Demand Response programs influence the end-user electricity usage by changing its cost along the time. In this scenario, to better manage the building's energy demand and consequently the electricity related costs, the user needs to estimate the energy demand and on-site production of the building in function of the electrical devices that are present on the building boundary. This paper presents an agent-based electrical simulator that has been built with the main objective of providing those tools to the consumer. The proposed simulator uses a hybrid «bottom-up» approach, with both statistical and physical models. The referred software is capable of estimating the energy demand and on-site generation with a 1-min time resolution for the period of 24h and calculates the energy price for each scenario. Therefore more control over the demand side is given to the end-user, allowing an easy response to changes in the electricity costs along the day. Such techniques could help the user to maximize the usage of renewable energy and to lower the electricity costs. On the other hand it is also beneficial for the energy provider since it is more likely to reduce the demand at peak hours.