contents 1. Cavity Walls 2. Attics 3. Hot Water 4. Floor 5. Payback Calculation 6. Compare your Home`s Energy Performance 7. Environmental Insulation Costs 8. References

The cost of insulation is usually measured by the time to payback the initial cost of installation through energy savings. The cost is also measured in cost to human health and the environment for the production and consumption of the unnecessary energy expended as a result of insufficiently insulated buildings. In a typical house, 35% of heating energy is lost through walls, 30% through the roof, 20% through windows, and 15% through doors and floors.

Payback can be calculated by dividing the initial cost of insulation by the annual amount of savings in energy costs. Most agencies and manufacturers report the payback time on any insulation job as 5-6 years. Heavily insulating a building is a worthwhile investment of time and money as a building will stand for 100 years or more, even though time to payback can vary considerably based on fuel cost and initial installation cost.

During renovation is the perfect time to add additional insulation. Retrofit projects including blown cellulose in wall cavities, adding extra insulation to the attic floor and adding a radiant barrier to the attic ceiling give the biggest bang for the buck and are the easiest retrofits. Renovation projects like replacing the roof or the siding are also a good opportunity to add insulation.

Houses built in the 1930s or later have cavity walls. Cavity wall insulation reduces the heat loss through the walls by up to 40%. Un-insulated walls can be retrofit by blowing loose fill cellulose into the walls through holes in either the interior or exterior walls depending on what other renovations are taking place at the same time. For older homes with solid walls, insulate the interior and cover with drywall or insulate the exterior if you are changing the siding.

The Oxford City Council estimates that costs will be completely recovered for cavity wall insulation in 3-5 years while the Plymouth City Council estimates payback in less than 2. Insulating the inside wall will take 5-6 years to pay back and insulating the exterior will take 9-11 years to payback due to the cost of the siding.

Adding attic insulation is the most common retrofit insulation project. Insulating an un-insulated attic saves 25% in cold climates while adding a radiant barrier to an insulated attic saves 12% in warm climates. Attics are easy to insulate as a do-it-yourself project. The Oxford City Council estimates that the cost to add extra insulation to an attic currently without the correct thickness will pay back in 5-7 years if you install it your self. Adding insulation yourself to an un-insulated attic will pay back in 2 years.

Research conducted by the Florida Solar Energy Center (FSEC) has shown that the installation of a radiant barrier can have significant economic benefits. Attics account for approximately 22 percent of the heat gain in a typical Florida house. Installing an attic radiant barrier will reduce heat gain through the roof by about 40 percent. This equates to a savings of 8 to 12 percent on the annual electricity costs for air conditioning in a typical Florida home. The summer peak energy use savings was as much as 27%. This study also showed that the average peak reduction from the radiant barrier system was three times as great as that produced by added batt insulation (a change from R-13 to R-19).

Click here for a comprehensive article on Radiant Barriers.

Adding a hot water tank jacket can cut heat loss by up to 75% from your hot water tank. Use either six inches of batt insulation or foam core reflective insulation. Costs to insulate the hot water tank will be recovered in less than a year. Similarly, the cost of insulating hot water pipes will be recovered in 2 years.

If the underneath side of the floor is accessible through a basement or crawlspace, the Oxford City Council estimates that the cost of adding insulation will be recovered in 4-7 years. The Plymouth City Council estimates payback in less than 3 years.

The US Department of Energy (DOE) and local building code regulations provide guidance on the type and thickness of insulation required for various areas of a building. Beyond code requirements, additional insulation can reduce energy costs further. There is an optimum insulation level for each building area that will result in the lowest combined cost of initial insulation and energy for heating and air-conditioning over the lifetime of the house. Adding additional insulation will result in incremental energy savings that decrease with each additional inch added. An engineer can calculate this optimum insulation level for you precisely or you can use the DOE R-Value recommendation calculator by your zip code found at www.ornl.gov/sci/roofs+walls/insulation/ins_16.html.

The DOE provides the following calculation for years to payback.

See the DOE website article, "Estimating the Payback Period of Additional Insulation" for an example of the formula in use: http://www.eere.energy.gov/consumer/your_home/insulation_airsealing/index.cfm/mytopic=11360.

