A smart home is a house that is responsive to its inhabitants and their actions by being aware of their context. Potential applications for smart homes address economic and comfort aspects of living, or could provide unobtrusive support for the elderly or disabled to promote independent living. The basic building blocks of such a smart home is a computing system consisting of distributed sensors and actuators. Programming and maintaining such an infrastructure is challenging because suitable programming abstractions are currently missing. In this paper we introduce the notion of programmable space that lets the application developer perceive the smart home as an integrated runtime environment. This approach is implemented in a system called RuleCaster. Applications are developed in a high-level rulebased language. Our approach shows a notable simplification of application development and maintenance. To verify the utility of RuleCaster we use a scenario-based evaluation method.