The development of the complete and complex Single Information Space for the Environment in the Europe (SISE) covering all interactions among environmental information and knowledge using current ICT tools is practically impossible. A common methodology of building the conceptual model of the SISE, based on ontologies and associated technologies was developed at Masaryk University. The big challenge is to find the best way how to make ontology semantics available to the user using appropriate problem solving (search) interface. The paper shows the concept of a SISE semantic interpretation, related summary of used technologies. The concept combines main advantages of ontologies and expert systems - the ontology semantics and the rule based on application are used for searching information and issuing predictions.