The OpenBuildingControl project develops tools and processes for the performance evaluation, specification and verification of building control sequences. This paper describes the tools developed to verify that building control sequences are implemented as specified in a vendor-neutral, executable specification. The verification is done by testing whether trended time series, compared to the simulated control response, are within user-specified tolerances for time and for the trended variable. Morever, sequence diagrams are used for inspection of the control response. The paper gives an overview of the OpenBuildingControl process and describes tools for the control verification. It presents and example in which we successfully verified that an actual implemented control sequence conforms to its vendor-independent specification. It closes with discussion of experiences collected during this verification and with alternate approaches that can improve the operational performance of buildings.