Demand Response (DR) has gained so much importance due to its effect on load profile characteristics. The focus of this paper is on impacts of flexible load participation in day-ahead energy market, in which bulk power consumers introduce their load reduction as generation. Based on costumer's characteristics, a model is developed for the demand side participation in aforementioned program. Effects of demand side cooperation and various incentive policies on load profile have been surveyed by the help of the proposed model. Moreover, results were compared for several cases in order to prioritize various strategies.