DesignBuilder is a state-of-the-art software tool for checking building energy, CO2, lighting and comfort performance. Developed to simplify the process of building simulation, DesignBuilder allows you to rapidly compare the function and performance of building designs and deliver results on time and on budget. DesignBuilder combines rapid building modelling and ease of use with state of the art dynamic energy simulation. DesignBuilder is easy to use. Its innovative productivity features allow even complex buildings to be modelled rapidly by non-expert users. DesignBuilder is the first comprehensive user interface to the EnergyPlus dynamic thermal simulation engine.