In recent years underfloor heating is getting more and more popular as a whole heating system for all premises not only the bathrooms. Share of underfloor heating compared to such traditional heating systems like radiators or air heating systems is increasing, thanks to better building envelope insulation level, need for higher comfort level and potential to use such modern energy sources like heat pumps that uses ground water, soil or air energy. Relatively low temperature in heating mode and high temperature in cooling mode and minimum temperature difference between supply and return allows to increase coeficient of perfomance (COP) of heat pump or efficiency of a gas condensation boiler. Often the architects and the customer are interested to install underfloor heating, but one of the main concerns is about thermal comfort next to glazed surfaces in residential buildings as well in office buildings. The aim of the paper is to analyse thermal comfort of people near the outside glazed surfaces taking into account comparatively low outside calculation temperatures. Calculations where made based on the applicable European norms (EN). Seven different U-values for outside glazed surfaces where analysed at room temperature 200C and outside temperature -200C, analysis include radiant asymmetry and downdraught calculations. Results shows that using outside surfaces with U-value below 1.5 W/m2deg is acceptable to ensure thermal comfort according to European standarts.