Mold and air-quality concerns at King's Highway School will be history with installation of the most advanced HVAC system in the school district, officials say.

In addition to providing heating and cooling, the $2.8 million system will feature humidity and carbon dioxide sensors.

As with other older school buildings, there now is no mechanical way to bring fresh air into King's Highway School, so teachers have been directed to open classroom windows, even during winter.

Lack of fresh air, said Nancy Harris, superintendent of business for the Westport school district, can lead to sleepy students and also spur headaches. Middletown-based Consulting Engineering Services designed the system and Main Enterprises Inc. of Stratford, which recently gutted the east and west wings of the school, was awarded the HVAC project back in February, though full-fledged construction didn't begin until June 27.

"We are very pleased with the quality of the work, the subcontractors that they have hired and the progress that they're making," she said.

An investigation of air quality and mold at King's Highway School by administrators revealed mold in numerous areas of the building, as well as carbon dioxide levels -- due in part to poor ventilation -- exceeding 1,000 parts per million in the school's library, choral and guidance rooms and the auditorium.

Ventilation rates for schools and office spaces are defined by various codes and standards. Ideally, indoor CO2 concentrations are recommended to be maintained at, or below, 1,000 parts per million in schools and 800 ppm in offices.

As far as humidity, the report on King's Highway included the sentence, "As expected in buildings without mechanical systems for humidity control, the recorded levels were roughly comparable to atmospheric conditions."

That report prompted the decision to invest $2.8 million to correct the issues.

"Working with the town we jointly decided it would be best for the kids and the teachers if the school had a controlled environment," said Superintendent of Schools Elliott Landon.

However, since the school was built in the 1930s, and is full of plaster, the work has been "a challenge," Landon said.

Two additions have been built at the school, one in the 1960s and one in 1994. The two oldest sections are serviced by window air-conditioning units, while classrooms in the '94 addition are serviced by unit ventilators, which can be noisy.

The new HVAC system, according to Harris, will consist of a "chiller" behind the school, and a ventilator, about the size of a boxcar, on the west wing roof, which will allow fresh air to be "ducted" through all areas of the three-story building, she said. The system will also be computer-controlled and there will be individual temperature sensors for every room. The heating/cooling range of each room will be set somewhere between 68 to 72 degrees Fahrenheit.

The humidity controls will allow for a "higher comfort level" for students and teachers alike, said Harris, who noted research has shown people are most comfortable at a 45 percent humidity level.

"This will be the only school with humidity control and CO2 sensors," she added.

The project, which may "cost us a little more" than initially planned, according to Harris, must be completed by Sept. 12. The projected cost may rise because the cafeteria, gymnasium and auditorium will also be serviced by the system, and none of those large spaces are temperature-controlled at this time, she said. However, the district has applied for a state energy grant to help mitigate those costs.

"The critical piece was to bring in tempered fresh air into all areas of the building," said Harris. "That was our mission."