**5. Conclusions**

Consecutive experimental campaigns in a building with a conventional and with a green roof have allowed deducing the impact on the energy efficiency of the building air conditioning system due to green roof installation. In its application to a typical Mediterranean one-story building, insulation effects coming from the presence of the green roof introduced a small deterioration in that energy efficiency for the winter period, but showed clear improvements for the summer one. The global effect along the entire year is a net gain in the order of 19% for the energy consumption, but a 6% increase for the nominal power in the winter period. These results werededuced using a TRNSYS calculation, previously calibrated with the experimental data obtained for summer and winter periods. Therefore, in addition to the beneficial effects on the storm water control by reducing runoff and improving water quality, green roofs are also a significant element to improve energy efficiency in buildings and could help to mitigate urban heat island effect, while increasing urban biodiversity.

**Author Contributions:** J.C.-C. and E.P.-L. developed the methodology; J.C.-C., E.P.-L. and I.V.-S. prepared the conceptualization and data curation; E.H.-P., D.A.-S., J.C.-C. and E.P.-L. gathered and analyzed the data. J.C.-C. and E.P.-L. wrote the paper. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the European Union's Horizon 2020 research and innovation programme under the project Green Cities for Climate and Water Resilience, Sustainable Economic Growth, Healthy Citizens and Environments with reference 730283.

**Conflicts of Interest:** The authors declare no conflict of interest.
