People have always been surrounded by nature so, the building of that antinatural construction causing such a high global impact on environment, never made any sense. Global warming will become a big issue in a few years’ time, basically in our cities. Human society can protect, manage and restore ecosystems actively to improve the climate change challenge. The concept of Nature-based-solutions (SbN) appeared as a green solution in the pollution in cities. This research project aims to study the SbN by describing its types: vertical gardens and more important, the one given to green roofs. The investigation part consisted of studying and experimenting the benefits of green roofs in buildings and cities comparing them to traditional roofs. The investigation was divided into four parts by analysing the three examples of roofs (type of meadow, Sedum sp. and small stones as the traditional one) at the house garden. First, watering, taking care of the plants and preparing the experiments. Then programming an Arduino, data logger and humidity and temperature sensors. Third, obtaining data, making graphics and comparing what happened to each one, and considering the benefits. And the final experimental part consisted of measuring the capacity of water retention of the example of the roofs, and particularly in the city of Lleida. The conclusions obtained from the results, prove that green roofs would represent a significant improvement in the city, instead of the traditional ones, using Sedum sp. or meadow roof (depending on the country weather conditions). Green roofs act as thermal insulation in buildings, with future significant energy savings during the year, and with probable economic benefits in cities and its own infrastructures.