Window is an opening in a wall which allows the passage of light and if closed it protects us from environment effects such as temperature, wind and UV light. There are several types of materials used for window frames, namely: polymers (most commonly PVC), aluminium and wood. There are also combinations of different materials applied, wood-aluminium being the most common. Joints, that are used for construction of the wooden frame are usually tenon or dowel joints. In respective thesis comparison of modern wooden windows with tenon and dowel joints was performed. Wood moisture content in different parts of window elements was monitored twice per day. In order to expand the research temperature of the inner surfaces in window frames was logged as well. Additionally, colour on different parts of outside surfaces on windows was determined as well. The advantages of the dowel join is that surface coating covers all of the window surfaces, before it is assembled, which means that you also protect the axial planes of the elements. Meanwhile the windows made with tenon joints, are surface coated after being assembled, hence the axial planes are not protected. Additionally, tenon joint exhibits better statics of the window and the strength of the joint is higher. However, studies and experiences of manufacturers and users confirm that the dowel joints static is sufficient. Due to the short duration of the experiment, the differences in wooden moisture content between various windows is not significant. The differences in temperature and colour changes are more prominent because of the positioning of aluminium profile and the different brightness of the surface coatings applied on the windows.