Résumé : A building pipe network system and method of operating a building pipe network inerting system includes providing an inert gas source, at least one of a closed loop water chiller system and a fire protection system. The closed loop water chiller system has a compressor, a condenser, an evaporator, a first pipe network, and a first vent in fluid connection with the first pipe network. The fire protection system has a source of pressurized water, a second pipe network fluidly connected with the source of pressurized water, a sprinkler fluidly connected with the second pipe network, and a second vent in fluid connection with the second pipe network. There is also a first fluid connection between the first pipe network and the nitrogen source, and a second fluid connection between the second pipe network and the nitrogen source. An inert gas source, such as a nitrogen gas source, is connected to at least one of, and preferably all, the present pipe networks. Inert gas is supplied from the inert gas source to the pipe network. Water is supplied to the pipe network thereby substantially filling the pipe network with water and compressing the inert gas in the pipe network.