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The current climate change context raises the demand for reducing energy and environmental impacts while keeping an economic balance and building users' comfort. Thermal insulation solutions are potential allies in ensuring the adequacy of existing buildings for challenging sustainability requirements. In this scenario, silica-aerogel-fibre-based thermal renders are innovative solutions for which integrated approaches still lack information, and they should be compared with benchmark multilayer solutions, such as those based on expanded polystyrene (EPS), extruded polystyrene (XPS), mineral wool (MW), and insulated corkboard (ICB), to evidence their prospective economic, environmental, and energy benefits. This paper quantifies the optimum insulation thicknesses, life cycle savings, payback periods, and environmental impacts of innovative thermal renders compared to conventional thermal insulation materials when applied as a retrofit in existing facade walls. The results show that cost-optimised thermal renders with sisal fibres led to the best overall performance. Higher heating needs led to higher optimum render thicknesses and life cycle savings. With a 0.02 m thickness, aerogel-fibre-based thermal renders outperformed other materials in terms of heating-degree days (HDD) from 1000 °C·day onwards; they can save approximately EUR 60∙m−2, 1000 MJ∙m−2, and 100 kg CO2 eq∙m−2 while presenting a U-value 13% lower throughout their 30-year lifetime when compared with the second-best multilayer solution with XPS. [ABSTRACT FROM AUTHOR]

Highlights • Experimental campaign on industrial and experimental thermal renders. • Formulations with EPS, cork, and several binders and admixtures. • Physical properties at fresh and hardened states. • Standard and non-standard specimens and brick-render models. Abstract Nowadays, there is a concern in getting buildings with reduced environmental impact and improved thermal and energy performance. The need to use new technologies to comply with the thermal requirements has been driven by the regulation for buildings. With this goal in mind, the use of thermal insulation systems on facades has increased. In this context, renders with high thermal insulation performance have recently emerged on the market. This paper discusses the physical characteristics of four industrial thermal renders, comparing with two experimental render mixtures in which sand is replaced by aggregates with thermal insulating properties (EPS and cork) without any additions or admixtures. It is noticed a need to incorporate high ratios of aggregate with thermal characteristics to achieve thermal insulation renders, affecting other physical properties of the renders at both fresh (workability, air content and bulk density) and hardened (water absorption under low pressure, capillary, dry bulk density, open porosity and drying capacity) states. [ABSTRACT FROM AUTHOR]

This paper quantifies green roofs energy savings which is a challenging topic, namely in Mediterranean climate with distinct heating and cooling seasons. The thermal behavior of a green roof case study in Lisbon, Portugal, was assessed through an experimental campaign during heating and cooling periods of the year of 2013. These experimental results were then used to calibrate a building energy simulation in EnergyPlus. After validation, the numerical model was used to compare the energy performance of intensive, semi-intensive and extensive green roofs. The three green roof types lead to similar heating energy needs but extensive green roof solution shows higher cooling energy needs than semi-intensive and intensive ones, of 2.8 and 5.9 times more, respectively. Furthermore, the performance of each type of green roof and different insulation properties was compared to traditional roof solutions. With no thermal insulation, extensive green roofs require 20% less energy use than black roofs and show a similar annual behavior than white roofs. Semi-intensive and intensive green roofs energy use is 60–70% and 45–60% lower than black and white roofs, respectively. Well insulated roofs do not take full advantage of evapotranspiration cooling effects, which is particularly noticeable when comparing with high reflective white roofs. [ABSTRACT FROM AUTHOR]

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]

• 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]