Abstract: A computer-implemented control system for generating control signals for controlling one or more remotely-located interaction units via a wide-area communications network is described. The control system comprises: a request interface processor for receiving a request for a control signal of a requested control parameter (RCP) relating to a specified environmental requirement (SER) from one of the one or more remotely-located interaction units; the request including: a current value of the RCP, a specified value of the SER; and current values of one or more local environmental parameters (local CERs) related to the SER.