A method for automatically configuring a network address of network interfaces of communicating elements (6, 8, 10, 22, 24) which are intended to form part of a home automation system for a building and belonging to an unconfigured network part, the unconfigured network part including a head network equipment item (22, 24) and at least one communicating element (6, 8, 10, 22, 24), the network address of each network interface including a network prefix, the method being implemented subsequent to the connection of the head network equipment item (22, 24) to a configured communication network belonging to the home automation system for a building, the communication network being arranged in the form of a hierarchical network including at least two successive hierarchy levels, the method comprising the steps of: - negotiating (72, 80) the network prefix of the network interface of the head network equipment item (22, 24), - propagating (74, 82) said network prefix to the communicating elements (6, 8, 10, 22, 24) belonging to the network part with a view to the automatic configuration of the network addresses of the set of network interfaces of said communicating elements, the propagating of the network prefix comprises the sending, by the network interface of the head network equipment item (22, 24) and to at least one first network equipment item (22, 24) directly connected to the head network equipment item (22, 24), of the network prefix of the network address of the network interface of the head network equipment item, and the method including steps for: - negotiating a network prefix of the network interface of the first network equipment item (22, 24) from the network prefix received from the head network equipment item, - advertising the network prefix of the network interface of the first network equipment item, to communicating elements (6, 8, 10, 22, 24) directly connected to the first network equipment item, - if the recipient communicating element (6, 8, 10, 22, 24) is a network equipment item (22, 24), the steps for negotiating (78, 80) and advertising are repeated in a cascade for each network equipment item of successive hierarchy level, in a descending order. the unconfigured network part including a head network equipment item (22, 24) and at least one communicating element (6, 8, 10, 22, 24), the network address of each network interface including a network prefix, the method being implemented subsequent to the connection of the head network equipment item (22, 24) to a configured communication network belonging to the home automation system for a building, the communication network being arranged in the form of a hierarchical network including at least two successive hierarchy levels, the method comprising the steps of: - negotiating (72, 80) the network prefix of the network interface of the head network equipment item (22, 24), - propagating (74, 82) said network prefix to the communicating elements (6, 8, 10, 22, 24) belonging to the network part with a view to the automatic configuration of the network addresses of the set of network interfaces of said communicating elements, the propagating of the network prefix comprises the sending, by the network interface of the head network equipment item (22, 24) and to at least one first network equipment item (22, 24) directly connected to the head network equipment item (22, 24), of the network prefix of the network address of the network interface of the head network equipment item, and - negotiating (72, 80) the network prefix of the network interface of the head network equipment item (22, 24), - propagating (74, 82) said network prefix to the communicating elements (6, 8, 10, 22, 24) belonging to the network part with a view to the automatic configuration of the network addresses of the set of network interfaces of said communicating elements, the propagating of the network prefix comprises the sending, by the network interface of the head network equipment item (22, 24) and to at least one first network equipment item (22, 24) directly connected to the head network equipment item (22, 24), of the network prefix of the network address of the network interface of the head network equipment item, and - negotiating a network prefix of the network interface of the first network equipment item (22, 24) from the network prefix received from the head network equipment item, - advertising the network prefix of the network interface of the first network equipment item, to communicating elements (6, 8, 10, 22, 24) directly connected to the first network equipment item, - if the recipient communicating element (6, 8, 10, 22, 24) is a network equipment item (22, 24), the steps for negotiating (78, 80) and advertising are repeated in a cascade for each network equipment item of successive hierarchy level, in a descending order.