Coinciding with the start of construction of the new extension of Barcelona airport (El Prat), the Executive Office of the Barcelona Plan (OEPB), depending on Spanish Airports and Air Navigation (AENA), was set up to manage all works related to this extension. The OEPB developed a specific Plan for Acoustic Insulation based on the DIA (Declaration of Environmental Impact, dated 9 January 2002) in order to deal with the acoustic impact of the opening of the third runway, the new joint use of the three runways, the new takeoff and landing patterns, and the significant increase in air traffic that these involve. In March 2005 AENA and the Technical University of Catalonia (UPC) signed a collaboration agreement to develop this Acoustic Insulation Plan. This document details some of the preliminary conclusions of the architectural team relating to the impact of aircraft noise on buildings.