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The widespread application of innovative thermal enhanced façade solutions requires an adequate durability evaluation. The present work intends to assess the durability of a new aerogel cement-based rendering system through the adaptation of different accelerated aging cycles, such as heating–freezing, freeze–thawing, and heat–cold. Several mechanical properties and also capillary and liquid water absorptions were tested for uncoated and coated specimens. A decrease in the mechanical strength, especially after freeze–thaw cycles, was observed. However, the water action promoted the late hydration of the cement paste contributing to the densification of the matrix and, consequently, the increase of the adhesive strength. Additionally, a decrease in the dynamic modulus of elasticity and an increase in the Poisson’s ratio were observed after aging, which indicates a higher capacity of the render to adapt to substrate movements, contributing to a reduction of cracking.

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The increase of the thermal resistance of building envelopes is a result from the growing demand of energy efficiency. Several new materials and systems emerged in recent years as an answer to that growing need. Thermal mortars applied in thermal rendering systems are an example of how the research community and the building industry try to tackle that challenge.A gap in the durability assessment of thermal rendering systems can however be observed. The existing standardization for the durability assessment of mortars does not allow a consistent evaluation of thermal mortars, especially in multilayer systems. As such, the main goal of the present work consists in proposing a durability assessment methodology of thermal mortars applied as multilayer systems. Accelerated ageing cycles, directly applicable to thermal mortars, were developed through numerical simulation, taking into account material properties, climatic conditions and consequent degradation mechanisms to which the system is subjected.A theoretical methodology for the determination of heat-cold cycles that can represent specific climatic conditions was developed. The implementation of the developed accelerated ageing cycles and the obtained experimental results contributed to the definition of a new durability assessment methodology. This methodology defines the accelerated ageing cycles that should be performed in each climate zone, representative of the main degradation mechanisms. One of the major advantages is the temperature adaption of the accelerated ageing cycles to the climatic conditions. The new methodology contributes to the evaluation of new solutions, during their development stage, and to their adequacy for specific climatic conditions.

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Near-infrared (NIR) reflective materials are being developed for mitigating building cooling needs. Their use contributes to broadening the range of colours, responding to the urban aesthetic demand without compromising the building performance. Despite the increase in NIR reflective pigments investigation, there is still a knowledge gap in their applicability, impact, and durability in multilayer finishing coatings of External Thermal Insulation Composite Systems (ETICS). Hence, the main goal of this work consists of evaluating the impact of incorporating NIR reflective pigments (NRP) in the solar reflectance of the surface layer of ETICS, without affecting the colour perception, as well as their influence on the colour durability and surface temperature. As such, colour, solar reflectance, and surface temperature were monitored for 2 years in dark-coloured specimens of ETICS, with and without NRP and a primer layer. It was confirmed that the main contribution of NRP is the increase of solar reflectance and, consequently, the decrease in surface temperature, especially for high exterior temperatures (around 30 ºC). Moreover, these pigments highly increase the NIR reflectance without affecting the visible colour. In addition, they contribute to maintaining the colour characteristics. The application of primer increased the surface temperature, especially for higher exterior temperatures. However, it contributes to a lower colour difference and solar reflectance variation, which is an important achievement for durability purposes.

In this paper, two aerogel-based renders are characterized based on in-situ testing of walls prototypes. The in-situ tests to assess the mechanical performance are: pull-off, surface impact tests and compressive strength on collected samples. The physical performance includes the water resistance and thermal conductivity coefficient. The tests carried out to assess water-resistance are: Karsten tube, moisture meter and capillary water absorption of collected samples. The thermal performance was tested based on infrared thermography and thermal conductivity transient method. The combination of these in-situ tests allowed a better performance characterization of the aerogelbased renders and characterized the applied renders. These results were carried out under two national research projects (Nanorender and P2020 PEP).