Software HeatMod (actual version 5.21) is made in Delphi environment (as 32 bit Windows application). Its purpose is to model heat consumption (in correspondence with requirements of DIN 4108 ) of finished and planned buildings and perform qualitative analysis of different reconstruction variants. In new actual version it is possible to made calculus according to Latvian Building Code LBN 002-01. Also it is possible to calculate heat transfer coefficient for various heterogeneous walls with many different layers.