Building environment plays an important role in ensuring a healthy and productive environment for indoor occupants. However, with the increasing demand for comfortable thermal environment and the call for sustainable building operation, achieving a balance between energy consumption and user's thermal preference is challenging. From the informatics perspective, previous studies mainly focused on intelligent building system and occupants activity analysis, while the research on knowledge discovery from building information for optimized building operation is less emphasized. In this paper, we propose a framework for information processing and knowledge discovery for sustainable building environment. Using ubiquitous wireless sensor networks, we showcase how we can feasibly collect and analyze sensory data for the benefit of building environmental assessment and building system control. A case study involving indoor environmental monitoring at two university offices is presented to showcase our approach. We then conclude our work with some discussion on future works.