This book presents a methodology for the design, construction, monitoring, optimization, and post-occupancy evaluation of net-zero and positive-energy communities based on the experiences gained in the EU Horizon 2020 ZERO-PLUS project. It describes the steps, tools, and methods developed during the project, providing practical information for the energy and construction sector that will be of interest to students, engineers, architects, developers, and professionals working around high-performance architecture and sustainable communities.Through the ZERO-PLUS project, a consortium of 32 partners from eight countries, including academic institutions, technology providers, architects, and construction companies, designed four communities covering completely different geo-climatic regions, construction practices, and cultural backgrounds in Cyprus, Italy, France, and the UK. The communities were designed, optimized, constructed, monitored, handed over to tenants, post-occupancy evaluated, and troubleshooted through a system of continuous collaboration and data acquisition. This book presents these case studies and shows how the project targets of reducing electricity consumption below 20 kWh/m2/y, increasing electricity production from Renewable Energy Systems to over 50 kWh/m2/y, and at cheaper costs when compared to current zero-energy buildings were reached and surpassed. These cases demonstrate that a holistic and interactive approach to design and construction can bring communities to a high standard of sustainability.