EN 1520 describes the design principles and requirements for safety, serviceability and durability of prefabricated components of lightweight aggregate concrete with open structure and with structural or non-structural reinforcement intended to be used in buildings. The design of the components is based on the limit state concept used in conjunction with partial safety factors. EN 1520 is intended to be used together with Eurocodes EN 1990, EN 1991 and EN 1998. Numerical values for partial safety factors and other reliability parameters are recommended as basic values that provide an acceptable level of reliability. They have been selected assuming that an appropriate level of workmanship and of quality management applies. This European Standard contains values with notes indicating where national choices may be made. Therefore, the National Standard implementing EN 1520 should be used with a national application document containing all Nationally Determined Parameters to be used for the design of prefabricated components of lightweight aggregate concrete with open structure and with structural or non-structural reinforcement to be constructed in the relevant country. The Committee responsible for this standard is NA 005-07-09 AA "Porenbeton und haufwerksporiger Leichtbeton (Sp CEN/TC 177)" ("Autoclaved aerated concrete and lightweight aggregate concrete with open structure (Sp CEN/TC 177)") at DIN.