The Hall County school board is set to vote on implementing phase one of a districtwide energy-saving plan at its meeting tonight.

Phase one, which Hall County Schools' SPLOST Coordinator Damon Gibbs said will cost about $1.7 million in special purpose local option sales tax money, will upgrade the heating, ventilation and air conditioning technology in Hall County middle and high schools. Phase two, which the board will look at in the spring, will upgrade HVAC systems in the county's elementary schools.

All Hall County schools received some form of HVAC upgrades over the past 10 years, but the new plan will put all schools at the same level of energy efficiency.

"We've kind of piecemealed (the upgrades) at all of the schools. We didn't have the money to get this done at all of the schools at that time," Gibbs said. "Phase one will be middle and high schools because they are the highest consumers. They're the biggest buildings with the longest hours and have more after-school activities."

There are three components to the upgrades — direct digital control, load shedding and occupancy sensors.

Gibbs said the way power bills are structured, the school board sets limits on how much energy it wants buildings to consume, and the more power used, the more the board must pay. That's where load shedding comes in.

"Basically, we can tell the system we don't want to up our rate structure. The system will go in and increase the temperature of areas that are unoccupied," he said.

Occupancy sensors will help aid that process. If the sensor doesn't detect movement in a classroom or school area, it will turn off the lights and increase the temperature.

"Take an elementary school for example. You take the entire grade level on a field trip. Those teachers turn the lights off when they leave but the AC would run all day," Gibbs said. "This will stop cooling at the occupied temperature. It's almost (as if) the system is smarter than we are."

Gibbs estimates phase one will save the system $475,000 a year in energy costs. He said he expects to see returns in three to five years.