Different methods are used to assess the sustainability of a building. In Slovenia, there is no national method for certification of sustainability of buildings, but it is possible to evaluate buildings in Slovenia using other methods, such as BREEAM, LEED, HQE, DGNB, WELL, etc. They differ according to scoring, categories and criteria. The purpose of the thesis is to explore the notion of sustainability, to be familiar with the legislation and methods of assessing the sustainability of buildings. In the second part of the diploma thesis, we analyzed the possibility of assessing the sustainability of the building (Residence Home on Regent Street in Ljubljana) on the basis of the project documentation (PGD). We are interested in how much information about the sustainability of the building can be obtained from the documentation (PGD). For this part, we used a method, adapted on the basis of the Simple tool for building sustainability evaluation from the doctoral dissertation of Jernej Markelj. The method is total of 34 criteria in three aspects. These are environmental, economic and sociological aspect. From the analysis, we see that 20 criteria (61,8 %) are mentioned in the PGD, 12 criteria (32,3 %) are not mentioned, and 2 criteria (5,9 %) are partly mentioned. Based on the relevant provisions, we can collectively evaluate 16 criteria (47,1 %) and we can not evaluate 18 criteria (52,9 %). We have found, that based on the project documentation (PGD), we can not completely check all 34 criteria of sustainability of the building. Improvemens will be needed to include all information in the design phase, in order to verify that all sustainability criteria are met.