in which methods from the fields of management, engineering, and systems thinking were used to evaluate and expand upon existing waste prevention and carbon management methods - two of the real-world approaches being used to improve RE. Insights from these studies were combined to examine RE from several theoretical angles - as a problem of socio-technical transition, as a wicked problem, as a problem full of conundrums, as a problem that can be addressed using systems thinking methods, and as a problem for which an underlying vision has not yet been well articulated and accepted. Key contributions to knowledge from the six studies include: Insights from the trial of a holistic carbon management method for buildings that includes consideration of the interactions between end-use technologies, stakeholder groups, organisational structure, and buildings. The application of critical systems heuristics theory to investigate issues related to competing goals within planning for the low-carbon redevelopment of an urban enterprise zone. A waste prevention model for the UK economy, developed using system dynamics, which produced insights into waste prevention pathways and findings about the usefulness to government of the systems methods used. The development of a theory linking social, economic, technological, and infrastructure factors as an proposed explanation of the causes of Jevons' Paradox; a model of road transport carbon emissions as an application of the theory; and the testing of a suite of four types of interventions that could reduce greenhouse gas emissions enough to meet EU goals by 2030. Key contributions to knowledge from a synthesis of the study findings include: Analysis of RE as a wicked problem, through applying the ten characteristics of wickedness, and implications of this wickedness for RE practice. Analysis of RE as a problem of socio-technical transition, through developing a Causal Stratified Sustainability version of the Multi Level Perspective which portrays the relationship between the natural environment, science, and the economy at different stages of maturity. A proposition for a preanalytic vision for the field of RE, with the intended purpose of moving the field of RE away from its mostly pragmatic stance and developing a theoretical grounding from which to improve RE practice in future. A framework of applicability of systems models and methods to RE. Reflections on the use of PS Ms within the field of RE. Personal reflections on the impact of systems methods on my own understanding, and the dualistic role of engineers with regard to RE.