## 5 Conclusions and Discussion  
The work carried out is based on simulation of a room which represents an intermediate multi-story flat of about 100 m\({}^{2}\) where three types of radiant systems have been modelled: two radiant floors (one with usual pipes embedded in wet screed and one with low thickness dry screed) and a radiant ceiling. The work looks at the performance of these systems in heating conditions with three insulation levels of buildings: no insulation, insulated building and well-insulated building. Three types of insulated buildings (with internal, intermediate, and external insulation) and four types of well-insulated buildings (masonry with external and internal insulation, timber structure, and light structure) have been analysed. Dynamic simulations of the radiant systems with fixed temperature and with variable temperature according to outdoor temperature have been compared with an ideal convective dynamic simulation. Results have been analysed in terms of control and embedded efficiency of the radiant system, energy performance of the radiant system with a water to water heat pump at fixed source temperature, as well as possible overtemperature. About the embedded and control efficiency, the climatic control strategy performs slightly better than the constant supply temperature control modality. In well-insulated light buildings the efficiency of the two control strategies is almost the same (98-99%) regardless of the type of radiant system used. These buildings present a 2% higher efficiency compared to masonry structures, with these last structures the different types of radiant systems show the same efficiency value in case of climatic control strategy, while with constant temperature the wet floor performs slightly better. In non-insulated buildings and in insulated buildings usually the dry floor radiant system performs about 2% less than both the wet floor and the ceiling system (which present circa 96% of efficiency). The embedded and control efficiency calculated via dynamic simulations has been compared to the embedded efficiency calculated via steady state conditions. In light well-insulated structures the embedded and control efficiency of dynamic simulations is 1.5% better than the one estimated via FDM. In masonry well-insulated buildings the embedded and control efficiency of dynamic simulations is 3.5% better than the one estimated via FDM with constant supply temperature, while climatic control simulations provide 4.5% better embedded and control efficiency than the one estimated via FDM. In insulated buildings the difference is almost 4% regardless to the water supply temperature, while for non-insulated buildings the difference is 6%. The old version of the standard EN15316-2-2007 [37] provides for the embedded and control efficiency 90% for the wet floor and ceiling systems and 91.3% for the dry floor system. The dynamic simulations provide for the wet floor and the ceiling as average 96% in non-insulated buildings, in insulated buildings and in masonry well-insulated buildings, 98% in well-insulated buildings with light structures. The dry floor presents an embedded and control efficiency of about 93% in non-insulated buildings and in insulated buildings, 95% in masonry well-insulated buildings, and 98% in well-insulated buildings with light structures. Referring to the new version of the standard 15316-2-2017 [38], the current values of the temperature difference \(\Delta T_{i,emb}+\Delta T_{i,ctr}\) are higher than the ones calculated in the present work. Based in the dynamic simulations, the suggested values for the joint embedded and control temperature differences are the ones reported in Table 8, which should substitute the existing default values. Moreover, the efficiency calculated in transient conditions is higher than the efficiency calculated under steady state conditions. This result is because, over the season, the radiant systems work for some hours and then they switch off.