Buildings are major contributors to energy use and environmental impact in developed societies. If theambitious sustainability targets of modern societies are to be met, energy use in the built environmentmust be addressed as a central issue.New momentum on achieving energy efficiency in the building sector has been triggered by informationand communication technology (ICT). New opportunities bringing the concept of smart building closerto reality are offered e.g. by innovative sensing techniques, extensive and cost-efficient data collectionand analysis, advanced controls and artificial intelligence.However, these opportunities are associated with cost and uncertainties regarding whether theinvestment costs are paid back in terms of energy savings, whether indoor comfort and air quality andimproved, the drawbacks in term of increased maintenance effort, complexity, reliability and resilience,the effects in terms of user interaction, how data security is affected and the long-term effects on society.This paper critically analyses recent research findings and reviews the pros and cons of some promisingICT techniques being applied in the building sector. It exemplifies drivers and barriers to implementationof advanced controls and artificial intelligence in buildings, based on findings from two test-beds inStockholm, and discusses the implications of these findings for future research.