Insulation of Walls in a Solar House

Solid Wall Insulation

• In older homes, solid masonry walls can lose up to 35 percent of the home's heat, and adding insulation to the interior or exterior can help reduce energy bills by up to 25 percent. To insulate the exterior, attach standard insulation boards between 2 and 5 inches thick to the outside walls with adhesive. Finishing with a reinforced cladding material will make the total insulation 3 to 6 inches thick. Insulate solid walls on the interior by gluing a layer of insulation 2 to 5 inches thick against the inside of the walls and covering it with plasterboard.

Trombe Solar Walls

• In a technique invented by French engineer Felix Trombe, part of the wall is made of poured concrete and then covered with glass, leaving 1 to 3 inches of space between the surfaces, which creates a cushion of air between the two surfaces, minimizing the passage of heat through the walls. In winter, the glass helps to trap the solar heat, which warms the thermal mass of the concrete walls. Double-glazing increases the efficacy of the walls.

Water Walls

• A water wall makes use of water as a thermal mass in a passive solar home. Build a water wall using water in containers such as plastic or steel, or in tanks that can be stacked to create a wall. The most common use is to build containers of water into the space between two surfaces of wall or to mount metal tubes filled with water inside the wall enclosure. You can use water wall bags for a low cost option to store volumes of water. Water walls work particularly well in industrial and outdoor applications because appearance is less of a requirement.

Air/Vapor Barrier Walls

• Air filtration causes up to 40 percent of heat loss from a house, even if well insulated, while moisture can cause the deterioration of the wood and other materials used in the building. An air/vapor barrier prevents both air and moisture from passing through the wall cavity and helps to lower heat loss and energy bills. Install an impervious membrane in a continuous layer on the interior surface of the outside walls and ceilings, ensuring that there are no breaks in the membrane. Seal the joints with compressible rubber for a completely airtight result.