A precast concrete panel and method for forming the panel are disclosed. A method of forming the panel to be used as a floor, wall, or roof structure includes positioning one or more forming members within a casting bed having a plurality of upright surfaces defining a generally rectangular interior area, the one or more forming members comprising an insulating material extending along a length dimension of the one or more forming members to define a plurality of rectangular-shaped channels in a parallel and spaced-apart relationship, placing uncured concrete within the casting bed and allowing the concrete to cover the one or more forming members and substantially fill the channels, and allowing the concrete to cure.

A structural insulated building unit is provided for constructing a building. The structural insulated building unit includes an insulating core, first and second cementitious panels, and a connecting portion. The insulating core is defined by multiple sides and opposing first and second faces. The first and second cementitious panels are coupled to the first and second faces of the insulating core. The connecting portion is provided on one of the sides of the insulating core, and aligns the structural insulated building unit with an adjacent structural insulated building unit having a complementary connecting portion when constructing a building.

The present invention provides a modular insulated concrete wall panel system comprising at least one assembled panel, each assembled panel comprising a precast concrete panel and one or more insulation panels. The concrete panel has an outer frame and plurality of vertical ribs that engage with corresponding channels on the insulation panels. There is also provided a method of forming a modular concrete wall panel system of the present invention, comprising the steps of: providing the at least one preformed insulating panel laid horizontally with the vertical channels facing in an upward direction; pouring concrete around the at least one preformed insulating panel such that the concrete fills the channels in the insulating panel, thereby forming the concrete panel rib elements; and allowing the concrete panel to set and cure.