This document applies to the design of ventilation and room conditioning systems for non-residential build-ings subject to human occupancy. It focuses on the definitions of the various parameters that are relevant for such systems. Naturally ventilated buildings are outside the scope of this document. The classification uses different categories. For some values, examples are given and, for requirements, typical ranges with default values are presented. The default values given in this document shall be used where no other values are specified. Classification should always be appropriate to the type of building and its intended use, and the basis of the classification should be explained if the examples given in the standard are not to be used. National regulations must always be followed, even when they are out of the range given in this document.