Analysis of Polish norms on thermal resistance and thermal comfort for underfloor heating

Abstract

In the paper, there is an analysis of the requirements for the thermal resistance of floors with underfloor heating. It corresponds to the human physiology as much as possible, creates comfortable conditions at a lower temperature of the internal air, reduces the rise of dust by reducing convective flows, allows the use of low-grade heat carriers, especially from secondary and renewable energy resources, does not take up space in the room, minimally affects the interior. However, the temperature of the heating elements is significantly higher than the room temperature. At the same time, the requirements for thermal insulation under the heating elements should be higher than for structures without heating. As the analysis of the regulations in force in Poland has shown, this is not always observed. In many cases, the heat transfer resistance is lower by 42-181 %. The percentage difference in requirements for flooers over aisles in rooms with an air temperature of 16 °C and above is 160%. It will reach 215 %, according to the requirements that will be applied from 2021. In the case of floors over unheated rooms, the percentage difference between the requirements reaches 181 %. By the new norms in 2021, this difference will reach 215 %. Also, the normative limitation on the temperature of the floor surface does not always allow providing the normative level of comfort. In rooms of categories A and B, the surface temperature of the floor must be 20-28 °C. In the case of category C it should not exceed 30 °C. The most favorable conditions are achieved when the floor surface temperature is close to 23.5 °C. PN-EN 1264-4 standard allows the temperature of the floor surface in some rooms up to 33...35 °C. Thus, to ensure energy efficiency and comfort, it is necessary to harmonize the regulations with each other.