Simulation technique for service life assessment of façade refurbishment

The EU Research Project SUSREF proposes as its outcome sustainable concepts and technologies for the refurbishment of building facades and external walls. One of the tasks in the SUSREF project was to predict the performance and service life of the proposed refurbishment concepts. A simulation software developed at VTT in the 1990s was updated and used to evaluate possible degradation in refurbished concrete facades. The software is able to emulate the temperature and moisture content in a cross-section of a sandwich wall and to apply temperature and moisture sensitive degradation models at critical points of the wall throughout its service life. Five different refurbishment concepts of building facades were analyzed for predicting possible moisture and degradation problems. The analyses were conducted in various European climates and with various materials as thermal insulation and outer core. The results show that the risk of mould growth and continued corrosion of reinforcement should be considered when using dense insulation materials, such as expanded polystyrene and polyurethane. The concepts where the original outer core and thermal insulation are replaced by new ones seem to be relatively risk free. In addition, in cold weather countries the risk of frost attack should always be considered with concretes and mortars. The use of dense coatings on original outer core or rendering may increase the mould risk