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    A nondestructive indirect approach to long-term wood moisture monitoring based on electrical methods
    (MDPI, 2019-07-24) Slávik, Richard; Čekon, Miroslav; Štefaňák, Jan
    Wood has a long tradition of use as a building material due its properties and availability. However, it is very sensitive to moisture. Wood components of building structures basically require a certain level of moisture protection, and thus moisture monitoring to ensure the serviceability of such components during their whole lifespan while integrated within buildings is relevant to this area. The aim of this study is to investigate two moisture monitoring techniques promoting moisture safety in wood-based buildings (i.e. new structures as well as renovated and protected buildings). The study is focused on the comparison of two electrical methods that can be employed for the nondestructive moisture monitoring of wood components integrated in the structures of buildings. The main principle of the two presented methods of the moisture measurement by electric resistance is based on a simple resistor–capacitor (RC) circuit system improved with ICM7555 chip and integrator circuit using TLC71 amplifier. The RC-circuit is easier to implement thanks to the digital signals of the used chip, whilst the newly presented integration method allows faster measurement at lower moisture contents. A comparative experimental campaign utilizing spruce wood samples is conducted in this relation. Based on the results obtained, both methods can be successfully applied to wood components in buildings for moisture contents above 8%.
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    A non-ventilated solar façade concept based on selective and transparent insulation material integration: an experimental study
    (MDPI AG, 2017-06-08) Čekon, Miroslav; Slávik, Richard
    A new solar façade concept based on transparent insulation and a selective absorber is proposed, tested and compared with conventional insulation and a non-selective type of absorber, respectively. The presented study focuses on an experimental non-ventilated solar type of façade exposed to solar radiation both in the laboratory and in outdoor tests. Due to the high solar absorbance level of the façade, high- and low-emissivity contributions were primarily analysed. All of the implemented materials were contrasted from the thermal and optical point of view. An analysis was made of both thermodynamic and steady state procedures affecting the proposed solar façade concept. Experimental full scale tests on real building components were additionally involved during summer monitoring. An indicator of the temperature response generated by solar radiation exposure demonstrates the outdoor performance of the façade is closely related to overheating phenomena. From the thermal point of view, the proposed transparent insulation and selective absorber concept corresponds to the performance of conventional thermal insulation of identical material thickness; however, the non-selective prototype only provides 50% thermal performance. The results of the solar-based experiments show that with a small-scale experimental prototype, approximately no significant difference is measured when compared with a non-selective absorber type. The only difference was achieved at the maximum of 2.5K, when the lower temperature was obtained in the solar selective concept. At the full-scale outdoor mode, the results indicate a maximum of 3.0K difference, however the lower temperature achieves a non-selective approach. This solar façade can actively contribute to the thermal performance of building components during periods of heating.
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    Polycarbonate Multi-Wall Panels Integrated in Multi-Layer Solar Facade Concepts
    (IOP Publishing, 2018-11-01) Čekon, Miroslav; Struhala, Karel
    Recent technological advances in transparent insulation materials´ (TIMs) production may have opened ways for new integration of these materials in buildings. This paper presents a study analysing several variants of façades incorporating TIMs on solar façade principles. The analysis is based on ongoing long-term full-scale experiments in Brno, Czech Republic. The paper introduces the test platform which is used for evaluation of specific aspects of integrated polycarbonate TIMs. The paper describes the experiment results, especially long-term thermal response and passive solar gain data. These data are applied for analysis of: influence of various polycarbonate-based TIMs on the real performance of the façades; influence of implementation of different solar absorbers on the performance of the proposed facades; effectivity of application of latent thermal energy storage (based on PCMs) as a part of heat accumulation layer and coupling of TIM with prismatic glass to enhance optical selectivity aspect. Presented results demonstrate for example significant influence of the type of solar absorber on the thermal performance of tested solar facades: the difference is up to 35% to 54%. Also the integration of prismatic glass coupled with simple two-wall polycarbonate panel can reduce solar penetration through components at the level comparable with the most complex six-wall panel.
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    Study of Surface Temperature Monitoring in the Field of Buildings
    (Elsevier, 2016-09-01) Slávik, Richard; Čekon, Miroslav
    Surface temperature monitoring and its aspects does have not only a useful merit for thermal analysis of the buildings and their direct or indirect implementation in virtual simulations, however is equally of highly relevant use for the field of building physics as primarily those of more complex analyzing concerning on specific thermal phenomena. The measuring of surface temperatures at the building envelopes by means of well-practiced commercial temperature sensors are typically applied whose attributes can successfully be employed especially for the field of thermal building performance aspects. In addition, besides of their certain own accuracy level and final implementation for instance as an input parameter into the simulation model, typical methods of their final application related to the opaque and transparent building surfaces and their contact and non-contact modes may have the significant influence. The paper presents a representative confrontation of surface temperature monitoring of several temperature sensors as finally compared with the form of their final application on standard vertical building surfaces. Three typical ways of installation are demonstrated on opaque and transparent building component under real climate conditions applying of commercial thermocouples, digital temperature and infrared sensors. Experimental measurement assemblies are proposed and introduced with aim to point out deviating indicators in the presented area. Representative in-situ measurements are performed and final comparability of sensors based on typical methods of their final installation is presented. An obtained result, both at existing and comparing types, demonstrates its application relations to the field of buildings. In spite of that, an additional confrontation based on non-contact regime as compared with contact ones reveals a feasible option directly concerning on building surface temperature measuring.
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    Thermal, Energy and Life Cycle Aspects of a Transparent Insulation Façade: A Case Study
    (IOP Publishing, 2018-11-01) Čekon, Miroslav; Struhala, Karel
    Research and development in the façade engineering field highlights the need for comprehensive system solutions integrating advanced materials and renewable energy use. The real performance of such solutions is highly relevant issue as they can contribute towards the European energy and environment policies: e.g. the implementation of nearly-Zero Energy Buildings required by the Energy Performance of Buildings Directive. Presented study focuses on implementation of Transparent Insulation Materials (TIMs) in a façade concept. The concept is based on sensible use of (renewable) solar energy to reduce the heating demand of buildings. The concept integrates TIMs into a Transparent Insulation Façade (TIF) based on more common ”solar wall” or “Trombe wall” systems. The study presents analysis of thermal, solar energy and environmental performance of the concept on a case study basis. Firstly, thermal analysis based on standard calculation is introduced to describe thermal and solar performance of the concepts. Secondly, energy balance calculations are used to compare the concepts with conventional façade systems. Finally, a Life-Cycle Assessment (LCA) evaluating the environmental impacts of the façade concept is introduced. The results show that the proposed concept performs better in both energy consumption and environmental impacts compared to a common facade with external thermal insulation. The TIF has higher heating energy demand than a common façade, however this is offset by up to 178 kWhm-2a-1 solar heat gains. The difference in environmental impacts (up to 80%) is also in favour of the TIF.