Energy efficient livestock buildings can be made by combining the advantages of concrete, earth and solar heat. Solar collectors gather the heat from the sun's rays, earth acts as a temperature shock absorber and concrete acts as a heat sink. With its large heat storage capacity, concrete like earth will not change temperature at a rapid rate. Consequently, it takes a long time for drastic temperature swings to reach the inside of a concrete building, especially if it is earth sheltered.
Hogs cannot eat concrete, and rodents cannot eat through it. Fire does not burn it, and water does not warp or rot it. Animal pens can thus be easily spray cleaned. Concrete does not need to be painted, and it does not need outdoor siding or eventual re-siding. Concrete lasts, and because it does, life cycle costs are low. Benefitting from these advantages are two earth-sheltered concrete hog farrowing houses built in Iowa, both also with solar collector systems. Concrete wall solar collectors can reportedly save up to 2 gallons of propane per square foot during a heating season.
The exterior walls of the farrowing house and nursery near Ridgeway are made of cast-in-place concrete 8 inches thick. The north, east, and west walls are 8 feet high, but due to the roof collector the south wall is only 4 feet high. The walls are insulated with 2-inch-thick polystyrene on the outside and are earth-bermed to the eaves. Where the walls are not earth covered, the insulation is protected with aluminum siding. The 60-degree south slope of the roof is covered with 4- or 6-mil polyethylene. Inside, concrete partitions subdivide the 100x28-foot building into farrowing pens.