Various embodiments of the teachings herein include methods and systems for providing a speech-based service for the control of room control elements in buildings. Speech instructions are received by means of an audio device. The audio device is configured to analyze the received speech instructions, to convert them into corresponding operating commands for room control elements for the control of, in particular, HVAC devices (e.g. field devices) in a building and to pass them on to the corresponding room control elements. Before the receipt of the speech instructions by the audio device, the identity of the sender (user) of the speech instructions is anonymized by means of an anonymization service.