Why Homes and Buildings Need Insulation

Air conditioning and heating systems are the biggest energy use in most homes, and energy has become a lot more expensive over the past few decades. As energy has become more expensive, it has become more desirable to reduce the amount of energy consumed to keep indoor spaces at a comfortable temperature. There are three ways to achieve this goal:

Keep the indoor air temperature warmer during the summer and cooler during the winter.  A good rule of thumb is that every degree change in thermostat setting changes air conditioning and heating system energy consumption by about two percent. For example, if you normally keep your air conditioner thermostat at 76 degrees during the summer and you change the setting to 78 degrees, you would expect to reduce your summer cooling costs by about four percent. Of course, this approach may reduce your comfort. One compromise is to invest in a programmable thermostat, which can change temperatures to save energy during periods when you are typically not at home.

How it saves money:  Automates daily changes in temperature settings.
Cost of a good programmable thermostat:  $200 to $300.1
Long-term costs:  A good programmable thermostat should last indefinitely with no additional costs.
Potential energy savings:  5% of annual electric costs.2
Indoor air quality improvement:  None.

Invest in a more energy efficient central air conditioning system.  You may benefit from replacing your air conditioning system, especially if it is more than seven years old. An air conditioner’s efficiency is usually rated by SEER, which stands for “Seasonal Energy Efficiency Ratio.” A more efficient air conditioning system has a higher SEER, which means lower electric bills. Air conditioners installed 10 or more years ago may have a SEER of 10, or even less if the unit is no longer working at its design efficiency. Current building codes require air conditioning systems with a minimum SEER of 13, which will use about 23% less energy than an older 10 SEER system. A high efficiency heat pump with a SEER of 16 uses about 38% less energy than a 10 SEER system.

Some air conditioning equipment manufacturers and big box building supply stores advertise greater savings, but the greater savings assume a SEER of 0, which is not realistic. Any central air conditioning system installed during the last 20 years has a SEER of at least 10.

How it saves money:  Newer compressors are more efficient.
Cost of a new three-ton high efficiency heat pump central air conditioning system:  $5,000 to $8,000.3
Long-term costs:  $100 to $200 every two to three years for maintenance; $1,200 to $1,500 every 7 to 10 years for a new compressor; and complete system replacement every 15 to 20 years.
Potential energy savings:  12% to 19% of annual electric costs4
Indoor air quality improvement:  None.

Improve the thermal efficiency of your walls and attic.  Your home will use less energy for cooling and heating if it is well insulated because your air conditioning system won’t have to work as hard, no matter what its SEER is. And with a really well insulated home, you might even be able to achieve the same comfort level you are accustomed to with a smaller air conditoning system. Frankly, you should always consider upgrading your home’s insulation before you consider replacing your air conditioing system, for several reasons:

As you can see above, when you invest in upgrading your home’s insulation, you can potentially gain many benefits that go beyond just lower electric bills. Most of these added benefits are only available when you install foam insulation. The traditional insulation materials that have been used for several decades, fiberglass and cellulose, are porous and don’t stop air infiltration.

How it saves money:  Blocks outside air infiltration. Plus, even if expected R-values are the same, the actual R-value of existing fiberglass insulation is reduced by imperfect installation and settling over time.
Increasing wall and attic insulation:  $2,500 to $9,500.5
Long-term costs:  None for correctly installed foam insulations. For fiberglass and cellulose, replacement or added insulation may be advisable after 15 to 20 years.6
Potential energy savings:  1% to 5% of annual electric costs for fiberglass or cellulose; 10% to 20% for foam insulations.7
Indoor air quality improvement:  Dryer, cleaner and healthier air for foam insulations, which block air infiltration. None for fiberglass or cellulose, which are porous.

/* Calculate ratio of wall area to roof area for air infiltration. */

Sealing air leaks around your home and adding insulation can make your home more comfortable, quieter and more energy efficient. You could save about 10% on your annual energy bills if you have a new home, or as much as 50% for older homes lacking meaningful insulation.

Complete Thermal Enclosure System

Comprehensive air sealing, properly installed insulation, and high–performance windows work together to enhance comfort, improve durability, reduce maintenance costs, and lower monthly utility bills.

Air Sealing

By using less energy for heating, cooling, and water heating, ENERGY STAR®certified homes deliver approximately 20% savings on annual utility bills. Over the 7 to 8 years that a typical family lives in a home, you can save thousands of dollars in maintenance cost.

Properly Installed Insulation

It’s not just the amount of insulation; it’s the quality of installation that makes all the difference. Proper installation includes careful placement to eliminate gaps, voids, and compression; complete air barriers that prevent air from bypassing the insulation; and building techniques that minimize heat flow through framing. This ensures consistent temperatures throughout the house, reduced energy use, and increased comfort.


