The aim of the research is to analyse overheating risks in buildings in a summer season under Latvian climate conditions both experimentally and numerically. Three different building solutions are observed: two building structures which mainly consist of the mineral wool and wooden materials and one structure from aerated clay bricks and mineral wool. The experiments have been implemented in test stands in Riga. The possibilities of PCM using are tested too. The numerical simulations have been performed using software WUFI Plus. The results show that the light constructions have high overheating risks.