Factor method for aluminium windows and curtain walls

Buildings and building components service life are vital information in a design process because most the choices to be made during this pro cess are influenced by life cycle costs or by environmental impacts over the life cycle, i.e. ele ments that are strictly related to the service life of building systems and components. The ISO 15686 stan dard series suggests a way to predict the service life of a building components: the factor m ethod. Estimating the service life a construction products would have in a set of specific in-use con ditions (determined from reference service life dat a after taking into account any differences from the reference in-use conditions) is an error prone process. The error could influence significantly th e estimation if the factor method is applied at the multiplication level, therefore significant researc h on reliability of the factor method to be used fo r specific construction products is required. Aluminium construction products like windows, CE ma rked in accordance to EN 14351-1, or curtain walls, CE marked in accordance to EN 13830, are som e a ong the others in a building, of the most influencing life cycle costs and environmental impa cts and therefore a highly reliable estimated service life for these products is needed. Applying the factor method, stakeholders and manufacturers have been interviewed to define which are the eleme nts most influencing the service life of aluminium windows and curtain walls. The outcomes of this stu dy have been used to create a specific factor method for each family of components under analysis , which can be classified according to ISO 15686-8 as a combined level factor method where the estimated service life may be computed by combining the multiplication and function level for groups of different factor categories. The Factor Method for service life prediction The service life of a building or a building compon ent is strictly related to its durability, i.e. ability of an item to perform a required function under giv en conditions of use and maintenance, until a limiting state is reached [2]. Studies on durability of buildings and buildi ng components are quite recent, maybe the first research product that achie ved fame was the first state of the art report of C IB W80 – RILEM 71 PSL joint working group, “Prediction of service life of building materials and components” [3] published in 1987, while the first available standards on the topic was the British BS 7543 issued on 1992 [4]. Besides these, one of t he most famous documents in the field is the English translation of “Principal guide for service lif planning of buildings” published in 1993 by the Architectural Institute of Japan [5], a short v ersion of the Japanese guide that contains a genera l method for service life prediction based on the eva luation of physical deterioration. In the Principal guide [5], for example, the servic e life of structural steel frame building is computed as: Y = (Yss × Bs × Cs × Ms) + (Ysp × Dp × Bp × Cp × Mp) (1) Where: Yss: Standard service life (years) of steel; Bs: Part of building where the steel element is insta lled;