Search

There is an increasing demand for highly efficient thermal insulating materials in buildings. This study presents a novel solution incorporating nanomaterials, such as silica aerogel, which can achieve low thermal conductivity values (below 0.030 W m−1 K−1) in renders. A key challenge of using aerogels is their low mechanical strength and high capillary water absorption. Here we describe a novel approach employing fibres which mitigates against some key properties which are decreased as a consequence of using aerogel. The incorporation of aramid (0.50%), sisal (0.10%), and biomass (0.10%) fibres (by total volume) was evaluated experimentally in terms of physical, mechanical, and microstructural properties. A synergistic effect between the fibres and aerogel increased mechanical resistance and a reduction in the capillary water absorption, when compared to the reference render (without fibres), whilst maintaining the low thermal conductivity. However, these properties depended significantly on whether the fibres were synthetic or organic. This study is important as it demonstrates that aerogel-based fibre-enhanced thermal renders can contribute to higher energy efficiency in both new construction and retrofitting. The use of these materials will have a direct positive impact on addressing the climate crisis. [ABSTRACT FROM AUTHOR]

[Display omitted] • The new aerogel-based render presents a low thermal conductivity (0.029 W/m.°C). • The thermal conductivity of the aerogel-based render increases with moisture content. • The coating contributes to reducing the hygrothermal risk due to its low capillary absorption. • Hygrothermal risks of aerogel based-renders increase in colder climates. Silica-aerogel is one of the nanomaterials that contributes to increasing the thermal properties, due to its high porosity and low density, and also low thermal conductivity. The development of innovative thermal renderings is a current trend, but their impact on the hygrothermal performance of façade systems requires additional investigation. The main goal of the present work consists of discussing the hygrothermal performance of a new thermal aerogel-based render when applied as a component of a multilayer coating system. To achieve this objective, relevant hygrothermal properties were determined. An accurate analysis of the hygrothermal impact, considering different European climates, was also performed. A clear improvement of the thermal conductivity of the new render, at dry-state, (0.029 W/m.°C) was found. As the observed high open porosity (≈83%) leads to a high capillary absorption coefficient (0.129 kg/m2.s1/2), the prevention of moisture-related risks is a critical issue. Due to the high increase of the thermal conductivity (up to 400%), when saturated, the application of finishing materials is therefore decisive for the successful use of these renders in building envelopes. The numerical simulations highlighted significant hygrothermal risks at higher latitudes, observed by relevant temperature differences across the render thickness and significant external condensation potential. [ABSTRACT FROM AUTHOR]

• Assessment of water resistance, mould susceptibility and surface properties of ETICS. • Moisture content influence on the thermal conductivity of the insulation layer. • Definition of ETICS performance parameters. • Contribution towards the development of ETICS with improved durability. The use of External Thermal Insulation Composite Systems (ETICS) significantly increased in the last decades due to their enhanced thermal properties, low installation cost and ease of application, not only in new constructions but also for thermal retrofitting of building facades. These multilayer rendering systems are constantly exposed to weathering agents and anthropic factors which can lead to physical-mechanical and aesthetical anomalies and thus affect their durability. However, possible synergetic effects among these agents are often neglected by international technical documents on the evaluation of the effectiveness and durability of ETICS. With the aim of filling this gap, moisture transport properties (capillary water absorption, water vapor permeability, water absorption under low pressure, and drying kinetics), thermal conductivity, mould susceptibility and surface properties (color, gloss, and roughness) of twelve commercially available ETICS were assessed and discussed. Possible links between these factors were analyzed and ETICS performance parameters were defined. Results demonstrate that a deeper knowledge of the correlation among ETICS properties can effectively contribute to the evaluation of the efficiency and long-term durability of these systems. [ABSTRACT FROM AUTHOR]