The literature has shown the power of social norms to promote residential energy conservation, particularly among high usage users. This study uses a natural field experiment with nearly 200,000 US households to explore whether a financial rewards program can complement such approaches. We observe strong impacts of financial rewards, particularly amongst low-usage and low-variance households, customers who typically are less responsive to normative messaging. Our data thus suggest important policy complementarities between behavioral and financial incentives: whereas non-pecuniary interventions disproportionally affect intense users, financial incentives are able to affect substantially low-user, "sticky households."