The time for reaching the necessary cuts in energy use and CO2 emissions is running out quickly and increasing energy efficiency in households substantially is a prerequisite for reaching these goals in time. Behaviour science has provided deep insights into mechanisms of behaviour change in this domain in a large number of small-scale pilots. However, the urgency of the task makes it necessary to role-out such intervention programs lagre-scale and quickly. This requires knowledge on how behaviour science based intervention programs can be provided in real-life situations, on large scale, and resource efficient by real market actors. To address this knowledge gap, the ENCHANT consortium and research approach have been carefully designed to systematically evaluate existing knowledge on energy efficiency interventions, reanalyse existing data in the field, design realistic intervention packages, and implement them on 10 million households in six European countries with a large group of user partners of different types (energy providers, municipalities, NGOs) testing different communication channels. This unprecedented intervention program allows testing a large selection of intervention types addressing a large variety of psychological biases alone or in combination and evaluates their realistic saving potentials. ENCHANT evaluates the performance of intervention campaigns not only with respect to energy and CO2 saved, but also cost effectiveness, and effects on well-being of the participants (with a focus on gender specific effects), as well as effects for target groups in energy poverty. The knowledge created in ENCHANT will be implemented into an algorithm-based webtool which supports decision making of policymakers, energy providers, NGOs and municipalities in designing effective and targeted energy efficiency campaigns. In short, ENCHANT will bridge the gap from knowledge to impact.