Increased urbanisation has led to a worsening in the quality of life for people in large cities due to the increase in indoor temperatures. Retrofitted green roofs may attenuate housing temperatures, due to the isolation and passive cooling properties of these vegetated systems. For this purpose, this research reports on an experiment using a green roof modular system to compare indoor and outdoor temperatures before, and after, a green roof set up in an existing depot in Rio de Janeiro, Brazil characterized by high temperatures for most parts of the year. The modular system comprised previously used pallets covered with geotextile and planted with succulent species with low watering needs and reduced maintenance processes. Compared to the outdoor environment, mostly warmer indoor conditions were converted to cooler temperatures and due to its thermal properties, which provide insulation, evapotranspiration, and shading the green roof system presented a potential to attenuate the heat exchange and improve indoor conditions. A homemade lightweight modular system can widespread green roofs on a city scale.

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