Homeowners can save about ten percent of their total energy bills by sealing air leaks first, followed by adding insulation. Weatherizing your home this way is one of the most cost effective ways to improve energy efficiency and comfort. You may save even more on your annual energy bills by completing an energy audit and making just some of the improvements identified in your home’s audit assessment.
Once you’ve sealed all air leaks, check your home’s insulation levels and add more where needed. Insulation blocks heat loss in winter and heat gain in summer, which lowers your energy use and makes your home more comfortable year-round. Learn more about the types of insulation available and tips that may lower your energy use.
Types of Insulation
Insulation materials are rated by an “R-value,” which indicates a material’s thermal resistance. The higher the R-value, the better the insulation. The four common types of insulation are:
- Batt or Roll Insulation – made from mineral fiber (either fiberglass or rock wool) in blankets of various sizes and thicknesses. Is generally installed between studs, joists and beams and should fit into the wall, floor or ceiling cavity without any gaps, voids or compression. This is the easiest product to install with the lowest cost. As a result, it is the most common type of attic insulation in Michigan. The down side is that it offers less R-value than cellulose or foam on a per inch thickness basis.
- Blown-in or Loose-fill Insulation – made from fiberglass, rock wool or cellulose in loose fibers or fiber pellets and is blown through a large hose into walls and attic spaces. Blown-in insulation is well suited for hard-to-reach places. Cellulose tends to have a higher R-value than fiberglass, is sound retardant, fire retardant, and repels insects. The price of cellulose insulation is similar to that of fiberglass.
- Rigid Foam Insulation – made from polystyrene, polyurethane, or polyisocyanurate foam manufactured in large sheets. Can be used to provide a continuous thermal barrier in basements, crawlspaces and exterior walls.
- Sprayed or Injected Foam Insulation – made from polyurethane or similar products and are injected or spayed into cracks or cavities where it expands to the desired thickness.
Save Energy Tips
Improve your home’s insulation and reduce your energy use by following these tips:
- The attic is the easiest and most cost effective place to add insulation. If the ceiling joists are exposed, more insulation should be added. If you have less than 6 or 7 inches of insulation in your attic, consider adding about 5 or 6 more inches to achieve an R-value between R-38 and R-60.
- If the attic access door is located above conditioned space, add the same amount of insulation as the attic and ensure the door closes tightly.
- Adding blown-in or loose-fill cellulose on top of batt or rolled insulation will increase the insulation value, or R-value, of your attic.
- Use higher density insulation on exterior walls, such as rigid foam insulation, if possible.
- If the exterior walls of your home are not insulated, have an insulation contractor add blown-in cellulose insulation to the walls.
- Use sprayed or injected foam insulation to seal air leaks where plumbing and wiring enter insulated areas.
- Recessed light fixtures can be a major source of heat loss. If you have recessed light fixtures, determine if they are IC rates fixtures, meaning they’re designed for direct insulation contact. Other types of fixtures allow large amounts of your heating and cooling dollar to escape into the attic.
- If you plan to finish your basement, insulation can help keep adequate warmth in a typically cooler area, thus using less energy to heat this additional living space. Be sure to follow required local building codes and Install a vapor barrier (rolled plastic sheeting) on BOTH sides of the insulation - 1 layer between the concrete and the back side of the stud wall, and a 2nd layer between the insulation and the heated space.
How much insulation is recommended?
Due to the 'diminishing returns' aspect of insulation (the higher the R-value goes, the less savings there is per R added), an attic with at least 6" of insulation - or a depth to at least 2" over the top of the ceiling joists, is considered to be adequate. Adding another 6" would be good, but does not save as much as the first 6" does. If the ceiling joists are exposed, then more insulation should be added.
It is more important, from a structural integrity standpoint, that an attic be properly ventilated than insulated. Of course, both depend on the other to function correctly. If the heat is not ventilated, it can build up on the underside of the roof causing snowmelt. As a result, water runs down the roof to the eave, where it typically is not over a heated attic, turning colder. The water then refreezes causing an "ice-dam" allowing water to back-up under the roof shingles causing leaks. The house can also be damaged from ice weight and falling ice.