"Consumer Strategies for
Controlling Electric Water Heaters under Dynamic Pricing"
Chong Hock K. Goh and Jay Apt
Electricity used to heat water represents 9% of residential demand in
the USA and can be 40% in other countries. Hourly residential use of hot
water is often anti-coincident with the peak generation of electricity,
presenting an opportunity for reducing consumer costs under dynamic
pricing during the afternoon generation peak. We have examined the
effects of three strategies on customer costs under dynamic pricing:
timed power interruption (long used by certain utilities), a
price-sensitive thermostat, and a double period setback timer. Systems
which lower the water temperature set points are as economical as power
interruption systems, and result in higher minimum water temperature.
Our model predicts that a setback thermostat will keep the tank water
warmer than a load interruption timer with very similar electricity use.
The setback thermostat and the more complex price-sensitive thermostat
achieve similar water temperatures and consumer savings.
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