This report provides an analysis of the conceptual and detailed design of zero energy buildings, specifically focusing on the 'waste house' project at the University of Brighton. It explores the principles of zero energy buildings, which aim to provide indoor comfort with minimal energy consumption, contributing to environmental sustainability. The report covers key aspects such as needs definition, preliminary and detailed design phases, system testing, validation processes, and optimization strategies. It examines various design elements like insulation, renewable energy sources (solar panels), efficient HVAC systems, and water heating systems. The analysis includes the application of the V-model for design, building energy modeling, and project resource modeling. The report also highlights the use of waste materials in construction and the importance of energy-efficient practices to minimize carbon emissions and promote a sustainable future. It references several sources to support the findings and conclusions, emphasizing the importance of zero-energy buildings in the context of global climate change and the need for sustainable building practices.