In this empirical study, we explore the user acceptance of smart home technologies by asking: How do people perceive their opportunities and drawbacks? What factors shape their perceptions? What implications does this have for future energy savings, sustainability, and policy? Based on a mixed methods approach involving three focus groups (N = 18) and a nationally representative survey of adults (N = 1032) in the United Kingdom, we explore the demographics, preferences, and risks of smart home technology. We do this via the lenses of knowledge and adoption; energy and climate sustainability; and vulnerability and exclusion. We explore how different classes of people—adopters versus non-adopters, high-income versus low-income, women and men, old versus young—support or oppose smart home technologies, have different degrees of knowledge and misperceptions, and reveal very different perceptions about the practices enabled by smart homes. In doing so, we show at times compelling links between smart homes and energy consumption, and possible negative impacts to poverty, inclusion, and empowerment.