The house was about 3000 ft2 total electric and equipped with a Honeywell system that consisted of a programmable HVAC thermostat and hot water heater controller. Out of sight in a closet was a black box having the brains of the system and a modem connecting the house to the power company. HVAC was by a high end heat pump. Funding for the system was by the power company as a research project.
Basically, the were 4 energy rates that were something like 0.7, 3.5, 7 and 11 cents/kWh coinciding with low, medium, high and emergency rates. Normally, the 3 normal rates engaged on a fixed schedule and emergency reserved for extraordinary situations.
It took only a couple of weeks to get the system set points programmed to our lifestyle and comfort. The temperature HVAC set points were adjusted by time of day and the rate tier in effect. The hot water heater was tired on and off based on when we are at home or not.
For example, on weekdays the hot water heater was only powered up about 6 hours a day for about 2 hours in the morning and 4 hours at night. The dishwasher had a start time delay so ran it after 11pm when the low tier rate was in effect plus the electric to the hot water heater was turned off. Most clothes washing and drying was on the weekend when the low tier rate was engaged from 11pm Friday to 6am Monday.
There were more bell and whistles to the system but the bottom line is I liked it a lot. Monthly electric bill was about $75. When we moved back to Houston, I wanted to get it for the house there. I finally found a person at the power company that didn't think I was nuts and was familiar with the Honeywell system. As a company, they were reserving the variable rate options to large commercial and industrial customers.
California's mandating of a variable electric rate is a scary proposition. It would be devastating economically to be in an emergency rate tier for any length of time.
My team did a Real Time Pricing research project in the late 80s at the World Financial Center in NYC (across the street from the World Trade Center). Honeywell was our contractor for the system and the research. We communicated rates from ConEd to the system a day ahead (which was a real challenge before the ubiquitous Internet, optical, and wireless communications systems we have today). The building had a HUGE “cool storage” system underground where we could “charge” it with cold during the night and then use the chilled water in the daytime to reduce rates during the hot afternoons. The system also measured indoor air quality so we could reduce air circulation and fresh air makeup, but not go so far as to adversely effect indoor air quality. The savings in the building were huge. We did a similar project at the Marriott Marquis hotel in NYC (without the cold storage) with similar results. My boss was the guy who really innovated all the early “demand side management” concepts and R&D at the time.
I have variable right here in central Indiana!