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Indoor visual comfort is one of the leading requirements for building design. Results of computer daylight simulations serve to optimise the design process. Computer programs Ecotect and Radiance were used for the simulation of daylighting from tubular light guides of various diameters and lengths. The internal illuminance calculations were compared for two extreme situations in boundary conditions -sunny summer sky and winter overcast sky, determined for the climatic region of Central Europe. Daylight simulations give information about indoor illuminance on vertical and horizontal reference planes depending on various dimensions of the light guides. Finally, the assessment of annual variation of average internal illuminance from light guides under different outdoor climatic conditions -for uniformly overcast sky, intermediate sky, clear sky and sunny sky -was completed. The simulation results serve to evaluate daylighting and visual comfort in interiors illuminated from light guides.

Daylighting simulation programs use different methods and algorithms for illuminance calculations in buildings. It is widely known that results of different lighting simulation programs does not have to be the same for two or more identical rooms. Hence CIE issued Technical Report 171: 2006 which presents test cases to assess the accuracy of lighting computer programs. However, these test cases are simple and the accuracy of daylighting computer programs can be different for more complex cases. The purpose of this paper is a comparison of differences in the results computed by various daylighting simulation programs for selected test cases according to CIE 171: 2006 and for more complex cases.

Research and development at Brno University of Technology, Faculty of Civil Engineering is focused on the experimental assessment of modern timber structures. For the assessment of the influence of different timber structures on indoor environment a comparative method is used. This method is based on the measurement of indoor environment parameters in the experimental house. There are 4 test (reference) rooms, each of them having the same geometry but a different light-weight composition of envelope which are flexible at the same time.

Daylight has been used for centuries as the main source of light in the interior and has always been an implicit part of architecture since the buildings existed. Not only does it replace electrical lighting during the day, reducing electric power consumption, but it also affects heating and cooling, making it an important parameter in energy efficient design. Research has shown that daylight is a great asset to health and comfort, so it is crucial for building occupants. Daylighting of the interior spaces of buildings and their functionally defined parts is proposed according to visual activities. The minimum values for daylight factor are set for individual visual activities. This article deals with factors influencing the value of the daylight factor.