The nowadays climate warming trend is of significance because it is related with the human activities starting from the mid-18th century. This climate warming coincides with the increasing of the greenhouse gases concentration in the atmosphere, especially carbon dioxide. Some solutions, like urban agriculture, are aimied to oppose this phenomenon. We are studying a solution to increase the carbon sequestration in urban environments – the rooftop greenhouse buildings - and this work introduces an useful tool for assessing the efficiency of projects of this kind, respectively a fuzzy expert application, made in MATLAB, for real-time estimating the carbon sequestration capacity.