Your home's secret money-saver

Jeffrey Anderson | Improvement Center Columnist | September 15, 2014

Utility costs can become a big chunk of your monthly budget - especially if you happen to live where temperatures in the summer or winter get extreme. But something in the walls is already saving you money, and could be saving you even more. Adding insulation is one of the easiest ways to increase your home's energy efficiency. How much could it save you, you ask? The government's Energy Star website estimates that a typical family in an average sized home could save up to 10 percent on their annual energy costs by sealing off points of air intrusion and installing more insulation. It's just a matter of knowing what type of insulation to use and where it should go.

R-values and your home's outer energy envelope

Before choosing an insulation, it may be helpful to know a little bit about R-values and your home's outer energy envelope. (We promise not to give you math class flashbacks.)

Each type of insulation comes with an R-value. Simply put, the higher the R-value, the more protection the material can provide your home. R-value is a measurement of a material's ability to resist the flow of heat through it. The value can vary from one material to another depending on its thickness or density.

When heating or cooling your home, there are barriers that prevent the conditioned air from escaping and un-conditioned air from the exterior finding its way in. These barriers are considered your home's outer energy envelope and are often made up of assemblies or a combination of materials, including an exterior siding, sheathing, insulation, an interior finish material, and the framing. The R-values of each material in the assembly are added together to arrive at the total R-value for that part of the homes outer envelope.

There should also be a barrier in your home's attic area and basement or crawl space. Windows and doors that face the elements also count here.

What type of insulation and how much?

You may think that buying the highest R-value insulation is the best way to keep your home energy efficient. But before you go calling insulation contractors, we've got some news. Where your home is actually determines how much R-value is recommended. To make it easy, the U.S. Department of Energy and the North American Insulation Manufacturers Association have charts on their websites that break the country down into regions. Each region then has a recommended R-value for the various components of a typical home's outer energy envelope. What types of insulation can be used for the components to achieve the recommended R-values? Here are the most common types:

  • Fiberglass batts - When most people think of insulation, this is the type that normally comes to mind. Fiberglass batts are available in a multitude of R-values and are usually fairly easy to install - even for homeowners who lack DIY skills. Batts are usually used in exterior walls, basements or crawl spaces between the floor joists, or in the attic between roof trusses. Batt widths are available for most common framing spacing measurements.
  • Blown-in insulation - Blown-in insulation gets its name from the method by which it's installed, which is usually through a large hose that originates from a specially equipped truck. The material may be fiberglass or cellulose, and the R-value is then determined by the depth of the insulation. Blown-in insulation is often the easiest way to increase the insulation levels of an unfinished attic where the floor makes up the outer energy envelope barrier. This material is also used to increase the energy efficiency of older homes with wood siding that may have little or no insulation installed in their exterior walls. Drilling small holes that can later be plugged allows the insulation to be blown into the framing cavities. Blown-in insulation is also available in bags that can be installed by homeowners.
  • Spray foam - This type of insulation is sprayed into place and then gradually hardens to form a protective layer. For larger jobs, the material is normally installed by a contractor with specialized equipment, but spray foam is also available in small containers for homeowner applications. Two advantages of spray foam insulation are: 1. High R-values can be achieved with less thicknesses than most other types of insulation, and 2. It's installed in a semi-liquid state, so it can flow into cracks and crevices often difficult to reach with blown-in or batts. Spray foam is often ideal for adding insulation to attics or crawl spaces. It's also great for exterior walls that have had their inner or outer finishes removed to allow access.
  • Insulation board - A lot of different materials fall into this category, but in most cases these are 4' x 8' sheets of various thicknesses that can be installed to add a little additional R-value to an outer envelope barrier. The most common use is on the exterior walls of a home prior to siding being installed.

All of these materials can be used to increase the energy efficiency of your home, which should help lower your utility costs. Where you plan on installing the material and whether you want to use a contractor for the application usually determines which is your best choice, but use your EnergyStar resources to help make the best decision for your home. Getting it installed before very hot or cold weather comes in could help you get through the season more comfortably - and save money while you're at it.

About the Author

Jeffrey Anderson has a Degree in English from V.M.I., and served as an officer in the Marine Corps. He worked in Residential and Commercial construction management for 25 years before retiring to write full time. He spends his time writing, remodeling his old farmhouse, and in animal rescue.