The thermal performance of a building is directly related to the materials that are composed. The roof is the part of the envelope that is most exposed to direct solar radiation and thus has a strong influence on the transfer of heat to internal environments. Vegetated cover is suggested as a technology for aid to reduce energy consumption in buildings. This research refers to a hypothetical case study on the applicability of a vegetated cover system in a public educational building (computer laboratories) in Florianopolis city over a period of one school year. In order to achieve the objectives of this study, numerical simulation was carried out in 3 proposed situations through the EnergyPlus programme, material budget through SINAPI, determination of a minimum rate of attractiveness and application of financial economic viability analysis techniques (VPL, Payback and TIR). The maximum savings with electricity consumption for refrigeration was 8.7 %. As a result, the budget for vegetated cover has been found to cost approximately three times as much as conventional asbestos-cement cover. For all situations negative Net Present Value (LPV) was obtained and the Internal Return Rate (IRR) did not exceed the determined Minimum Atraction Rate (MAT). In the best thermal performance situation, in order for the initial investment to be fully recovered, i.e. to have its VPL zero by the cut-off date, 27 % of the investment would still have to be recovered.