The source of the UL listings named throughout this directory’s fire door, alarm and passive-protection files, and one of the marks most North American fire product schedules are written around. Its 110-acre headquarters campus at Northbrook, Illinois is being rebuilt around a Global Fire Science Center of Excellence — ground broken in August 2025, completion expected mid-2027 — covering commercial and residential sprinklers, pipes, fittings and valves, extinguishers and firefighting foam, exterior walls and perimeter fire barrier systems; a separate Northbrook laboratory runs electric-vehicle battery fire testing. No UK site is listed here, and the reason is worth stating: the Basingstoke laboratory’s UKAS accreditation (5772) covers façade, weather and security testing rather than fire, and the fire resistance laboratory UL Solutions funded at Blockley in 2022 — two furnaces and BS 8414 rigs — is operated by the Fire Protection Association.