Solving environmental and ecological problems is impossible without an understanding how people and organizations behave. We work with companies and governments to design and evaluate behavioural interventions aimed at promoting energy efficiency, low carbon transformation, and sustainability at large. We use experimental methods such as randomized control trials, online and laboratory experiments, to estimate the causal impacts of environmental policies and programmes. We combine these with data science methods to interpret and model observed behaviour from smart sensors and other digital devices. We have applied these approaches both in developed and developing countries, helping better understand energy and water use, waste recycling, and investment decisions.