A novel greywater heat recovery system was modeled. The system that was modeled recovers wasted heat from greywater and applies it to preheating water for a hot water loop, serving a radiant floor heating system and domestic hot water consuming fixtures. The research focused on creating a valid energy model using eQUEST in order to determine the performance of the system. The sample building was a 39 unit apartment building located in South Lake Tahoe, California (ASHRAE Climate Zone 5). The system was observed from the point of view of Energy Savings, as well as the associated financial savings. The system was found to save 63 MWh of energy annually compared to a baseline model. It also was found to cause a 40% decrease in the overall combined energy consumption for Space Heating and Domestic Hot Water heating. This translates to an annual savings of $10,623.
