Since the early 20th century, many homes and buildings have been constructed using cavity walls. This means that the exterior walls of the home are separated from the interior walls by an empty space, or cavity. This cavity is usually just a few inches wide, and up until the end of the 20th century, this space was left empty. As the green building movement has gained momentum, the idea of adding insulation to this cavity became a popular way to save energy. Today, insulation in exterior walls is fairly standard, and many homeowners are adding spray foam insulation to their existing walls in order to enjoy its many benefits.
Lower Utility Bills The US Department of Energy calculates that heating and cooling costs account for between 50 and 70 percent of most people's monthly energy bills. By lowering your heating and cooling needs, you can significantly reduce your utility bills. According to the UK Energy Savings Trust, homes with no exterior insulation lose about one-third of their heat through the walls. This means that around one-third of the heat you pay for in your monthly utility bills is escaping to the outside, rather than heating your home. In homes with cavity wall insulation, the heat is kept inside, meaning less waste and lower bills. The US Department of Energy's "Energy Star" agency suggests that adding insulation can reduce monthly energy costs by up to 20 percent, depending on the climate in your region.
Improve Comfort By adding cavity wall insulation, you can help maintain a consistent, comfortable temperature in the home. Extreme hot or cold air from the outside will be unable to penetrate your home, which means a more moderate temperature level year round, as well as fewer drafts. With insulation keeping air contained in the home, you can set your thermostat at the desired level and know that the home will stay close to this level. Because no air can leak out, you will not find yourself constantly adjusting the temperature setting in an attempt to get comfortable.
Reduce Moisture Problems Many homes are loosely built, which means that air and moisture can easily leak into or out of the home. While air may cause discomfort and higher utility bills, moisture infiltration can cause more serious problems. By using cavity wall insulation, you are taking away one of the largest paths that humidity, precipitation, rain, and condensation usually take to enter the home. By blocking these moisture sources, you can help prevent problems with mold, mildew, rot, and other potential issues.
Additional Benefits Exterior-wall insulation also offers a variety of lesser known benefits to homeowners. Because it is placed inside the walls, it helps protect the pipes in these walls from freezing or bursting. Insulation also acts as a barrier to sound transmission, helping to reduce the amount of street or neighbor noise you can hear from inside the home. Finally, insulation can sometimes help slow the spread of a fire by keeping outside air from entering the home. This is especially true of insulation products designed specifically for fire-safety.