insulate

Insulation in your home provides resistance to hot and cold air flow. The more of your conditioned air flow resistance your insulation provides, the lower your heating and cooling costs will be. Properly insulating your home not only reduces heating and cooling costs, but also improves your homes comfort level.

HOW INSULATION WORKS

To understand how insulation works it helps to understand how air flows, which involves three basic mechanisms — conduction, convection, and radiation. Conduction is the way heat moves through materials, such as when a spoon placed in a hot cup of coffee conducts heat through its handle to your hand. Convection is the way heat circulates through liquids and gases, and is why lighter, warmer air rises, and cooler, denser air sinks in your home. Radiant heat travels in a straight line and heats anything solid in its path that absorbs its energy.

Most common insulation materials work by slowing conductive hot or cold air flow and to lessen the extent of convective air flow. Radiant barriers and reflective insulation systems work by resisting the transfer of two temperatures. To be effective, the reflective surface must be installed to the outer surface of the of the conditioned area.

Regardless of the mechanism, heat flows from warmer to cooler until there is no longer a temperature difference. In your home, this means that in winter, heat flows directly from all heated living spaces to adjacent unheated attics, garages, basements, and even to the outdoors. Heat flow can also move indirectly through interior ceilings, walls, and floors — wherever there is a difference in temperature. During the cooling season, heat penetrates the home from the outdoors to the interior of a house causing high humidity and uncomfortable living space.

To maintain comfort, the heat lost in the winter must be replaced by your heating system and the heat gained in the summer must be removed by your cooling system. Properly insulating your home will decrease this heat flow by providing an effective resistance to the flow of heat, ultimately reducing the run time of your heating and air conditioning system and saving you money.

R-VALUES

An insulating material’s resistance to conductive heat flow is measured or rated in terms of its thermal resistance or R-value — the higher the R-value, the greater the insulating effectiveness. The R-value depends on the type of insulation, its thickness, and its density. When calculating the R-value of a multilayered installation, add the R-values of the individual layers. Installing more insulation in your home increases the R-value and the resistance to heat flow. To determine how much insulation you need for your climate, consult one of our professionals.

The effectiveness of an insulation material’s resistance to heat flow also depends on how and where the insulation is installed. For example, insulation that is compressed will not provide its full rated R-value. The overall R-value of a wall or ceiling will be somewhat different from the R-value of the insulation itself because heat flows more readily through the wooden studs, joists, and other building materials, in a phenomenon known as thermal bridging. In addition, insulation that fills building cavities densely enough to reduce airflow can also reduce convective heat loss.

Unlike traditional insulating materials, radiant barriers are highly reflective materials that re-emit radiant heat rather than absorbing it, reducing cooling costs. As such, a radiant barrier has no inherent R-value. Although it is possible to calculate the effectiveness of these systems which lies in their ability to reduce heat gain by reflecting heat away from the living space.

The amount of insulation or R-value you’ll need depends on your climate, type of heating and cooling systems, and the part of the house you plan to insulate. To learn more, ask one of our professionals what application methods may be best suited for your home. Also, remember that air sealing and moisture control are important to home energy efficiency, health, and comfort.

TYPES OF INSULATION

To choose the best insulation for your home from the many types of insulation on the market, you’ll need to know where you want or need to install the insulation, and what R-value you want the installation to achieve. Other considerations may include indoor air quality impacts, life cycle costs, recycled content, embodied energy, and ease of installation.

INSULATION MATERIALS

Insulation materials run from bulky fiber materials such as fiberglass, rock and slag wool, to soft smooth materials such as cellulose, and easily cut and shaped products such as rigid foam boards to sleek foils. Bulky materials resist conductivity, rigid foam boards stop air flow while added insulating properties, highly reflective foils in radiant barriers and reflective insulation systems reflect heat away from living spaces, making them particularly useful in cooling climates. Other products such as expanding 2 part polyethylene spray foam can be especially affective in blocking air and has a much great heating resistance than other common insulations.