The ETE energy controller reduces energy costs up to 35%. Central domestic hot water (CDHW) systems are common in multifamily (MF) buildings. They allow residents hot water with minimal delays. While this operation delivers hot water on demand, a significant amount of energy is lost during low demand. ETE has identified several ways to increase energy efficiency of a CDHW system while allowing an immediate return on investment. Whether you own or manage an apartment or condominium complex, we can deliver a noticeable savings in your costs for heating hot water.