Clients are demanding demonstrable performance for their buildings with a focus on long-term energy performance, particularly as the effects of climate change become more pronounced. In order to have the greatest impact on energy performance we have developed in-house capacity with a number of performative design tools including LightStanza Daylight Simulation and the Passive House Planning Package. We utilize these tools to develop accurate early phase feedback loops for the design process to maximize building performance, and also to ensure compliance with Green Rating System credits.