Growth analyses of the world population show, that in the next 30 years, the population of the planet will increase by 20 %, which means that demand for residential units will also increase. The thesis presents a new concept of constructing environmentally friendly wooden multiapartment modular building as an alternative to energy consumptive and environmentally unfriendly classical building. The paper deals with the construction of energy efficient wooden multi-apartment modular building. We constructed construction elements and with programs URSA 4 and THERM 7.3 verified their compliance with the current Regulations on energy efficiency in buildings PURES 2010 and Technical guideline TSG-1-004. With THERM we will analyze the most critical intersections that occur in the building envelope of designed building. The results will be used to calculate the energy balance of the building. The energy balance will be calculated with program URSA 4. The results will be verified according to criteria laid down in the Regulations on energy efficiency in buildings. With results we want to show, that with the proper approach to constructing the building envelope and the supporting system, an effective modular system can be created.