The zero energy level for buildings can only be achieved by only consuming very small amount of energy for heating, ventilation, electricity and hot water so this energy can be produced by renewable sources. Therefore these buildings will be similar to today’s buildings of passive house standard. The paper provides calculation method and conclusions about what should be the necessary thickness and heat transmission coefficients of insulation for opaque elements - exterior walls, ground slabs and roofs as well as the optimal sizes of the windows, their orientation and heat-technical properties to achieve passive house standards in Latvian climate. This has been done for one story single family house representing hard to achieve passive house case. For comparison the calculations have been done for five largest cities of Latvia which are located at places with maximally diverse climatic conditions for Latvian territory. Also the paper presents economical estimation and payback time calculation of passive house building constructions and engineer technical systems in Latvia.