Hacker News Reader

Those accurate energy-saving models IMO fall apart because they keep buildings just a bit uncomfortably warm or cool, leading everyone to bring in plug-in space heaters, dehumidifiers, and fans. One other trick in the summertime when the central operations folks have decided that the building is cool enough but everyone is sweating, is to bring in a space heater and put it under the thermostat.

View on HN

Ah, but it's not always done for comfort optimization.

Older electrical meters weren't all that accurate, especially for larger systems - that's true even today. They're analog as an only option of measurement due to incredible amounts of power going through them (too noisy for hall effect sensors). Large buildings are reactive loads to the grid, almost like an inductor. Anyhow, older meters picked up velocity for usage calculations.

Some A/C controllers carefully modeled how fast the power meters accelerated as an instrument, then used that information against them, throttling and ramping power use to slow the measurements down, basically causing under-metering.

Saved USPS millions a year in power bills.

Reply on news.ycombinator.com