## 4 Results
### Radiant Systems Efficiency
This comparison has been carried out since the embedded emission according to EN 15316 [37] has to be calculated in steady state conditions as the ratio between the useful thermal input in the indoor environment and the overall power delivered by the water in the pipes. Even though they are calculated in steady state conditions they are then used in the energy performance of a building on a monthly or seasonal base. The analysis of EN 15316 will be considered again later, at the end of this paragraph. As can be seen, the red line of the climatic control is on average slightly above the blue line of the constant supply temperature control modality. In well-insulated light buildings the efficiency is almost the same (98-99%) regardless the type of radiant system used. These buildings present 2% higher efficiency compared to masonry structures; with these last structures there is no difference among radiant systems in climatic control strategy, while with constant temperature the wet floor performs slightly better. The results of well-insulated buildings of the period December-February (Figure 6) are very similar to the ones related to the whole season (Figure 7), since the energy evaluated in this period takes into account 90% of the heating demand of the whole season. In non-insulated buildings and in insulated buildings usually the dry floor radiant system performs slightly worse than both the wet floor and the ceiling system (about 2%). In these cases when considering the whole season instead of the period December-February there is a 2% difference in the embedded and control efficiency. The interesting aspect is that the embedded and control efficiency calculated via dynamic simulations (Equation (5)) is higher than the embedded efficiency calculated via steady state conditions (Equation (6)). In light well-insulated structures the embedded and control efficiency of dynamic simulations is 1.5% better than the embedded efficiency estimated via FDM (1% if considering the period December-February, 2% if the whole season). In masonry well-insulated buildings the embedded and control efficiency of dynamic simulations is 3.5% better than the embedded efficiency estimated via FDM with constant supply temperature (3% if considering the period December-February, 4% if the whole season), while dynamic simulations provide 4.5% better embedded and control efficiency than the embedded efficiency estimated via FDM in the case of climatic control (4% if considering the period December-February, 5% if the whole season). In insulated buildings the difference is almost 4% regardless to the water supply temperature, while for non-insulated buildings the difference is 6%. It is useful to highlight that the efficiency calculated via FDM is evaluated with constant indoor temperature and in steady-state conditions, as usually done by producers of radiant systems and practitioners and, therefore, depends only on the difference between water temperature and room temperature and on the thermal conductivity of the materials of the various layers, but not on their thermal capacity. In dynamic conditions the situation is completely different, both for the water inside the pipes and for the boundary conditions. For most of the time the heat load required by the heated room is lower than the design heat load, and hence warm water is not continuously flowing in the pipes of the radiant system. The changing indoor conditions and the consequent on-off operation of the radiant system lead to a complex mechanism of absorption and release of heat in the different layers of the floor and the percentage losses results lower than in steady-state conditions. This means that part of the heat delivered by the pipes is absorbed by the layer containing them and, when water stops flowing, part of this becomes useful gain instead of backwards loss.