Increasing the efficiency of water heating equipment is one means to achieve energy savings in the hot water system; however, the piping distribution system itself is now being scrutinized to determine opportunities for further hot water system savings. Often accepted approaches to energy savings in the hot water piping system are to reduce the length of piping to the outlets and to insulate the hot water pipes. Less regarded as an energy savings feature is the reduction in size of the hot water lines to outlets, which can reduce pipe losses, as other plumbing system performance issues such a pressure drop and fluid velocity must be considered. All of these approaches will result in lower piping system losses. The purpose of this study is to outline the mechanisms of energy savings in the piping distribution system and to estimate the range of energy savings resulting from pipe insulation based on simulated hot water use profiles.
This study was commissioned by the National Association of Home Builders (NAHB) with the purpose of understanding the energy savings available by insulating hot water piping in homes relative to the cost of the insulation, both in materials and installation. The study includes references to the existing body of research as well as results of new analyses of hot water distribution systems with various options for insulating hot water piping.