1. A computer-implemented method of optimizing demand-response (DR) of a heating, ventilation, and air-conditioning (HVAC) system of a building, the method executed by the computer comprising the steps of: determining a value of an objective function F ij of a HVAC system for each of a plurality of DR strategies j for each of a plurality of weather patterns i that is a weighted sum of an energy cost of the HVAC system and a thermal comfort loss of the HVAC system; assigning a likelihood score L i,j to each of a selected subset of near-optimal DR strategies j for each weather pattern i; and selecting those near-optimal DR strategies with large overall likelihood scores L j to create an optimal strategy pool of DR strategies, wherein said optimal strategy pool can be searched in real-time for an optimal DR strategy for a given weather pattern.