As the interest in regulating energy usage and participating in the demand-response market is growing, new energy management algorithms emerge. Energy consumption of elevators represents about 5% of the overall consumption of a building. Thus, improving energy performance of elevators becomes a relevant challenge. In this paper, a method is described to assist potential customers in choosing the most relevant storage units and control method for their multisource elevator. In order to obtain a certification on electricity cost savings and maximum power peaks, a randomized algorithm is designed. The best storage units design is found for a given use case, and a guarantee (with a fixed probability) is given that the elevator's consumption from the grid will not exceed a given power peak. Moreover, a similar guarantee is given on the minimum savings that could be achieved, choosing a given controller.