Critical heat flux densities of various flooring materials for outdoor applications

The thermal properties of building materials play an important role for human well-being. When there is skin contact between people and building components like for example, flooring materials, the ability of these components to release or draw heat needs to be considered. In this study, a method was developed to determine the heat flux density between a flooring material and the human skin. Therefore, the temperature increase in a silicone-embedded temperature sensor mimicking the skin was recorded and used to determine the heat flux density expected from the material in terms of the heat transfer coefficient. In total, heat transfer coefficients were determined for 33 different outdoor flooring materials: 16 wood species, five metals, three polymer-based compound materials and nine minerals. To adjust the results from the heat flux density measurements applied at the differently heated flooring samples, 40 test persons were chosen to estimate their subjective thermal sensation. Materials showing heat transfer coefficients above 40 W/(m 2 K) were associated with a subjective sensation described as “inconvenient” to “painful” at high surface temperatures. All wood species revealed heat transfer coefficients below this critical value. Contact to polymer-based compounds, minerals and metals led to higher heat flux densities, which were clearly correlated with the material density.