Fire safety requirements in England make it mandatory to fit smoke alarms on every habitable floor. The Domestic Technical Handbook, issued by the Building Standard Division, states there should be a smoke alarm in each room frequently used by occupants and in every circulation space (such as hallways and landings), a heat alarm in the kitchen and a carbon monoxide alarm. Although this handbook is for new building standards, the Repairing Standard advises that rented homes should match the standards as closely as possible. Also, since 2007, all alarms must be interlinked and mains powered.