You want your home to be comfortable no matter what room you’re in or what the weather is outside. Comprehensive air sealing, properly installed insulation, and high-performance windows work together to deliver better comfort, better durability, reduced maintenance costs, and lower monthly utility bills. A comprehensive thermal enclosure system:

Sealing to Minimize Air Infiltration

A typical home has about half a mile of cracks and gaps behind walls and around windows and doors, and dozens of holes for pipes, vents, ducts, lighting and wiring. Sealing these openings with a comprehensive air sealing package helps to significantly reduce drafts, moisture, dust, pollen, pests, and noise. The best time to seal these is during the construction process because access to critical areas can be limited once the house is completed.

You could try to seal these cracks, gaps and holes with caulks, gaskets and sealing strip products. But common sense has to tell you that locating and sealing a half mile worth of cracks and gaps is impractical at best and impossible at worst. There is a better way. Spray foam insulation automatically expands in your wall spaces and under your roof deck when applied, fiowing into the smallest and most irregularly shaped openings—even the openings you can’t see.

One great example of this is found at the attic access panel, ENERGY STAR®certified homes feature a gasket to create a tight seal around the panel. This is a detail that is commonly missing in many other homes and can have a real impact on your comfort and utility bills.

The energy savings from comprehensive air sealing can quickly add up when you consider all the places hot or cool air can enter or escape from your home. Having a well sealed home also means better air quality because dirt, pollen, pests, and moisture can’t get in as easily. A tightly sealed building envelope also protects the structure and occupants against mold and moisture damage, which are promoted by condensation of maisture in air pulled into the house by pressure differences between the indoor and outdoor air.

Thermal Bridging in Exterior Walls and Roof Structure

Walls in homes are typically built with wood studs, which support the weight of the floors and roof above, help the home stand up to wind, and generally act as the structural “bones” of the home. While these components are critical to making a durable home, they often have a very low R-value (resistance to heat flow) and create thermal “bridges“—uninsulated pathways that compromise the comfort and efficiency of the home. ENERGY STAR®builder partners select one of five strategies, such as adding a continuous layer of rigid foam or minimizing excess wood studs, to minimize thermal bridging in walls.

Proper Installation of Insulation

Insulation should be installed with minimal gaps or compressions and aligned with air barriers to improve performance. Imagine wearing a down jacket that’s two sizes too big on a winter day—the cold air would come right up under the coat and chill your skin. Insulation also needs to surround wires, plumbing and piping inside walls to not leave empty, uninsulated spaces that could lead to hot or cold spots. These practices help maintain consistent air temperatures throughout your house, reduce energy use, and improve comfort, especially on the hottest and coldest of days.


  1. Price does not include professional installation.
  2. Assumes cooling and heating costs are 50% of annual electric costs, and thermostat setting is raised by five degrees for cooling and lowered by five degrees for heating, to save energy during 50% of cooling and heating hours (for example, during the daytime hours typically spent away from home). The simple savings calculation is 2% per degree of thermostat setting change × 50% of total available hours × 50% of annual electric cost.
  3. Price range includes professional installation and a new 1,200 CFM air handler but may not include replacement of attic ductwork. A new air handler is almost always required to match the performance of the evaporative cooling coil (which is located inside the air handler) to the performance of the compressor condenser coil unit (the unit located outside the home). Expect to pay an extra $1,000 or so for every 2 units of increase in SEER (for example, from 13 to 15).
  4. Assumes cooling and heating costs are 50% of annual electric costs, and a 10 SEER central air conditioning system is replaced with either a 13 or 16 SEER system, with the 16 SEER system producing the greater energy savings.
  5. Installed price range for a typical 2,400 square foot home. Price varies greatly depending upon the type of insulation chosen and how much of the building envelope is insulated (for example, the attic only or attic plus exterior walls).
  6. Fiber insulations lose insulating value as a result of dampness and settling over time. Insulation soaked as a result of wind-driven rain through attic ridge vents or soffits should be replaced immediately.
  7. Minimum savings assume R-11 existing wall insulation and R-19 existing ceiling insulation, 2.9 COP/SEER 11 air conditioning system, and cooling and heating costs are 50% of annual electric costs. Attic and wall heat loads are 12% and 8% of total air conditioning system heat load, respectively. Heat and humidity load due to air infiltration is 28% of total air conditioning system heat load. Source: “Dealing with heat and humidity in Florida homes,” Florida Solar Energy Center, Energy Note FSEC-EN-14-86. Increasing attic fiberglass or cellulose insulation from R-19 to R-38 reduces heat load from roof by 13%, so 13% × 12% × 50% = less than 1% savings in annual electric costs. Insulating uninsulated exterior walls to R-11 reduces annual electric costs by 8% × 50% = 4%. Replacing existing R-19 fiberglass or cellulose attic insulation with 5 inches of spray foam insulation delivers the same R-value, but blocks attic air infiltration, which can be responsible for as much as 20% of the load on a home’s air conditioning system. If fiberglass or cellulose attic insulation is more than 20 years old or attic is not insulated, savings increase to ((79% × 12%)+(28% × 40%)) × 50% = 10%.