The basics of environmental management systems according to the International Standard ISO 14001:2015 are described in this thesis. Environmental aspects are essential parts of every environmental managment system and are defined as an element of an organization's activities or products or services that interacts or can interact with the environment. Possible methods for identifying environmental aspects and their associated environmental impacts, assessing environmental impacts and methods for defining significance are described according to available literature. For the purpose of this thesis two organizations were analysed, The Faculty of Geotechnical Engineering in Varaždin and THE ORGANIZATION. The subject of the analysis were their methods for identifying environmental aspects, assesing environmental impacts and defining significance of their aspects. The two methods for defining significance used in the example of The Faculty of Geotechnical Engineering were compared as well as methods for defining significance of the two organizations. Conclusions and rules regarding aspects and environmental impacts of different organizations and conclusions about the existence of general rules in the processes of identification and defining significance of environmental impacts have been given in the conclusion.