If you build it, they will find a way to overcharge you. That seems to be the lesson the Durst Organization is learning as Con Ed keeps finding ways to bill the oh-so-green Bank of America tower off Bryant Park. For the second time in a year the Dursts have accused Con Ed of trying to overcharge them. Giant real estate companies, they're just like us!

The issue this time is the building's "cogeneration system" which produces its own electricity for the building, specifically using natural gas Con Ed sells it to run the system:

Most of the natural gas piped into the building from beneath 42nd Street near Bryant Park fires the power plant. Rather than waste the exhaust from that combustion, the system feeds it into a boiler that produces steam to heat and cool the tower.

But that equipment, known as a heat recovery steam generator, is not always sufficient. When it is not, a gas-fired backup system produces additional steam to help with the heating or cooling.

For the first year or so of the building's life Con Ed was selling the gas for that backup system at a discount, but now that other buildings are popping up and asking for the same thing it's no more mister nice utility. The power company argues the lower rate is only for gas used to generate electricity, not for producing steam.

This isn't the first spate between the two. Earlier this year the building got in a tiff with Con Ed over how it estimated (or overestimated) the building's peak demand (the building won, for the time being). Now the Dursts are arguing that by making their eco-friendly system more expensive to run Con Ed and its peer are making it harder to persuade other developers to build similar buildings. So how much money are we talking about? Oh, about $86,000.