This article provides information on the characteristic heat-related data of the enclosing constructions of the existing multi-apartment houses in Latvia as well as those of the sanitation systems in these houses.Monitoring of the heat energy consumption has been conducted in order to determine energy consumption over one-year period in a renovated nine-storey multi-apartment house of the 602 series design. The results obtained through monitoring have been compared with those of the heat energy consumption in an analogous reference house.