NIRON PP-RCT polypropylene pipes and fittings produced by NUPI Industrie Italiane have been used for the replacement of the steel piping of the air-conditioning system of the Porta Nuova financial district in Milan. Porta Nuova is the new district in Milan hosting the award-winning Bosco Verticale, which incorporates an incredible living green façade. After just a few years, steel pipes showed leakage due to the particular chemical composition of the groundwater. The NIRON polypropylene system is always a viable alternative to steel pipes due to its inertia to any corrosion caused by water and its special chemical composition. For this very reason, the NIRON system was chosen by CEFLA, the contractor company based in Imola, Italy, which looks after the maintenance and management of heating and air-conditioning systems in civil and industrial buildings. NIRON PP-RCT pipes and fittings were chosen for this installation. PP-RCT is a new generation material that represents the evolution of the well-known and consolidated PP-R and a valid alternative when it starts showing some limitation, such as in case of high pressures, especially at high temperatures. Its temperature/pressure performance allows for the use of thinner pipes thus offering a greater flow rate with the same diameter. The advantage of polypropylene pipes lies in the lightness of the pipe which has certainly facilitated the replacement operations. In addition to pipes up to a maximum diameter of 315mm, various special pre-assembled parts were produced in NUPI Industrie Italiane laboratories. The entire system was replaced without causing discomfort to the offices operating within the facilities. All the works were done at night and during the weekend to prevent service interruption to the offices. In addition to elbows and tees, NUPI Industrie Italiane also produced several large manifolds with up to 11-way outputs, made up of diameter 125mm saddle joints welded by polyfusion welding, flanged and then joined to elbows welded by butt fusion. The combined use of butt fusion, socket fusion and electrofusion welding allowed to exploit the system properties to the fullest and to run the works quickly and safely.