Ventilated Facade Research Articles

A Fast-Calibrated Computational Fluid Dynamic Model for Timber–Concrete Composite Ventilated Façades

Timber–concrete composite (TCC) systems join the positive aspects of engineered wood products (good seismftaic behaviour, low thermal conductivity, environmental sustainability, good behaviour under fire if appropriately designed) with those of concrete (high thermal inertia, durability, excellent fire resistance). TCC facades are typically composed of an internal insulated timber-frame wall and an external concrete slab, separated by a ventilated air cavity. However, there is very limited knowledge concerning the performance of TCC facades, especially concerning their thermal behaviour. The present paper deals with the development and optimization of a 2D Computational Fluid Dynamic (CFD) model for the analysis of TCC ventilated façades’ thermal behaviour. The model is calibrated and validated against experimental data collected during the annual monitoring of a real TCC ventilated envelope in the north of Italy. Also, a new solver algorithm is developed to significantly speed up the simulation (i.e., 45 times faster simulation at an error below 3.5 °C compared to a typical CFD solver). The final model can be used for the time-efficient analysis (simulation time of approximately 23 min for a full day in real-time) and the optimization of the thermal performance of TCC ventilated facades, as well as other ventilated facades with external massive cladding. Our simulation strategy partially avoids the expensive and time-consuming construction of mock-ups, or the use of comparably slow (conventional) CFD solvers that are less suitable for optimization studies.

Thermal Performance Analysis and Design Evolution of Ventilated Stone Facades: A Case Study of the Praski Student House (Akademik Praski) in Warsaw

The rationale for this work arose from the urgency of improving the energy efficiency of buildings at the design stage, given the changing requirements of energy efficiency standards such as the Polish Technical Conditions (WT 2014 and WT 2020). This research is novel as there is currently limited information available on the improvement of the thermal performance of ventilated stone facade systems, although they are now widely used due to their practical and aesthetic advantages. The first objective of this work is to evaluate the thermal performance of the ventilated facades of the Praski Student House (Akademik Praski) and to assess how certain design variations can help achieve a lower level of energy consumption. Using a comprehensive case study approach, this study provides accurate thermal calculations of the facade to assess its global thermal insulation coefficient (Rt) and thermal transmittance (Uc). The improvement in the actual U-value from the original design is as follows: the U-value is reduced from 0.33 originally to 0.228 for WT 2014 and to 0.198 for WT 2020, showing a reduction of about 30.9% and 13.2%, respectively. These results indicate the energy efficiency of increased insulation thickness and optimally oriented air gap dimensions. The practical contributions of this research are valuable for architects, engineers, and contractors involved in the design and construction process of buildings aiming to achieve near-zero energy buildings (nZEBs), including concrete suggestions on how to improve current construction practices as well as material recommendations. There is a need for durability studies, for example to assess the performance of such facades under different climatic conditions, as part of future work to support these findings.

INVESTIGATION OF THE INFLUENCE OF CHOOSING THE TYPE OF FACADE SYSTEM USING ABC ANALYSIS ON THE COST OF THE LIFE CYCLE OF THE BUILDING OBJECT

