The Philippines is in a tropical location where rainwater is abundant for the frequent rain in a year. Rainwater becomes waste flowing down the drains causing flood, especially in urban areas. This problem initiates local governments in some cities in the Philippines to adapt and implement Green programs that require the installation and utilization of rainwater catchment system. Though this program addresses the control of flood caused by the rain, the generation of energy by utilizing rainwater as an energy source is not yet considered. With this, the study computes the equivalent energy generation by utilizing rainwater. The rainwater energy equivalent includes the following: the increasing number of high-rise building construction as catchment facility; the rainfall precipitation of 58 stations in the Philippines; the floor area and the types of the building; and the volume of water consumption per person per day. The energy equivalent was computed using the 40% of the time the rainfall precipitation equaled or exceeded the other with the average floor area specified from the approved building permit as of 2017. The study established a mathematical equation as an equivalent energy of rainwater utilization. The equation of energy equivalent was derived using the initial building height of 5 meters and an additional succeeding height of 3 meters per floor level.