The paper highlights the problems associated with daylight use in industrial facilities. In a case study of a multi-story textile factory, we report how to evaluate daylighting (as part of integral light) in production halls marked F and G. The post follows the article in the Buildings journal, where Hall E was evaluated (unilateral daylight). These two additional halls have large areas of 54 x 54 meters and are more than 5 meters high. The daylight is only on the side through the attached windows in envelope structures in the vertical position. In this paper we want to present two case studies of these two production halls in a textile factory in eastern part of Slovakia. These are halls that are illuminated by daylight from two sides through exterior peripheral walls that are against or next to each other. The results of case studies can be applied in similar production halls illuminated by a “double-sided” double (bilateral) daylight system. This means that they are illuminated by natural illumination through windows on two sides in a vertical position. Such a situation is typical for multi-storey buildings in industry. The proposed approximate calculation method for daylight factor can be used to predict daylight in similar spaces in other similar buildings.