The article is devoted to a comprehensive study of the influence of the choice of the type of facade systems on the total cost of the life cycle of the construction object, with a special emphasis on the application of ABC-analysis as a tool for determining the optimal option for arranging the facade, taking into account economic and quality aspects. The main purpose of the article is to justify the feasibility of using ABC analysis to select the type of facade systems and assess its impact on the costs associated with the life cycle of the building. The article provides a detailed analysis of various types of facade systems from the point of view of their fastening, materials, design and method implementation. Such systems as ventilated and non-ventilated facades, hinged ventilated facade systems, facades with cladding made of natural stone, composite materials and other modern materials are considered. Special attention is paid to the study of technological characteristics, durability and maintenance costs of various types of facade systems. The application of ABC analysis allows classifying facade systems according to their impact on the cost and quality of construction. In this context, facade systems are divided into three categories: A - the most important and expensive, B - medium importance and expensive, C - less important and with minimal expenses. This approach allows builders and designers to focus their attention on the most critical elements that affect the overall cost and efficiency of construction.As a result of the study, it becomes possible to make an informed decision regarding the choice of the optimal facade system, which best meets the specific needs of the project and contributes to the optimization of the cost of the life cycle of the building. In particular, the selection of appropriate materials and technologies allows to reduce construction costs, ensure durability and reduce maintenance and repair costs in the future. In addition, the results of the study can become the basis for the development of practical recommendations for professionals in the construction industry, including builders, designers and architects. This makes it possible to create more efficient, economical and ecologically sustainable construction objects. Also, the article emphasizes the importance of creating specialist training schools and conditions for the successful implementation of life cycle assessment technologies in the construction industry.

Towards a bio-inspired design of a photovoltaic facade

Facing the challenges of climate change, energy sovereignty and urban densification, operation of local resources and available areas remains an important issue. Integration of photovoltaic components on building envelope is therefore an essential solution to produce manage energy flexibility and obtain Nearly Zero Energy Building. In order to optimize permanently their electrical and thermal performances facing building needs, photovoltaic facades functionalities should adapt and evolve with weather conditions. Bio-inspired design is a breakthrough approach to provide adaptability to physical, mechanical and optical properties of photovoltaic envelope. Therefore, this paper presents the thermal modelling and numerical parametric studies in the case of a photovoltaic bifacial ventilated facade realized with the purpose to identify properties that should acquire adaptive features. Physics related to the identified parameters allow paving the way for the search and the selection of suitable biological adaptive mechanisms. The results of this study indicate that radiative and optical properties of the photovoltaic ventilated facade are the most influential and conflict-inducing parameters on both its electrical and thermal performances. Thus, to provide adaptability to those properties, biological search should be led on live species dealing with extreme heat and radiation and developing adaptive functions aiming to control solar radiation intake.

ВЛИЯНИЕ ОТКАЗА РАБОТЫ ОБЛИЦОВОЧНЫХ ПАНЕЛЕЙ НА ТЕПЛОТЕХНИЧЕСКИЕ СВОЙСТВА НАВЕСНЫХ ВЕНТИЛИРУЕМЫХ ФАСАДНЫХ КОНСТРУКЦИЙ

Abstract. One of the most common solutions for external enclosing wall structures are hinged ventilated façade structures, which, thanks to the use of air layers, provide increased energy efficiency. However, such systems have a number of drawbacks, including the formation of cold bridges in the places of attachment of facade panels, which can lead to significant problems in the operation of the system. In addition, it is known that individual facade panels can fall and refuse to work, which leads to a violation of the closure of the air layer and negatively affects the thermal properties of the structure. Therefore, it is necessary to take into account both the shortcomings of the facade structure itself and the problems associated with its operation in order to correctly assess the impact of the failure of the facade panels on the thermal properties of the structure as a whole. This problem is one of the most important for systems of hinged ventilated facades, as it can lead to a complete loss of thermal engineering properties of the structure. This study considers a theoretical solution to the problem of calculating the heat transfer resistance of air layers in hinged ventilated facade structures and organizing this solution into a consistent design methodology for further investigation of the effect of the fall of facing panels on thermal engineering properties of hinged ventilated facades. The main question of the study, consisting in assessing the impact of the failure of the cladding panels on the thermal properties of hinged ventilated facade structures, is considered in accordance with the provisions of the developed methodology and its subsequent mathematical analysis. The need for such a study is justified by the need to determinethe most effective ways to eliminate the shortcomings of hinged ventilated facade structures and increase their thermal properties.
 Materials and methods: analysis of scientific and technical literature, mathematical analysis of the dependence of the resistance to heat transfer of air layers on the geometric parameters of the structure.
 Subject of research: air layers in hinged ventilated façade structures.
 Results: mathematical dependences are obtained that allow us to estimate the change in the moisture content of the thermal insulation material of hinged facade systems, the air velocity in the air layer and the air temperature in the air layer because of facing panel’s failure. 
 Conclusions: failure of facing panels of hinged facade systems leads to a change in the humidity of the thermal insulation and the parameters of the air layer, which can lead to exceeding regulatory requirements.

