Milan Ostrý

Application of Phase Change Materials to Reduce the Risk of Overheating of Building Interior

People in the developed world require comfortable indoor climatic conditions. In the summer time there is often risk of the overheating of buildings, especially buildings with lightweight envelope. Requirements for interior temperature are not summarized in one piece of legislation, but parameters of indoor environment are set according to the type of using of internal space by various laws, regulations, standards and other regulations. Passive cooling can maintain a state of indoor environment in the required temperature range in accordance with legislative framework. Presented system uses phase change materials as a latent heat storage medium for better absorption of heat. The tested system combines the latent heat storage material in the form of micro pellets, which are dispersed in the gypsum plaster, and capillary cooling for their activation so that the secondary effect is possibility of a direct radiant cooling of the room.

Impact of Hydrophobic Additives on Properties of Clay Plaster

Use of clay plasters in the exterior forces owners to conduct frequent maintenance of the plaster’s surface, which may be damaged by the weather. This paper describes partial results of the research, which strives to develop cost-efficient hydrophobic additives to increase service life of exterior clay plasters. We have chosen 7 hydrophobic materials and added them to the reference prefabricated plaster mixture. Samples of the enhanced plaster were tested to evaluate the additives’ impact on the overall mechanical, thermal and moisture characteristics of the plaster. Long-term testing of the best hydrophobic additives will follow to verify their properties in real buildings. Clay plasters play a significant role for the healthy indoor climate due to the influence on the stability of the indoor temperature and humidity.

Simulation of Summer Thermal Stability and Comparison with Measurement

Thermal stability of the indoor environment in summer period is influenced by the local characteristics of the building site, building geometry, orientation of glazing, heat storage capacity of structures, method and intensity of ventilation, but also the size and characteristics of transparent surfaces and associated heat gains from sunlight. The intensity of solar radiation is a very important parameter that affects the temperature in the room. As a boundary condition in computer simulations is used “Reference climatic year”, but the values are more or less different from the actual measured data. This article presents a comparison of the dynamic calculation of the temperature in the room with the real measured values. In addition, the calculation is modified by substitution of actually measured climate data.

Compare of Experimental and Numerical Evaluation of Structure with Application of Reflective Insulation

Thermal insulation effect of reflective insulation is based on the reflection of thermal radiation. Reflective insulations are mainly used in combination with the non-ventilated air cavity. Proposed paper deals with experimental measurements of the thermal insulation properties of the air cavity surrounded by low-emissivity surfaces and comparison of measured values with calculated values according to the standardized procedures. The beginning for determination of the thermal resistance of air cavity was to conduct several experimental measurements by Hot Box method using heat flow meter. The results show good agreement between measured and calculated data.

The Impact of the Choice of Computational Methods on the Results of Simulations of Specific Heat Consumption for Heating a Family House

There are almost 100 passive houses registered in the Czech Republic, whose design was influenced by simulations coming from various design software from early stages with maximization of energy savings in mind. The accuracy of the simulations however, depends on the level of simplification and accuracy of inputs, such as climatic data, etc. Especially the energy simulations require databases with hourly or monthly climatic data. The questions are, whether these are corresponding with reality and to what extend the difference between the database data and reality will affect the simulations and subsequently the use of the houses.This paper deals with modelling of and energy-efficient house under several sets of climatic data. The analysis was done in monthly steps using Energie 2013 (methodology of ČSN EN ISO 13790:2009) and PHPP 2007 software tools and in hourly steps on the basis of reference data of a climatic year described in ČSN EN ISO 15927-4:2011 (TRNSYS) and from the database of Meteonorm (TRNSYS). The aim of this paper is to point out the differences in the determination of heat consumption using different calculation methods..

Calculation and Experimental Evaluation of the Thermal Resistance of a Structure with Reflective Insulation

As reason of increasing requirements of thermal insulation properties of the exposed envelope, reflective insulation are among kind of modern thermal insulation materials ones, which can significantly increased thermal insulation performance if their application is correct. Thermal insulation performance is caused by reduction of the heat transfer by radiation. Conjunction of low-emissivity surface of the reflective insulation and air layer is important to account. This article is focused on the determination of thermal properties of reflective insulation and the results of measured values thermal resistance of determination by hot box method using heat flow meter are presented here. As part of determination of thermal properties of reflective insulation by experimental methods, the test element used to measure the thermal resistance of an insulated air cavity had to be created for concordance with the normative requirements. The part of this article is determination of the thermal resistance by the calculation of derived physical relations and comparison with values of the laboratory measurement.

Thermal Stability of Attic Spaces with Integrated PCMs during the Climatic Year

This paper deals with the impact of using phase change materials (PCM) in light building constructions. It describes how these materials react during the whole year, how they impact the summer temperature stability of a room and how they react in the transition period and in the heating period. Measuring was carried out in the experimental and reference room in the attic of the Institute of Building Structures. The layout of these identical rooms enables to compare the measured values. The measuring of the indoor climate, which had been carried out during the whole year in the reference and experimental room, was analyzed. The analysis was used to create the basic methodological procedure for using PCM in light building constructions. These materials proved to be efficient in the summer time. During the heating period the power consumption was monitored in relation to the application of the phase change materials.