If you're a homeowner, one of your greatest ongoing expenses is probably your heating and cooling bill. You'll certainly want to reduce this expense in any way you can, such as by installing a modern, energy-efficient heating and cooling system or hiring heating repair to fix your current system. But regardless of how efficient a system you have, if you have a poorly insulated, leaky home, your energy dollars are just floating off into the air. The key to solving this problem is choosing the right insulation and having it properly installed. But to do this you need to understand insulation, including the somewhat abstract concept of R-value. R-value is the feature of insulation that defines its ability to resist the flow of heat into or out of your home. The following will help you understand the importance of R-value and how to choose the right insulation for your home.
The R-value of a material is defined by a number ranging from R-1 to R-60. While most people think of R-values as being applied only to insulation, all building materials have an R-value. This R-value is tied to the material's density and thickness. For instance, 3 inches of cellulose insulation will have a very different R-value than 3 inches of fiberglass insulation. Within most types of insulation, you can find a range of densities. Each of these will have their own particular R-value per inch.
Common Types of Insulation
In the United States, the most commonly used type of insulation is fiberglass. Fiberglass insulation usually comes as batts (or blankets). Fiberglass batt insulation generally has an R-value of around 2.5. Higher density polystyrene panels can have an R-value up to 4. Cellulose insulation (a type of loose fill insulation) is usually made from recycled newspaper or similar materials and has R-value of just over 3. Keep in mind though that you can achieve higher R-values with any material simply by using a thicker layer of it.
Difference between Rated and Effective R-Values
Any insulation material you install will come with an R-value that has been assigned by the manufacturer. This value is based on the assumption that the insulation will be properly installed. However, if there are gaps in the insulation, this can significantly reduce the effective R-value. Effective R-value is what determines the energy savings you will realize, not the rated R-value. In addition to the problem of caps and leaks, loose fill insulation has a tendency to settle and compress over time, which can negatively affect its R-value.