Parametric energy optimization of a ventilated facade with windows in Mediterranean climates

Ventilated facades are an effective passive measure to improve the energy performance of buildings in warm and temperate climates such as the Mediterranean. However, although in the Mediterranean sociocultural context the use of windows is widespread, there is a lack of energy analysis of ventilated facades in combination with windows. This is due to the lack of accurate simulation tools to evaluate the energy performance of this combination because of its complex thermodynamics, which, among other issues, requires three-dimensional computational fluid dynamic tools. In this work, a parametric energy analysis of the design parameters of a ventilated façade with window openings has been performed using a three-dimensional numerical model developed by the authors that combines turbulent Navier–Stokes thermodynamic equations for air with a set of differential equations for the envelope temperatures. The results of the analysis showed the potential of the opaque ventilated façade (OVF) with windows when applied to the rehabilitation of energetically obsolete facades, achieving a remarkable reduction in heat flux with respect to these facades, a reduction that reaches 32% for the yearly heat flux when using the optimal configuration found.

Conceptual design and preliminary experimental study on curved PV ventilated facade assisted heat pump system (CPVF-HP)

Integrating photovoltaic PV with curved architecture boosts renewable energy use and reduces carbon emissions in building applications. This paper proposes a curved PV ventilated facade assisted heat pump system (CPVF-HP), utilizing curved PV ventilation facade as carrier for the application of PV in curved buildings, and enhancing overall energy efficiency through synergistic operation with heat pumps. In the cooling mode, the system employs the heat pump evaporator to pre-cool the air entering the curved PV ventilated facade, thereby reducing the temperature of the PV cells and the air conditioning load of the building. In the heating mode, the CPVF-HP system preheats the air entering the heat pump evaporator using the curved PV ventilated facade, elevating the evaporation temperature of the heat pump. The experimental setup of CPVF-HP is established, and the dynamic performance of the CPVF under various ventilation conditions and its synergistic operational performance with the heat pump have been investigated. The results indicate that CPVF displays considerable difference in irradiance and temperature across its east–west orientation, especially noticeable during morning and afternoon hours, affecting the system's electrical performance. Notably, isotropic scattered radiation improves radiation uniformity and the electrical efficiency of CPVF. The system achieves a notable average electrical efficiency increase of 69.90% on cloudy days compared to sunny conditions. CPVF-HP system effectively manages temperatures by precooling or preheating the air, enhancing the electrical efficiency by 34.43% in cooling mode, and increasing COP by 5.23% in heating mode compared to an independent heat pump operation. The CPVF-HP system demonstrates a synergistic improvement in both thermal and electrical performance, offering an innovative approach to optimizing energy efficiency in curved PV integrated buildings.

Application of the Finite Element Method in Determining the Reduced Heat Transfer Resistance of a Hinged Facade System in Residential Buildings

