Balconies are horizontal overhanging structures whose main function is a connection between interior and exterior space. Moreover, they increase an area of a room and they also can have a presentable, architectural and aesthetic purpose. There are a lot of requirements on the balconies, for example the requirements on static properties, thermal bridges, railings or fire safety. From the point of view of building physics, we can consider the balcony as the fixed shading construction which can reduce overheating in a shaded room during the summer but on the other hand the balcony can influence visual comfort in the room in a negative way. This article presents a comparison and an evaluation of the daylight factor in the rooms which are shaded by balconies. The influence of the balconies on the daylight factor is assessed in dependence on a length of the balcony (a balcony overhang) and dimensions of the room which the balcony shades.

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.

Daylight in buildings can be evaluated using dynamic and static daylight metrics. The daylight factor is a static daylight metric which evaluates daylight conditions under the overcast sky model according to the International Commission on Illumination. However, the dynamic daylight metrics (e.g. daylight autonomy, spatial daylight autonomy, useful daylight illuminance) can be more complex evaluation criteria because they are based on annual daylight illuminance data for a building site. While the daylight factor value depends only on a room geometry, optical properties of surfaces and positioning of daylight obstructions, the dynamic daylight metrics also include an effect of a building location, window orientation or building occupancy pattern. The article deals with a comparison of a daylight evaluation using dynamic and static daylight metrics in the case of buildings whose daylight is obstructed by external barriers.

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.

Daylighting is one of the important factors in the internal environment of buildings. The quality and quantity of daylighting depends on many factors including distances, heights, shapes and reflectance of surrounding external obstacles and ground reflectance. The quantity of daylighting is evaluated using the Daylight Factor. The case study carried out on a lighting simulation software and presented in this article demonstrates the influence of the light reflectance of external surfaces on the Daylight Factor. The aim of the article is the comparison and evaluation of the impact of the light reflectance of the external surfaces on the Daylight Factor.