Pulled interval data for a retail client in Phoenix on APS and noticed consistent 45 kW demand from midnight to 5 AM when the store is closed. Turns out three of six rooftop HVAC units are running 24/7 because the thermostats are set to "ON" instead of "AUTO." The units run the fan continuously even when there's no cooling call. The overnight demand is adding about $1,100/month in demand charges that shouldn't exist.
Rooftop units running during unoccupied hours
This is so common in retail. The store manager sets the thermostat and nobody ever checks it again. I found the same thing at a grocery store in Charlotte — two rooftop units running 24/7 with the setpoint at 68 degrees in an empty building overnight. Switching to programmed setback (78 degrees unoccupied) saved $840/month.
Overnight HVAC waste is the most common operational finding in retail and office audits. It's not a billing error per se but it's a legitimate utility cost reduction that clients value highly. I recommend every auditor check 24-hour interval data for unexplained overnight load. If the building is supposed to be unoccupied and the demand doesn't drop significantly at night, something is running that shouldn't be.
Thermostat reprogrammed. First full month shows overnight demand dropped from 45 kW to 12 kW. Savings confirmed at about $1,000/month. Simple fix.