A plurality of panel subassemblies are used to erect a building on a footing or foundation. Each panel subassembly includes at least one column formed of a thermally-insulating material, and a concrete portion at least partially attached to the at least one column. The concrete portion may be formed as a single precast unit. The panel subassemblies are secured together and to the foundation, and may be secured to a floor element of the building to at least partially support the floor element.