Domestic Hot Water Energy Modeling
Builders often ask us about the impact of different domestic hot water systems on whole building energy use. This motivated a study on how much energy various DHW systems use (storage tank versus instantaneous heaters), the impact of where you store it (in a conditioned space versus an unconditioned space) and the potential energy savings of water heater blanket.
One question is whether a DHW system stored in heated space should be insulated with a blanket. If it’s not insulated, the jacket losses from the tank help heat the home and offset space-heating costs. So the question becomes, is your space heater more efficient than your DHW heater? This study investigated when it was economical to insulate your water heater, based on the efficiency of your space heating appliance and your DHW appliance. The papers also discuss the pros and cons of tankless systems and tips for improving your DHW system efficiency.
Insulating your water heater Tankless water heaters DHW Calculator (Excel spreadsheet)