In one multiphase project in western Massachusetts, the homeowners anticipate getting a 70 percent reduction in energy use by adding a layer of foam insulation on the roof and outside walls among other enhancements. Slashing energy use means lots of insulation: the roof will have an R-value, or insulating value, of 59, which is two or three times that of a typical New England home.Closer to Boston, a superinsulation project at an 85-year-old, two-family home in Arlington, Mass., was able to reduce the amount of heating oil by about two-thirds in its first year, according to homeowner Alex Cheimets. In that case, homeowners decided to seal and add insulation to the exterior of the home when they had to replace the aging shingles.Another project where only the roof was replaced and extensive air sealing done was able to reduce cut energy usage by 44 percent based on the same average heating days, according to David Joyce, the president of Synergy Companies Construction, who worked on the project.