## 4 Conclusions  
The thermal behaviour of 60 radiant wood floors and one granite floor as a reference was simulated in 216 dwellings in 28 cities around the world, selected according to the Koppen-Geiger climate classification, with the aim of answering the questions posed in the introduction of this article. The main conclusions and answers to each of these questions are presented below. A more in-depth analysis supporting the conclusions presented here can be found in Section 3. * In general, the results showed that in all the climates studied it was possible to find wooden floors with a thermal performance practically identically to granite in terms of energy demand and thermal comfort. One finding of note was that the best-performing woods delivered slightly more thermal comfort hours than the granite floor, with the exception of climates with extreme winters, where it could still be possible to find wooden floors delivering comfort levels close to those of granite. In all the climates,  
Figure 12: Mean percentage of dwellings meeting the minimum comfort requirement of 14 h a day with top \(\geq\) 20 \({}^{\circ}\)C versus thermal resistance of covering for five selected cities. it was possible to find some wooden floors that exhibited start-up lag times close to those of granite. * The first question posed was: are the lowest thermal conductivity woods appropriate/suitable for use in radiant floors? According to the findings of Section 3.3, a priori, in terms of energy demand and thermal comfort, the lowest thermal conductivity woods should not be rejected for use in radiant heat floors solely on the basis of their thermal conductivity. The findings showed that wood floorings with low thermal conductivity were able to provide thermal comfort with low energy demand in every part of the world. Specifically, woods with conductivities below 0.18 W/(m\(\cdot\)K) presented the lowest demand, complying with comfort in just over 50% of the cases studied, and more specifically, the wood with the lowest conductivity (0.1 W/(m\(\cdot\)K)) did so in no less than 10% of the cases. In the same range, namely below 0.18 W/(m\(\cdot\)K), the wooden floors provided the highest number of comfort hours in 30% of the cases. Furthermore, based on the results in Section 3.3, there are cases in which the lowest values of thermal conductivity do not lead to excessive increases in the start-up times compared with granite. * The second and third questions were: should there be a maximum limit of thermal resistance of the flooring in radiant heating systems? And, is the standard thermal resistance limit of 0.15 m\({}^{2}\) K/W objectively justified? In view of the results in Section 3.4, in all climates it was possible to find dwellings in which any value of thermal resistance of the wooden floor provides similar comfort to a granite floor with similar energy demands. This suggests that there are no reasons to set a limit value for thermal resistance that can be universally valid to ensure low energy demand while satisfying comfort conditions. In any case, in the event of having to choose a thermal resistance limit value, a plausible criterion would be for it to be established according to the mean behaviour of the dwellings in a specific climate. In this case, the only city where setting this limit would be necessary is Yakutsk, the coldest city included in this study, and this value would be approximately 0.10 m\({}^{2}\) K/W. * Finally, the fourth question was: do the answers of the preceding questions depend on the climate and the building construction? The answer is yes. Building characteristics and climate can be important factors when selecting the thermal properties of the floor covering to deliver thermal comfort with low energy demand and reasonable start-up lag times. According to the findings of this research, the choice of a given wooden flooring had little impact in cities with mild winters such as Madrid or La Paz for almost all the dwellings simulated.