In this paper, the energy efficiency of a ventilated facade is considered by calculating the reduced heat transfer resistance of a hinged facade system (HFS). We have approved three options for fixing the hinged ventilated facade to three types of walls of residential buildings based on the material of: monolithic reinforced concrete, aerated concrete blocks, and solid brick masonry. The choice of these wall filling materials is due to their wide application, both in new construction and in the reconstruction of existing residential buildings, both in mass development and in private housing construction. The thickness of the insulation is also selected. For the selection of insulation, and in general for the calculation of the enclosing structure, the most important factor is the appearance of a dew point. The dew point depends on the thickness and material of the wall filling, the heat and humidity regime inside the building, and climatic conditions. In this paper, research is carried out in terms of calculating the reduced heat transfer resistance of suspended ventilated facades, taking into account in homogeneities using the finite element method, as well as using the traditional method, taking into account the above factors. A comparison of these calculation methods is made and a conclusion is drawn about the expediency of taking into account point bridges of cold. Through cold bridges, energy losses occur, which leads to a change in the temperature regime in the rooms (temperature decrease) during the cold period of the year, and vice versa, to increased heating of the room during the warm period of the year, which leads to the appearance of a dew point in the wall. On a ventilated facade, the most vulnerable point is the brackets, which belong to the group of point bridges of cold. Based on the calculation results, the best wall filling was determined, which reduces the thickness of the insulation from 30 % to 50 % and reduces the specific weight of the wall structure by 1.25–2.1 times, which significantly affects the load on the building foundation.

Overall performance investigation of a CdTe double-skin ventilated facade integrated with a thermal catalytic air-type PV/T in heating and cooling seasons

To reduce building energy consumption and improve indoor air quality, this paper proposes a CdTe PV double-skin ventilated facade integrated with a thermal-catalytic air type PV/T (PV-DSF-TCPV/T). The mathematical model of the proposed system was developed and validated against the experimental data. The daily and seasonal overall performances of the proposed system, including the electrical, thermal, and formaldehyde degradation performances, were studied and compared with that of a conventional PV-DSF. Moreover, parametric analysis was conducted. The main results are: (1) The annual electricity outputs of the proposed system and the conventional system were 414.88 kWh and 105.88 kWh, respectively. (2) Compared with the conventional PV-DSF, the heating and cooling loads of the proposed system decreased by 10.85 % and 34.86 %, respectively, due to the reduction of indoor heat gain in summers and the increase of it in winters. (3) The daily formaldehyde conversion ratio and CADR were 30.84 % and 67.86 m3/h (4) The volumetric flow rate and the cell coverage of the PV-DSF both exerted obvious impacts on the proposed system.

Comparative summer thermal performance analysis between open ventilated facade and modular living wall

In recent years, passive solutions for building envelopes have become much more common due to their capacity to decrease the heat flux through the envelope during summer time. Vertical greenery systems (VGS) are emerging as an interesting method of decreasing the thermal demand of cities, and also improving the quality of urban life. Open ventilated facades (OVF) have gained popularity due to their capacity to enhance the thermal resistance of the building envelope. As part of a project carried out in a Paslink cell in Vitoria-Gasteiz, an experimental campaign with full-scale VGS and OVF was carried out during the summer season to assess the thermal performance of a modular living wall (MLW) with respect to an OVF. The objective is to demonstrate that a stochastic differential equations (SDE) model can be used to assess the cooling requirements of an MLW and an OVF. An analysis was carried out to evaluate how different characteristics of the main facade affect performance, such as thermal resistance, solar absorption coefficient and convection coefficient. The results of these experiments show that both MLW (46 %) and OVF (67 %) configurations significantly minimize solar heat loads compared to non-passive bare wall (BW) facades, which are the reference configurations.

A comparative life cycle assessment of ETICS and ventilated façade systems with timber cladding

The aim of this work is to evaluate the environmental impact of different solutions for building facade retrofitting. Based on Sustainable Construction, this study is carried out by applying the Life Cycle Assessment (LCA) methodology based on ISO 14044:2006 standard requirements. A “cradle-to-grave” life cycle analysis is developed for each solution, comprising the extraction of raw materials to the disposal phase, and then a comparative analysis was performed by considering the same functional unit: 1 m2 of building facade for a 40-year time horizon. Four retrofit solutions are assessed: two External Thermal Insulation Composite Systems (ETICS), differing only in the insulation material, expanded polystyrene (EPS), and insulation corkboard (ICB); and two ventilated facade systems with different types of timber cladding, thermally modified timber, and painted timber. The data included in the inventory phase is mostly taken from technical documentation and from the Ecoinvent database, complemented with scientific literature and estimations when necessary. The LCA was performed using the SimaPro software applying both EPD (2018) and ReCiPe 2016 Endpoint (H) methods. Results of this study show that, phase-wise, the production and maintenance of the components materials have higher contribution in terms of environmental impact. On the other hand, by comparing the various solutions, the ventilated facade retrofit solution with heat treated timber cladding is the one that shows the highest environmental impact in almost every single category, whereas the cladding solution with painted timber finish is the one that shows the best environmental performance.

