Daylight availability in a room equipped with PCM window

The increase in building energy performance mainly focused on the improvement of physical properties (thermal and optical) of individual components of building envelope. Very good isolation parameters can be easily achieved for opaque elements like walls and roofs. However, improvement of glazed component parameters is still required. Improving thermophysical properties of window can be achieved using phase change material (PCM). Presented work is a part of extensive research project including the analysis and experimental investigation of window integrated with PCM layer. This modification changes the thermal properties of glass unit and effects on visible light transmission through the window. The main purpose of the presented work is numerical analysis of the daylight conditions in the office room equipped with PCM window. The research was done for two geometrically identical indoor spaces varying by the window orientations: eastern and western respectively. Simulation was performed using a coupled validated simulation tools: ESP-r and Radiance. First software was used to model analyzed rooms then using second computational environment the illuminance and daylight factors in selected points were determined. Optical data of glazing unit equipped with PCM were appointed experimentally and adjusted to the numerical model. Simulations were carried out for characteristic sky conditions and selected days of year. Assessment of daylight availability in each room was done based on obtained values of illuminance and daylight factor in selected points. Five cases of the triple glazed window were considered: standard one and equipped with PCM layer positioned in the inner or outer cavity in liquid or solid state. Obtained results show that window with PCM in liquid state does not significantly reduce the daylight availability in room regardless the PCM position. However, window with PCM in solid state significantly decrease the light transmission through the window consequent in insufficient daylight conditions in analyzed rooms

Potential of PV Façade for Supplementary Lighting in Winter

AbstractModern office and public buildings have to meet the requirement of zero-emission buildings through high insulation and integration of renewable energy sources on the own premises. The presented paper is devoted to exploring a BIPV facade potential as a source of electricity for supplementary lighting in an office room during winter. Analysis was carried out, for a typical office room with window centrally located in the facade, using simulation tool ESP-r for energy performance and Daysim for daylight luminance distribution calculation. Results indicate that electrical energy generated by BIPV cover supplementary lighting only in the room with south oriented façade

Improvement of bipv efficiency by application of highly reflective surfaces at the building envelope

The use of concentrated solar irradiation for the improvement of electric generation improvement has been implemented on different scales, mainly in photovoltaic systems. High-concentration Fresnel lenses are widely chosen for this approach in large installations, while low-concentration systems are rather applied in medium-low scales. For the latter, the improvement on electric performance was revealed, even when no solar tracking was implemented. The presented work aims to analyse a low-concentration photovoltaic installation by a numerical approach. First, the reflective surfaces were designed geometrically considering the optimal slope determined for each month. Subsequently, different simulation techniques were used separately for prediction of solar irradiation and energy production. Three criteria were selected to analyze power generation: the highest increase in total annual solar irradiance on panels with reflective surfaces, the highest total annual solar irradiance collected, and the optimal slope of panels for the entire year. The increase in energy was found to not exceed 10% in the winter months. Whereas in the spring and summer months the energy improvement is about 15–20%. Moreover, it was observed that the temperature of the proposed concentration photovoltaic system increased significantly, reaching more than 90◦ C, while for traditional PV panels it did not exceed 75◦ C.Fil: Knera, Dominika. Lodz University of Technology; PoloniaFil: Dellicompagni, Pablo Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; ArgentinaFil: Heim, Dariusz. Lodz University of Technology; Poloni

Providing an interior daylight environment through the use of light pipes

The paper presents the effect of using additional daylight illumination of building interiors using tubular skylight systems. Interior illuminance distribution was analysed using a combination of two daylight sources – window and skylight pipes. The results were obtained for cloudy weather conditions. Final remarks concern the effectiveness of supplementary daylighting of interiors using different configurations of light pipes

Dynamics of melting process in phase change material windows determined based on direct light transmission

Detailed analyses of melting processes in phase change material (PCM) glazing units, changes of direct transmittance as well as investigation of refraction index were provided based on laboratory measurements. The main goal of the study was to determine the direct light transmittance versus time under constant solar radiation intensity and stable temperature of the surrounding air. The experiment was conducted on a triple glazed unit with one cavity filled with a paraffin RT21HC as a PCM. The unit was installed in a special holder and exposed to the radiation from an artificial sun. The vertical illuminance was measured by luxmeters and compared with a reference case to determine the direct light transmittance. The transmittance was determined for the whole period of measurements when some specific artefacts were identified and theoretically explained based on values of refractive indexes for paraffins in the solid and liquid state, and for a glass. The melting process of a PCM in a glass unit was identified as a complex one, with interreflections and refraction of light on semi layers characterized by a different physical states (solid, liquid or mushy). These optical phenomena caused nonuniformity in light transmittance, especially when the PCM is in a mushy state. It was revealed that light transmittance versus temperature cannot be treated as a linear function.Fil: Heim, Dariusz. Lodz University of Technology; PoloniaFil: Krempski Smejda, Michael. Lodz University of Technology; PoloniaFil: Dellicompagni, Pablo Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; ArgentinaFil: Knera, Dominika. Lodz University of Technology; PoloniaFil: Wieprzkowicz, Anna. Lodz University of Technology; PoloniaFil: Franco, Ada Judith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Investigaciones en Energía no Convencional. Universidad Nacional de Salta. Facultad de Ciencias Exactas. Departamento de Física. Instituto de Investigaciones en Energía no Convencional; Argentin

Improvement of BIPV Efficiency by Application of Highly Reflective Surfaces at the Building Envelope

The use of concentrated solar irradiation for the improvement of electric generation improvement has been implemented on different scales, mainly in photovoltaic systems. High-concentration Fresnel lenses are widely chosen for this approach in large installations, while low-concentration systems are rather applied in medium-low scales. For the latter, the improvement on electric performance was revealed, even when no solar tracking was implemented. The presented work aims to analyse a low-concentration photovoltaic installation by a numerical approach. First, the reflective surfaces were designed geometrically considering the optimal slope determined for each month. Subsequently, different simulation techniques were used separately for prediction of solar irradiation and energy production. Three criteria were selected to analyze power generation: the highest increase in total annual solar irradiance on panels with reflective surfaces, the highest total annual solar irradiance collected, and the optimal slope of panels for the entire year. The increase in energy was found to not exceed 10% in the winter months. Whereas in the spring and summer months the energy improvement is about 15–20%. Moreover, it was observed that the temperature of the proposed concentration photovoltaic system increased significantly, reaching more than 90 °C, while for traditional PV panels it did not exceed 75 °C

Two methods for modelling of photoelectric conversion in energy analysis of buildings

Nowadays, there is a growing interest in using of renewable energy sources, especially solar energy which can be converted into electricity by photovoltaic panels. In addition to traditional stand-alone photovoltaic systems, more and more new or modernized buildings are equipped with integrated photovoltaic systems (BIPV). The main aim of this paper is to compare two models used to calculate amount of electric power generated by photovoltaic panel. Analysed models were implemented into well-known simulation programs, ESP-r and TRNSYS

Greenery in the urban environment as a nature based solution for thermal stress mitigation

The problem of thermal environment in the city and small urban settlement is described and discussed in the paper. The study was performed for two areas differed in the intensity of development, buildings height and greenery in the nearest surrounding. The results of measurements compared and discussed come from two, local meteorological stations located in both environments. The summer temperature history was compared and analysed using daily maximum, minimum and averaged values. For 85% of analysed days the minimum air temperature in the rural zone was lower than in the regular city area