How Does Insulation Work?
Cool in Summer and Warm in Winter
Insulation basically prevents the loss of heat to the outside from your home during the winter and prevents the hot air from entering your home during the summer months. This is because insulation placed in the floors, attics and walls resists heat flow and prevents hot air from entering your home during the summer. (See Performance section)
Heat flow is a critical element in your energy usage. Heat naturally moves from warmer places to colder places. In winter, the heat produced by your heating system naturally moves from the warm home interior into the unheated spaces such as attics, garages, basements or directly outdoors. To compensate for this, your heating system must run more often to keep the home’s temperature constant. In summer, when the outside temperature is warmer than the interior of the home, heat will flow into your home making your air-conditioner work harder to keep the house cool.
By correctly installing the appropriate amount of insulation, this heat transfer can be reduced, due to insulations’ heat flow resistance, and thereby saving you money on your utility bills.
The most common measure of performance is R-Value but this is not the only measure that should be taken into account when preparing to insulate your home or business. For more information, refer to the WHAT DOES R-VALUE MEAN? in this section.
Sound Control
Insulation provides more effective sound control than dry-wall alone. Many people only focus on the heat resistant properties of insulation but overlook the benefits that come from improved sound insulation.
If you have ever walked into a house that is not insulated, you will immediately notice that noises from outside of the house are “louder” than in an insulated home.
There are two principal measures of sound control: Noise Reduction Coefficient (NRC) and Sound Transmission Classification (STC).
Noise Reduction Coefficient (NRC)
This value represents the amount of sound energy absorbed when a surface is struck. A value of 0 suggests the total amount of sound energy was reflected while a value of 1 suggests the entire sound energy was absorbed. This measurement is scalar and measures sound absorption coefficients at 250, 500, 1000 and 2000 Hertz.
For example, a building material with a NRC of 0.75 will absorb 75 percent of the sound that it comes in contact with. If you want to minimize the noise from a laundry room to an adjacent room, you want a value close to 0 so the sound is “kept in the room”.
Sound Transmission Classification (STC)
This value represents the amount of sound energy that is prevented from penetrating from one side of a material or wall structure to the other side. The higher the value, the greater the amount of sound energy that does not penetrate. For example, a STC rating of 60 should not allow high speech to be audible on the other side of a wall. STC measures frequencies ranging from 125 to 4000 Hertz.
Drywall and lumber have low STC and high NRC ratings compared to walls or ceilings with insulation in them. Adding insulation is the most cost-effective and efficient way to minimize sound transmission between rooms (if the interior walls are insulated) or from the outside.
FTI’s Cellulose Insulation has an STC between 45 and 68 and a NRC rating between 0.75 and 0.82 depending on wall design and construction, material and installed density. These values are much higher than fiberglass and foam insulations.