Evaluation of the Thermal Performance of Two Passive Facade System Solutions for Sustainable Development

Sustainable development is essential for the future of the planet. Using passive elements, like ventilated facades based on insulation and air chambers, or living walls, which are solutions based on nature, is a powerful strategy for cities to improve their thermal environment, reduce energy consumption, and mitigate the effects of climate change. This approach allows for the quantification of the influence of passive surfaces on energy fluxes compared to bare surfaces. In addition, it delves into understanding how the incorporation of vegetation on building facades alters surface energy fluxes, involving a combination of physical and biochemical processes. This comprehensive investigation seeks to harness the potential of passive and natural solutions to address the pressing challenges of urban sustainability and climate resilience. This research uses a surface energy balance model to analyze the thermal performance of two facades using experimental data from a PASLINK test cell. This study uses the grey box RC model, which links continuous-time ordinary differential equations with discrete measurement data points. This model provides insight into the complex interplay among factors that influence the thermal behavior of building facades, with the goal of comprehensively understanding how ventilated and green facades affect the dynamics of energy flow compared to conventional facades. The initial thermal resistance of the bare facade was 0.75 (°C m2)/W. The introduction of a ventilated facade significantly increased this thermal resistance to 2.47 (°C m2)/W due to the insulating capacity of the air chamber and its insulating layer (1.70 (°C m2)/W). Regarding the modular living wall, it obtained a thermal resistance value of 1.22 (°C m2)/W (this vegetated facade does not have an insulating layer). In this context, the modular living wall proved to be effective in reducing convective energy by 68% compared with the non-green facade. It is crucial to highlight that evapotranspiration was the primary mechanism for energy dissipation in the green facade. The experiments conclusively show that both the modular living wall and open-ventilated facade significantly reduce solar heat loads compared with non-passive bare wall facades, demonstrating their effectiveness in enhancing thermal performance and minimizing heat absorption.

Benefits assessment of cool skin and ventilated cavity skin: Saving energy and mitigating heat and grid stress

This study assessed the energy-saving and climate-adaptive potential of cool skin and ventilated cavity skin facade technologies in Seoul's high-rise apartment buildings. We created weather scenarios for historical, mid-term future, and long-term future conditions using Coordinated Regional Downscaling EXperiment (CORDEX) method. Building energy simulations were conducted on a South Korean high-rise apartment model to evaluate their performance under different weather conditions. The results indicate that cool skin and ventilated cavity skin technologies can save cooling energy during summers but lead to heating energy penalties in winters. Ventilated cavity skin outperforms cool skin, offering better cooling energy savings and reduced heating penalties. Combining both technologies yields the highest overall energy savings, with 7 %, 9 %, and 10 % cooling energy savings for cool skin, ventilated cavity skin, and the combined package, respectively. However, cool skin increases heating energy consumption by 5 %, while ventilated cavity skin has minimal impact on heating energy. These envelope technologies also reduce peak electricity demand by at least 5 %, 8 %, and 9 %, respectively. They contribute to heat stress reduction, enhance resilience, and decrease extreme heat risks for occupants during power outages by at least 18 % under various weather conditions. Considering the prevalence of aging high-rise apartments in South Korea, adopting these envelope renovation strategies can effectively reduce cooling loads, enhance thermal comfort, and boost resilience under future climates, while avoiding costly reconstruction.

