The BUILD UP Skills United (BUSUnited) project is a collaborative initiative under the LIFE Clean Energy Transition (CET) sub-programme aimed at fostering a thriving EU-wide community of practitioners to promote and develop sustainable energy skills among construction professionals. The project aligns with the LIFE-2024-CET-BUILDSKILLS call by addressing the critical need for upskilling and reskilling within the building sector to meet the EU’s ambitious climate and energy goals, particularly the targets set out in the European Green Deal and the 2050 carbon neutrality objective. BUSUnited leverages the success of the BUILD UP Skills initiative, which began in 2011 and has funded over 90 projects across 32 countries, to create a robust community of practice (CoP). It seeks to integrate previous efforts and enhance the capacity of national and EU-level stakeholders through coordinated knowledge sharing, capacity building, and cross-sectoral collaboration. The project plans to initiate, grow, and sustain a dynamic network of ten CoPs focused on critical areas such as sectoral skills needs, innovative training methods, skills recognition, demand-side mechanisms, national skills roll-out, funding sources, and EU synergies. Key objectives of BUSUnited include establishing and supporting these CoPs to foster pan-European collaboration, drive innovation in training methods, and facilitate the large-scale deployment of sustainable energy skills. The project aims to engage over 400 stakeholders, including public authorities, training providers, industry representatives, and NGOs, across its activities. Additionally, BUSUnited will create several impactful outputs, such as guidelines, training tools, policy briefs, funding recommendations, and digital platforms to support the dissemination and uptake of best practices. By aligning with and going beyond existing EU frameworks, such as the Pact for Skills and the Renewable Energy Skills Partnership, BUSUnited will catalyse the deployment of effective upskilling strategies across Europe, contributing to the transformation of the construction sector and supporting the EU’s transition to a sustainable, climate-neutral future.