Papers by Author: Jitka Mohelníková

Abstract: Energy savings led to design requirements for buildings with thermally insulated envelopes. Window glazing with better thermal insulation properties have in many cases reduced transmittance of solar radiation. They decrease solar thermal gains and daylight level in buildings. A study of influence of selected windows on solar gains and daylighting in a reference room is presented in the paper.

Abstract: Daylighting levels in interiors are changed every day since sunrise to sunset in dependence on luminous exterior conditions. Indoors are illuminated by diffuse skylight prevailing time of the year in Central European counties while a lot of sunny situations occur mainly during transitional and summer periods. The later can produce overheating as well as glare or disturbing luminance due to excessive sunlight in the space close to windows. If interiors are designed with screened work places the influence of direct sunlight during working time has to be evaluated.The article will present results of computer daylight simulations in a side-lit office room oriented to cardinal points. The study is focused on daylighting evaluation of the room orientation influence on levels under clear sky conditions and compared with results achieved for the CIE overcast sky model. The calculations were run in software Daylight Visualizer 2.6.7. The daylight simulation show that applying the clear sky model for illumination of oriented rooms, the substantial different illuminances can be resulted compared to outputs from the common overcast sky daylight metrics.

Abstract: Solar control glass has applications for windows and glazed facades in order to modify indoor visual and thermal comfort in buildings. The article presents the results of evaluation study of optical properties of selected types of solar control glasses and foils. The spectral transmittance measurements were used as input data for daylight comparative studies, and the consideration of convenience of selected solar control glasses and foils for windows are summarised on the basis of analysis of optical properties.

Abstract: Glasses reflective in the spectral range of long-wave infrared radiation operate as heat mirrors. These glasses have found wide applications in architecture. Special thin film coatings on glass panes reflect long wave infrared radiation back to building interiors. The reflective thin films limit absorption of infrared radiation within the glass pane and reduce radiation heat losses of glazings. Heat losses of windows could be significantly limited with the coated glasses which are called low-emissivity glazings. The study of materials convenient for infrared reflective coatings, the optimal composition of thin films and their thicknesses is the main topic of the presented paper. The study is based on measurements of spectral characteristics of selected glasses and computer simulations of the thin film composition for applications of window infrared reflective coatings.

Abstract: Electrochromic materials have found practical applications in special devices such as: - systems with controlled transmission (surfaces with regulated radiation-electrochromic glazings), - systems with controlled reflection (electrochromic mirrors with regulated solar reflectance), and - systems with change of color contrast (special electrochromic information displays). This paper deals with electrochromic devices with a controlled transmission. Electrochromic glazings can be described as devices based on electrochromic materials that operate as reversible switching solar control shutters. These special glasses have found application not only for window glazing in hot climatic conditions but they are also recommended for buildings with large glazed shells where overheating and glare effect represent serious problem for daily service and operation.