Reducing energy consumption in buildings presents a challenge for the construction and architectural industries. Stakeholders in the building sector require innovative products and systems to reduce energy usage effectively. Building Energy Simulation (BES) tools are essential for understanding energy-related issues during the design phase. However, the existing BES tools are often complex and costly, making them inaccessible to many architects and engineers who lack the software expertise for integrating new systems into existing Building Energy Simulation frameworks. To address this gap, the authors of this article have developed a new tool that enables early-stage evaluation of building performance. Additionally, the tool includes Water Flow Glazing (WFG) as a construction element that is part of both the facade and the building's heating and cooling system. The authors validated the methodology by comparing the results from the new tool with those from the commercial BES tool Indoor Climate and Energy IDA-ICE 5.0 in accordance with ASHRAE standards. The same cases were tested by comparing the indoor temperature of a room with the power absorbed by the water, as measured by both tools. A WFG facade can effectively help maintain comfortable room temperatures throughout both winter and summer while producing renewable thermal energy via water heat absorption. The accuracy of this tool was validated using the normalized root mean square error between results from the new tool and those from IDA-ICE 5.0, which remained below the maximum allowable error established by ASHRAE. Validation of the tool using an experimental prototype showed that a coefficient of determination (R2) of 0.91 can be achieved through iterative refinement between the model and measured data.