РОЗШИРЕННЯ ФУНКЦІОНАЛЬНИХ ВЛАСТИВОСТЕЙ НАВІСНИХ ВЕНТИЛЬОВАНИХ ФАСАДІВ ПРИ УТЕПЛЕННІ БУДІВЕЛЬ

The article shows that a large percentage of the housing stock of Ukraine is represented by panel houses of the mass series of construction in the 1960s-1980s, which were built with understated indicators of the normative requirements for the thermal resistance of the enclosing structures.It is shown that the underestimated indicators of the thermal resistance of the building envelope led to excessive energy consumption per m2 of the outdated housing stock, which exceeds the indicators of the EU countries by 2.0-2.5 times. The construction industry accounts for more than 30-40% of all energy sources for the maintenance of outdated housing.The article compares the growth of the thermal resistance of fencing structures in European countries and Ukraine.An important place in the protection of buildings from the influence of atmospheric phenomena of the environment, their increased energy efficiency and giving a modern appearance to outdated objects is occupied by hinged ventilated facades. Prospects for expanding the functional properties of hinged facades are shown, which provide energy generation due to their cladding with solar panels and energy savings during building cooling due to the installation of textile ventilated facades.

МОДЕЛЮВАННЯ ОРГАНІЗАЦІЙНО-ТЕХНОЛОГІЧНИХ ФАКТОРІВ ДЛЯ ВИЗНАЧЕННЯ ЕФЕКТИВНИХ РІШЕНЬ ПРОЄКТУ УТЕПЛЕННЯ ФАСАДІВ З ОБЛИЦЮВАННЯМ ШТУКАТУРКАМИ

As a result of the research, it was established that in the construction industry, the most widely used systems for insulating external enclosing structures are bonded thermal insulation systems and hinged ventilated facades. It was determined that the technical and economic indicators of the building facade insulation project can be controlled and optimized with the help of preliminary modeling of organizational and technological solutions. Significant organizational and technological factors that have an impact on the technical and economic indicators of the project were determined. The dependence of changes in the indicators of the duration of construction and installation work on insulation, their cost and the intensity of financing when significant factors are varied is revealed. The dependence of the change in the cost of the facade insulation project by the bonded thermal insulation method on the use of various means of underlaying is determined. On the basis of EC-modeling, the dependencies of changes in the cost of the project when using different technological methods and options for organizational solutions for the insulation of external enclosing structures of buildings with plaster decoration were investigated.

Thermal assessment of vertical enclosing structures taking into account thermal effects

Introduction. The hot and unfavorable climate, affecting both the person and the building as a whole, increases more and more every year. This trend of temperature increase is noted not only in the cities of the southern region of the Russian Federation, but also in the world, which is caused by the problem of global warming. Identification of the values of thermal effects on buildings and structures in the aspect of increasing the energy efficiency of buildings is a priority.
 
 Materials and methods. The calculation method is presented in the form of a formulaic mathematical model and a numerical method using a software package. The object of the study is a residential building with a frame system construction and frame scheme. Enclosing structures are made of aerated concrete blocks with the device of wet and ventilated facade.
 
 Results. Qualitative and quantitative results of the study are presented in the form of graphical calculations. The results of the energy audit of enclosing structures under conditions of loading by thermal influences are obtained. Temperature dependences between the surface outside of the envelope and inside are established. Critical temperatures on the surface of enclosing structures outside the room at which unfavorable conditions are observed on the surface inside are determined. Problems in the field of determining the threat of external thermal factors on the enclosing structures taking into account their vulnerable parts in the application of two methods of thermal loads control in the conditions of unsteady heat transfer have been solved.
 
 Conclusions. A calculation procedure using the finite element method by means of a software package under conditions of thermal effects on the enclosing structures has been developed, which allows to predict the temperature shifts on the wall surface inside the room. A comparative analysis of the advantages and disadvantages of the recommended structures used for building envelope design is carried out. The conditions for energy efficiency improvement in the application of two methods of thermal load control under unsteady heat transfer conditions have been identified, and recommendations for improving the energy efficiency of building envelope structures have been developed.

