Insulating Concrete Forms are exactly that. They INSULATE the concrete that is used to form the structure of your home. The polystyrene is on both sides of the concrete, the interior and exterior of every wall in the home. This provides for an extremely high R-Value (the measure of insulating ability.) The R-value for walls made of Insulating Concrete Forms range from R-17 to R-26. this compares to the R-Value of a wood framed home being only R-9 to R-15.
Walls constructed of Insulating Concrete Forms and concrete also have a high thermal mass. This means that the interior of a home doesn't experience as large of a temperature swing between cool nights and hot days. This reduces the heating and cooling loads on the house. It is possible for homes made of Insulating Concrete Forms to have a 25%-50% energy saving compared to homes built of wood framing.
Because the walls are made of a continuous pour of concrete, homes built using Insulating Concrete Forms have far fewer construction joints. Every time there is a construction joint where build elements come together (siding, sub-flooring, studs etc.), it increases the places where outside air can infiltrate the home. Less outside air penetration means a reduction in heating and cooling, saving you money.
In conclusion, homes made of Insulating Concrete Forms reduce your heating and cooling utility bills in the long run. For an immediate savings, the heating and cooling system of your home can be downsized from that of a typical wood frame home. This downsizing can save you hundreds or thousands of dollars for construction.