No, it’s not part of the Tron set, it’s what’s eventually going to be embedded in our concrete floors. As you can see from the photos, all the Pex tubing for the radiant heating system is in place, along with the rough plumbing. When the house is complete, the heat pump will heat water that will run through the tubing and warm the concrete slab floor (and the rest of the house). We noticed that Ted and crew were very careful to map out the rooms of the house and not run tubing under any areas we won’t want heat, like where the refrigerator and kitchen cabinetry will go. Under the black plastic, and just visible around the inside edges of the foundation, is rigid foam insulation, which will help keep the heat where we want it, in the slab. Next step: pouring the concrete.