Checking all the properties in an area with IR, and also checking all basements and gardens? That would be rightly condemned. It sounds like something the gestapo would do. As well as being completely impractical (it would probably cost more than a full census).Using IR to identify beds in sheds has already been used in local authorities for planning enforcement and EPC purposes. Checking shop basements/ warehouses or in fact people's garages for residents would not be an especially intrusive power and is already available to local authority enforcement teams.