The Impact of a Mobile Shading System and a Phase-Change Heat Store on the Thermal Functioning of a Transparent Building Partition

Abstract

The article presents the results of multi-month field tests and numerical analyses describing the thermal functioning of mobile shading systems for building windows containing a phase-change heat accumulator. The experiments were conducted in the summer period with temperate climate conditions in Rzeszów (Poland). The tested shading system was dedicated to the daily life cycle of residents, taking into account both the need to illuminate the rooms with natural light and reducing the undesirable overheating of the rooms in the summer. The obtained empirical results showed a reduction in room overheating in the summer period by 29.4% from composite windows with a phase-change heat accumulator and a mobile shading system as compared to the reference composite window with an analogous mobile shading system. The database of empirical results allowed for the creation and verification of a numerical model of heat conversion, storage and distribution within the composite window containing phase change material and a mobile shading system. The verified model made it possible to analyse the thermal functioning of the modified transparent partitions in cool temperate, temperate and subtropical climates. The article is a solution to the problem of undesirable overheating of transparent building partitions by efficient storage and distribution of solar radiation energy thanks to the use of a mobile shading system and a phase change material, while presenting a useful tool enabling the prediction of energy gains in different climatic conditions.

Functioning of Heat Accumulating Composites of Carbon Recyclate and Phase Change Material

“…In order to verify the obtained functions of the object in the form of the approximating polynomial, the null hypothesis condition was checked according to Equations (10)–(14) of the Fisher–Snedecor test. The test was carried out by comparing the variance values of the separated empirical results obtained during the research and the variance of the values calculated in accordance with the approximating function formulas presented in Table 3 .The analysis of the matching of empirical to theoretical values was performed using the quasi-Newton method, as in the works [ 5 , 7 , 37 ]. The determination of the minimum of the error function was performed in accordance with Equation (15).…”

“…Obtaining an a d value greater than the additionally calculated error amount a dmax makes the model adequate. The methods of determining the function approximation error most frequently quoted in the literature [ 5 , 7 , 40 , 42 ] are: Maximum absolute approximation error; Maximum relative error; Mean square error. …”

“…Phase change materials, according to the works [ 2 , 4 , 5 ], are characterized by isothermal absorption, storage, and release of thermal energy in the temperature range of phase transformations. In cooperation with building components, according to the works [ 4 , 5 , 6 , 7 , 8 ], phase change materials are mainly used with melting/freezing points in the range of 18–30 °C, where they have the highest possible enthalpy of phase change. According to the works [ 3 , 4 , 5 ], in construction, organic compounds or their mixtures (saturated hydrocarbons, alcohols, carboxylic acids, esters, and some polymers) are most commonly used as PCM..…”

“…The modeling of heat flows within phase change materials during their aggregate state transformation is possible by using finite difference method equations in the overt system [ 5 , 7 , 37 ] and finite element method equations [ 38 ]. On the other hand, in the case of experiments, the nature of which makes it impossible to perform many experiments, the determination of the influence of individual input quantities on the value of the output expression can be obtained without determining the form of the approximating function using artificial neural networks using the Mamdani–Assilian method, as in paper [ 39 ].…”

Comprehensive Risk Management in Passive Buildings Projects

“…Its application contributes to better thermal performance properties of the whole building, reducing heating and cooling costs. In [45], a mobile shading system with a phase-change heat store aiming to illuminate the rooms with natural light and reduce the unwanted overheating of the rooms was tested. A depletion in room overheating in the summer of 29.4% was reached.…”