As the renovation and expansion of the McIlvaine Early Childhood Center gets fully underway, another sort of construction is taking place deep underground, behind the school.

    McIlvaine will become the first public school in Kent County to be heated by geothermal wells – 130 of them, in fact.

    Over the next few weeks, workers will continue drilling boreholes down approximately 300 feet to lay out the well field, which connects by pipes and eventually feeds into the school building through two, eight-inch pipes. The entire system will lie at least four feet underground.

     Andrew Weber, owner of Weber Well Drilling of Dagsboro, said the easiest way to explain the system is that it acts like a radiator.

    In the summer, as heat infiltrates the building, pumps collect that heat and transfer it deep underground, via an anti-freeze fluid, he said. That warms up the overall ground temperature slightly, perhaps going up to the upper 80s, he added.

    Then in the fall, the system is switched around so that stored heat can be pulled up from the ground to the building, Weber said.

    It works the same as when the sun heats a rock in the desert and that rock is still hot at night, he said. The ground retains heat like the rock would, but instead of just transferring heat by day and night, it transfers heat by seasonal cycles.

    “It takes a year or two to get up to peak efficiency,” he said of the heat transfer process.

    The efficiency of the system depends on the type of soil, which could account for a 20% difference in the number of wells that need to be installed. For commercial projects, Weber said conductivity tests determine what that number should be.

    The efficiency of geothermal heating also translates into savings.

    Dan Booze, a Baltimore geothermal consultant with Gipe Associates, who designed the well field, said there’s usually an immediate payback.

    Speaking in general terms on any school geothermal project on the Eastern Shore, he said the project should cost approximately the same as installing a conventional heating system. Although residential geothermal projects still cost more than conventional heating, that’s not the case with tough competition and the large-scale size of school projects.

    Operating costs also are much lower. Booze said he’s seen studies where it costs $1.30 per square foot to conventionally heat a school per year, but with geothermal it’s 90 cents to $1.10 per square foot.

    “That’s a huge draw for owners when they are looking at operating costs,” he said.

    Booze said in the past seven years, he’s consulted for 30 to 40 schools that were putting in geothermal systems. Geothermal business also is up for Weber, who said it accounts for 90% of his business and he’s drilled 10 schools in the past three years.

    Caesar Rodney supervisor of facilities management Kevin Thompson said he knew the district needed to take a serious look into geothermal heating when he visited a school in Salisbury, Md.

    It was one of the coldest days of the year last winter, he said, and when they went into the finished part of the building, which was still under construction, he could feel heat instantly.

    “I thought, ‘This is something we need to do,’” Thompson said.

    The McIlvaine school will have only electric costs for some of the pumps that move the air around the building — no more high natural gas or oil bills, he said.

    Weber said the McIlvaine system is self-supporting because it runs in a closed loop, which doesn’t require any fluid to be added. Basic geothermal technology has been around for 40 to 50 years, he said, but the closed loop system is approximately 10 years old.

Email Jayne Gest at jayne.gest@doverpost.com