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Reducing Energy Costs with Insulation

04/22/2008 by RSMeans Engineering Staff

Heating or cooling your home or office accounts for a large portion of your total energy use. As utility costs skyrocket, facilities managers and homeowners will be looking to find ways to save energy and money. Insulation will be one of the methods.

Insulation restricts the flow of air. Warm air will naturally try to move to a cooler area. By placing insulation around the conditioned space, you are attempting to limit or slow down this natural movement. The amount of restriction or slowing down is measured by the R-value of the material being used. The higher the R-value, the higher the amount of resistance to air flow. The R-value is dependent upon the material’s thickness and density.

Each of the commonly used insulation materials has its advantages and disadvantages, but they also have attributes that are required by the specific installation location or technique. Some of the most common types are discussed below.

Fiberglass blankets are probably the most recognized form of insulation materials. Rolls or slabs of glass fibers come in many thicknesses and colors. Easy to install and relatively inexpensive, fiberglass insulation also has the advantage of being produced with 20 to 30% of recycled industrial waste and post-consumer content. Fiberglass also comes in rigid board and loose fill form for other applications.

Mineral wool blankets are made from rock, slag from blast furnaces or recycled glass. It is generally more resistant to airflow than fiberglass.

Insulation materials such as cellulose, mineral wool and fiberglass can be blown in place with air powered equipment. The advantages of blown-in insulations are:

  • Works well in irregularly shaped areas
  • Works well for filling in around obstructions
  • Can be combined with adhesives for vertical and overhead horizontal applications

Foam board insulations, such as polyisocyanurate, extruded polystyrene and expanded polystyrene are easy to use and install. They are generally available at home centers and though insulation suppliers. Reflective laminates are often included with the foam for even greater resistance to heat flow. Foam board insulations are used for exterior wall sheathing and foundation wall insulation.

Sprayed foam insulations require professional installation. Expensive equipment is required to mix and deliver two liquids to a spray nozzle. Once mixed at the spray nozzle, a chemical reaction causes the liquids to solidify and expand. This expansion allows the resultant foam to fill all the voids and cavities into which it is sprayed. The result is a completely filled cavity with few voids or breaks even around wiring or pipes that may be in the cavity.

Reflective insulations and radiant barriers are typically made from aluminum foils with a paper, plastic or cardboard backer. They work by reflecting heat flow rather than by impeding it.

Each of the types of insulation mentioned above has characteristics that allow their use in many different applications. Architects and engineers will choose the best possible insulation for the specific installation based upon these characteristics.


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