Durability of Thermal Insulation Materials Based on Renewable Resources - Determination of Hygrothermal Loads as the Basis to Derive Useful Artificial Test Scenarios

Knowledge about the durability of thermal insulation materials is essential to establish constructions that meet the requirements concerning thermal, moisture and fire protection over the whole lifetime of the building, respectively allows to draw conclusions about necessary maintenance. In the underlying project, the relevant influencing factors and resulting ageing mechanisms (e.g. settlement/shrinkage, changes in the microstructure, degradation of additives, biological processes, etc.), as well as their effect on the essential characteristics (thermal conductivity, mechanical and moisture properties and fire behaviour) are identified for the most important groups of insulating materials made from renewable resources (wood fiber, loose filled cellulosic insulation (LFCI) and hemp). Based on this, suitable scopes of investigation are developed to prove durability for a service life of at least 50 years. This paper shows the results of hygrothermal modelling for a variety of representative constructions and locations all over Europe. To derive potentially useful test scenarios, special focus is given on the evaluation of the frequency distribution of hygrothermal conditions (couples of temperatures and relative humidity) over the lifetime, for the critical parts of the insulation materials. The simulation study evaluates the influence of the location (climate), use scenario (operation), construction and material types (adjacent materials, sorption and liquid transport behaviour etc.). Depending on the evaluation criteria, single hours (failure conditions) or average values over longer periods (development of decay or mould, strengths loss etc.) are considered. Also the ranges or amplitudes could be of relevance. Based on the results, accelerated lab ageing tests will be developed. On this basis, it will be checked in a later step, which scenarios actually lead to a change in properties and performance.