Most articles about building performance refer to the management systems of commercial structures. Unfortunately, there is not enough discussion about the residential owners who think about or want system performance. In the case of one of our active residential projects in Kentfield, the owner heard about efficient home systems from a neighbor located in the same community. This Nordby Effect post discusses residential CoGen [also known as combined heat and power (CHP) systems] and the areas to consider during the project-planning phase.