Improving thermal performance of a ventilated tiled roof by using phase change materials

Abstract The adoption of ventilated roofs and facades, as well as the integration of phase change materials (PCMs) in the building envelope, has proved to be effective as a passive cooling technique in reducing the solar heat gain through the building envelope during the summer period, therefore reducing the energy requirement for cooling. Even though much research focused on each of these strategies individually, their combination has not been deeply studied yet. Preliminary numerical studies were carried out on the application of PCMs on a pitched ventilated tiled roof, and the most effective position turned out to be the one suspended in the middle of the above sheathing ventilation (ASV) channel. Based on this conclusion and exploiting an existing mock-up facility, two equivalent pitched ventilated roofs with an air gap of 4 cm were built as coverage of two identical rooms, each one equipped with a fan coil, one with a 0.007-m PCM layer suspended in the middle of the ASV and the other one without. They were then tested under real conditions at the TekneHub Laboratory at the University of Ferrara. The behaviour of the two configurations were compared in terms of temperature, velocity of the air in the ASV, heat flux and energy requirement for cooling, which were monitored through T-type thermocouples, heat flow metre, anemometers and energy metres, respectively. The aim of the research was to validate the numerical results and confirm that the combination of the two strategies allows further improvement of roof performance.

Improving the efficiency of energy efficient ventilated facades

Improving the efficiency of energy efficient ventilated facades

Testing the thermal properties of modern ventilated facade fastening systems

The study reported in this paper investigated a set of building fasteners used in ventilated facades. For the building fasteners actually present in the industrial market the values of the effective thermal conductivity were measured experimentally. These values were used next in numerical simulations run with COMSOL Multiphysics software application. The validation of the simulation model was done in specific additional experimental test. The paper presents a method of determining the effective thermal conductivity coefficient for fasteners with a novel design. Temperature distributions and heat fluxes were determined for different variants of multilayer walls with the fasteners. The calculation of the effective thermal conductivity coefficient for a structural profile is based on the heat balance of the measuring stand. The performed tests show not only an expected reduction in the coefficient value for structures in which stainless steel is used. The results also demonstrate that the fasteners with holes cut out in their structures have significantly lower effective thermal conductivity coefficients than those with solid walls. This effect can be justified by the formation of labyrinth-like narrowings extending the conductive heat flow path in the fastener. As a final result of the experimental tests and the COMSOL simulations the application of the effective thermal conductivity as the new indicator of a thermal effectiveness of building fasteners is proposed in industrial practice. Consequently the design of the building fasteners with various shapes of holes is recommended for improving their insulation features.

The Susceptibility to Salt Fog Degradation of Stone Cladding Materials: A Laboratory Case Study on Two Limestones from Portugal

The evaluation of stone cladding material suitability can be a challenge due to the way that stone physical and mechanical properties, and characteristics such as mineralogy, might influence stone performance as a cladding element in a ventilated facade application. Salts can affect natural stone performance, and one of the experimental methods available to study and predict it is through accelerated aging tests such as salt fog chamber cycles. Aging test results should include the analysis of critical stone physical–mechanical properties to fully understand decay effects. The aim of this study was to reduce the lack of knowledge regarding the implications of salt fog on certain fundamental characteristics of stone cladding requirements, such as elastic properties and flexural strength, because these are particularly important properties for ventilated facade systems. A systematic methodology based on artificial salt fog cycles in a climatic chamber, microscopic analysis, weight measurement, flexural strength, and dynamic elastic modulus was performed on two limestones from Portugal: Moleanos (MO) and Semi-Rijo (SR). This study aims to contribute to improved selection stone methods linked to more sustainable stone facades, and the experimental methodology can be further applied to other stone types, particularly the ones most selected for stone cladding applications near coastal areas. In this work, results of salt fog decay cycles are presented and discussed considering their direct contribution for a better stone-cladding dimensioning process.