This thesis focuses on a mountain cottage design which satisfies insulation properties of a passive house standard, using cross-laminated timber as a structural system. The cottage is situated in a mountainous area near Popradské pleso. The thesis also contains a characteristic of the construction system made of CLT panels, a description of the requirement of passive buildings for the construction and needs of energy for heating, as well as the methodology of the assessment of the object, according to which we proceeded. The next section contains a technical description of the projected wooden building. This is followed by the energy balance and the annual energy consumption of the building using the PHPP tool, taking into account the thermal linear bridges of the object ascertained by the Therm software. The thesis also includes the water vapour condensation assessment in the chalet external envelope. The thesis ends with an evaluation of the building from the point of view of energy consumption for heating and a design of a heating system. The project documentation was created in AutoDesk - Autocad software.