• Energy Research

Abstract The role of advanced isothermal heat storage systems in buildings is discussed. A storage system encapsulated with phase change materials in which energy is absorbed in the hot period and released in the cold period is analyzed. The thermal behaviour of isothermal heat storage composites is examined using numerical techniques. Two methods of heat transfer with latent heat storage are described in the first part. Based on the initial results, the “effective heat capacity” method was selected and implemented into ESP-r. Numerical studies on the effect of isothermal storage of solar energy in specific building material components are discussed in the second part. Numerical simulations were conducted for two cases of multi-zone, highly glazed and naturally ventilated passive solar buildings. PCM-impregnated gypsum plasterboard was used as an internal room lining in the first case study and transparent insulation material combined with PCM was applied for the external south-oriented wall in the second case study. The behaviour of a TIM–PCM wall and its influence on the internal surface temperature are estimated. Air, surface and resultant temperatures are compared with a “no-PCM” case for both case studies and the diurnal and the seasonal latent heat storage effect is analyzed.

Currently, there is much discussion about modern technologies and solutions in construction. There are new solutions that save electricity or heat, usually in buildings additionally equipped with intelligent management systems. High hopes are placed on building materials. Every investment begins with them. The basic building materials include materials such as cement, bricks, hollow bricks or plasterboard, and their modification and the use of admixtures ensure the greatest changes in the parameters of the building. This article focuses on the preparation and testing of gypsum mortar consisting of gypsum, phase change material and polymer. The idea was to replace the proven method of adding microencapsulated phase change material by direct binding. This article presents the study of thermal conductivity by the hot wire method. Using this method, tests of temperature changes during plaster hardening were also carried out. Compressive strength tests were also carried out on the 14th, 21st, 28th, 35th and 105th day from the date of making the samples. For each of these tests, three types of samples with different polymer content were used. After a series of tests, the best results were obtained by a series of samples with 0.1% polymer.

The aim of the present work is to refine the ESP-r system by incorporating phase change materials (PCMs) modelling. The behaviour of PCMs is modelled using ESP-r's special materials facility. The effect of phase transition is added to the energy balance equation as a latent heat generation term according to the so-called effective heat capacity method. Numerical simulations were conducted for a multi-zone, highly glazed and naturally ventilated passive solar building. PCM-impregnated gypsum plasterboard was used as an internal room lining. The air, surface and resultant temperatures were compared with the no-PCM case and the diurnal latent heat storage effect was analysed. While this effect did not cause a considerable reduction in the diurnal temperature fluctuation, the PCMs did effectively store solar energy in the transitions periods. Additionally, the energy requirement at the beginning and end of the heating season was estimated and compared with ordinary gypsum wallboard. Within this comparison, the PCM composite solidification temperature was 22 °C (i.e. 2 K higher than the heating set-point for the room). The results show that solar energy stored in the PCM-gypsum panels can reduce the heating energy demand by up to 90% at times during the heating season.

AbstractNowadays, one of the most promising renewable energy technology is based on photovoltaic conversion of solar energy. Application of PV systems integrated with building envelope allows electricity to be utilized on site for any functional needs. Building integrated photovoltaic (BIPV) is commonly used in representative, office buildings usually occupied during the day. The large surface area of external walls or roofs is covered with PV panels instead of traditional building materials. In highly glazed buildings, transparent elements are more often being equipped with PV cells placed between two sheets of glass. Moreover, brand new technologies focus currently on homogenous, transparent glass with different transparency.The main aim of the presented study was to analyse transparent PV (TPV) integrated with office windows. The following 10%, 20% or 30% of transparency degree were considered, depending on the required illuminance inside the room. The optical properties were obtained on the basis of literature review and manufactured data. Different types of TPV were defined for the purpose of building energy performance analysis. Numerical model was developed using control volume method. The properties of TPV glass layer were estimated considering thermo- electrical solar energy conversion, taking into account the sun beam angle and temperature of thepanel.The model of single office room with TPV windowpane was analysed numerically. Results obtained for different TPV panels were compared with traditional clear float double glazing. The following two building energy performance parameters were obtained from numerical analysis: electricity produced by TPV and solar heat gains. Based on simulation results, the overall yearly energy performance was presented and compared.

Abstract The proper designing of PV systems requires the use of advanced building energy simulation techniques. It allows to design the best position of the PV array, as well as the right quantity of produced energy in different cases. On the other hand the PV efficiency is not only a constant value but changes according to temperature and solar radiation. This paper is devoted to estimate the simultaneous effect of both weather factors on PV efficiency. The task was achieved by numerical simulation and ESP-r software. Computer simulations have been carried out with the use of the Typical Meteorological Year data for Warsaw (52°N 21°E). The greatest influence of temperature on the efficiency of solar energy conversion was observed for crystalline silicon cells. The influence of the boundary conditions assumed in the study is ignored for amorphous silicon cells in the summer period and regardless of the material type in the winter period.

Abstract The urban environment is characterised by diverse structures over an area consisting of buildings, greenery and various ground surfaces. The analysis and modelling of the reflected solar radiation distribution phenomenon in such surroundings are very complex. This paper presents a holistic approach to the analysis of reflected solar radiation in an urban environment. The main body of this work is the presentation and validation of a new method for determining solar irradiance reflected from the surrounding urban elements based on a high dynamic range imaging photometric technique and on-site luminous efficacy measurements. In the proposed method, the effect of the following parameters on the reflected solar irradiance is considered: the characteristics of the surrounding environment, the position of the sun, and the sky conditions. Reflected solar irradiance was determined on selected days throughout the year for two cases differing in urban environment characteristics. The evaluated reflected solar irradiance strongly depends on the surrounding environment, the season of the year, sky conditions and the position of the sun. These discrepancies indicate the complex characteristics of reflected solar irradiance. The proposed method has been validated by comparison of the obtained results with the measured value of solar irradiance incident on vertical surfaces. The convergence of the obtained results and the measurements was very high with a coefficient of determination of 0.95.

The main goal of this study is to develop the new external thermal insulation composite system (ETICS) by integration of flexible photovoltaic (FPV) and encapsulated phase change materials (PCM). This work is the first step of the international project En-ActivETICS and concerns mainly material selection and systems integration issues. The paper presents a complete solution of façade component which integrates thermal insulation, heat storage and electricity generation - En-ActivETICS that combines ETICS technology with a self-supporting flexible photovoltaic elements. This system will be applicable for both masonry or concrete constructions and it is a new step in the development of building facade technology allowing to achieve a component classified to the group of functional material. In the paper, the formulation of basic principles of En-ActivETICS as well as an overview of existing materials and technologies is presented. Finally, the initial concept of the system is described. The main features of that system is using an elastic, high heat capacity and frost resistant adhesive joining flexible PV with thermal insulation.