subject: Insulation To Save On Air Conditioning And Heating Bills [print this page] In simplest terms, insulation is the prevention of heat transfer to and from a building. Therefore, with the proper insulation, a building is protected from unwanted heat loss or gain, keeping it warmer and cooler respectively, and reducing the burden on heating and air conditioning systems. Insulation can refer to both insulation materials having poor thermal properties, as well as specific designs and techniques to prevent heat loss through the modes of conduction, convection and radiation. The amount of insulation a building requires depends on budget, design, climate, energy costs, and personal preferences.
Some of the insulation materials commonly used to prevent heat transfer are:
1. Spray Polyurethane Foam (SPF) - Is a rapidly-expanding foam, a mixture of two components that is sprayed through a gun onto concrete slabs, wall cavities, interior side of sheathing, etc. Blocks airflow and acts as vapor barrier. Comes in different types such as Icynene, Polyicynene, Polyisocyanurate, closed and open-cell Polyurethane, Polystyrene, etc. There are some concerns regarding toxicity of materials.
2. Insulating concrete forms (ICF) - They are modular units that are stacked without mortar and filled with concrete, locking together like Lego bricks to create a form for the structural walls or floors of a building. ICF forms are built of Polystyrene, Polyurethane, and cement-bonded wood fiber or Polystyrene beads.
3. Batts and blankets - These are made of flexible fibers, most commonly fiberglass, but can also be made from mineral (rock and slag) wool, plastic fibers, and natural fibers such as cotton and sheep's wool. This is the most common form of insulation used in domestic buildings, but finds little industrial and commercial use.
4. Cellulose - This plant fiber is the oldest of all building insulation materials. Available as dry cellulose, spray applied cellulose, stabilized cellulose and low dust cellulose, and applied to different parts of the building for specific reasons. Cellulose insulation is superior to fiberglass and cheaper than SPF, and has often been claimed to save homeowners 20 to 50 percent on their utility bills.
5. Radiant barrier - Radiant barriers or reflective barriers prevent heat loss though radiation. Its constituent materials must have low emissivity at the wavelengths at which they are expected to function. For typical building materials, the wavelengths are in the mid- and long-infrared spectrum in the range of 3 - 15 micrometers, the usual wavelength for terrestrial radiation.
Some of the insulation designs and techniques commonly used to prevent heat transfer are:
1. Weatherization - Weatherization refers to the protection of a building from the elements, and mainly addresses the issue of heat loss through convection whereas thermal insulation concentrates on conduction. Typical weatherization procedures include sealing cracks, vents and ducts that allow air to flow in and out of the building.
2. Thermal bridge reduction - A building envelope marks the separation between a building's interior and the exterior environments. Thermal bridges are points in the building envelope that allow thermal conduction to occur. This can be minimized by reducing the cross sectional area of the bridges, increasing the bridge length, or decreasing their number.
