In order to be validated, the computer programs simulating the air flows in multizone buildings need several measured data sets to be compared with. Such a set was measured on the LESO, a mid-sized administrative building. This set contains: a) The permeability coefficients (C,n) of the building obtained by guarded zone pressurization b) Pressure coefficients Cp measured in windtunnel and on the real building c) Tracer gas air flows measurements d) Corresponding weather data for two periods of 10 days on the non inhabited building.