In recent urban buildings, there is an interest in using wind turbines inside the buildings. Thus, the rotors of wind turbines are shrouded by the walls of the buildings. A design for using wind turbines in urban areas is to use shrouded turbines on the roof of a building. Since vertical axis wind turbines (VAWTs) with low environmental impacts are recommended for energy supply in urban areas, here, the interaction of two shrouded VAWTs has been studied numerically. Based on the effects of different shroud parts, the diffuser‐shrouded turbines are selected. The arrangement of diffuser‐shrouded VAWTs has been optimized using the response surface method optimization with the Kriging model. The optimization samples are chosen by the design of experiment method to reduce the number of simulations and increase optimization accuracy. The total power coefficient of the optimized cluster is 46.2% higher than the sum of the same individual diffuser‐shrouded turbines and 149.6% higher than the sum of individual bare VAWTs. The economic assessment shows that the levelized cost of energy of the optimized cluster of two diffuser‐shrouded VAWTs is reduced by about 40% compared to two bare VAWTs.