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.

Shading by surrounding obstacles is one of main parameters which must be considered in building design. The aim of this paper is elaboration of the façade Daylight Factor (Dw) and shading angle problems defined in the Czech Technical Standards (ČSN) - Daylighting in residential buildings ČSN 73 0580. The measure of Dw represents the value of incidental shading by surrounding obstacles. Sometimes in practice are designers dealing with administrative requirements of officials because of not exact specification of conditions in building law and consequently in ČSN. Because of not exact specifications is happening that officials are requiring requisite assessments. Such issue occurs sometimes also in problem of Daylight Factor Dw – it is not exactly determined when is an assessment of Dw necessary. This paper focused on the definitions mentioned in building law and ČSN related to this issue and proposes specific conditions for eventual Dw assessment.

Lighting conditions in buildings are verified by experts on a daily basis. Such verifications may be done at several phases in various ways. In the field of daylighting, it is common to make an assessment within the pre-design and in-design phases of a construction work throughout calculations, only rarely by measurements. This approach is the opposite of artificial lighting design, which is done within the in-design phase by calculations and is verified by measurements in post-realization phase. The verification of artificial lighting design is required by the building and public health authority otherwise buildings cannot be approved to use. In the field of daylighting, measurements could be performed as well, nevertheless those are often problematic because regulations usually require fulfilments of the daylight factor which can be determined only under CIE overcast sky. Howbeit, both artificial lighting and daylighting measurements are influenced by many errors, e.g. errors of light measurement instruments, measurement conditions, measurement methods and human factor. The paper is focused on this aspect of lighting design, more specifically on the daylighting measurement errors.

The study capability of pupils depends on many factors. One of the factors is the level and the quality of daylighting in classrooms. The daylighting quality is particularly important for very young pupils in primary schools and nurseries. This article deals with natural light in classrooms with different school equipment and furniture and various parameters of window constructions.