To calculate the payback, you must supply the following information:

• C(i) = Cost of insulation in $/square feet. Collect insulation cost information; include labor, equipment, and vapor barrier if needed.
• C(e) = Cost of energy, expressed in $/Btu.
• To calculate the cost of energy, divide the actual price you pay per gallon of oil, kilowatt-hour (kWh) of electricity, gallon of propane, or therm (or per one hundred cubic feet [ccf]) of natural gas by the Btu content per unit of fuel.
• To figure the price you pay per unit, take the total amount of your bills (for oil, electricity, propane, or natural gas) during the heating season, and divide it by the total number of gallons, kWh, or therms you consumed during those months. Use the following values for fuel Btu content:
o #2 Fuel Oil = 140,000 Btu/gallon
• Electricity = 3,413 Btu/kWh
• Propane = 91,600 Btu/gallon
• Natural Gas = 103,000 Btu/ccf
• or 100,000 Btu/therm
• E = Efficiency of the heating system. For gas, propane, and fuel oil systems this is the Annual Fuel Utilization Efficiency or AFUE. Typical AFUE values are 0.6 to 0.88 for oil or propane furnaces, and 0.7 to 0.95 for natural gas furnaces. Older systems are usually less efficient. Use E = 1.00 for baseboard electric systems. For heat pumps, use the Coefficient of Performance or COP for E; where E = 2.1 to 2.5 for conventional heat pumps, and E = 3.2 to 3.5 for geothermal heat pumps.
• R(1) = Initial R-value of section
• R(2) = Final R-value of section
• R(2) - R(1) = R-value of additional insulation being considered
• HDD = Heating degree days/year. This information can usually be obtained from your local weather station, utility, or oil dealer
• 24 = Multiplier used to convert heating degree days to heating hours (24 hours/day)."

ENERGY STAR is a joint program of the U.S. Environmental Protection Agency and the U.S. Department of Energy helping consumers save money and protect the environment through recommending energy efficient products and practices. ENERGY STAR estimates that energy efficient choices can save the average homeowner 30% on their energy bill and a similar savings of greenhouse gas emissions, without sacrificing features, style or comfort.

To find out how to improve your specific home`s energy efficiency, you can use either of two online calculators - The Home Energy Yardstick or the Energy Advisor.

Home Energy Yardstick

http://www.energystar.gov/index.cfm?c=home_energy_yardstick.index
ENERGY STAR offers an online calculator to see how your home energy use compares to other US households. You can use the Home Energy Yardstick to find out how much you can save by improving your home`s energy efficiency. Enter the home`s age, square footage, number of occupants and energy bill totals for a consecutive 12-month period.

The Home Energy Saver`s Energy Advisor (also part of the ENERGY STAR program)

http://hes.lbl.gov/
Energy Advisor is a program used to calculate energy use in residential buildings and help consumers identify ways to save energy in their homes based on a detailed description of the home provided by the user. The program performs an annual simulation for the user`s weather location using default energy prices by state. The program provides a report showing a list of recommendations ranked by time to payback based on the specific home being evaluated.

The North American Insulation Manufacturer`s Association presents the study highlights for two studies conduct by the Harvard University School of Public Health on the costs of inadequate home insulation. Environmental insulation costs are measured in human health based on improved indoor air quality with fewer airborne particulates.

"The Existing Homes Study (Pub # RP061) showed that if the 46 million existing single-family homes in the United States that have inadequate insulation were retrofitted with additional insulation to meet the 2000 IECC standards, the annual benefits would include:

• 240 fewer premature deaths, 6,500 fewer asthma attacks,110,000 fewer restricted activity days per year
• This translates into a potential savings of $1.3 billion per year in averted costs such as health care, and $5.9 billion per year in additional savings associated with reduced energy consumption, paying back the initial cost of the insulation in about six years
• Annual energy savings of more than 800 Trillion Btu, which would result in lower emissions
• 3,100 fewer tons of fine particulate matter (PM2.5)
• 100,000 fewer tons of NOX (a particle precursor)
• 190,000 fewer tons of SO2 (a particle precursor)

The New Homes Study (Pub # RP060) looked at increasing insulation in the 1.2 million new homes built in the US each year to the 2000 IECC standards would, over 10 years:

• Save 300 billion BTUs each year - This equals 28 supertankers of crude oil and 300 billion cubic feet of natural gas
• Save 60 lives, 2,000 fewer asthma attacks, and 30,000 fewer restricted activity days
• Lower emissions of:
• 1,000 fewer tons of fine particulate matter (PM2.5)
• 30,000 fewer tons of NOx
• 40,000 fewer tons of SO2"

Smart Homeowner Magazine,
"Exactly How Much Insulation Pays for Itself?",
No. 15 - January/February 2004.

US Department of Energy,
"A Consumers Guide to Energy Efficiency and Renewable Energy, Estimating the Payback Period of Additional Insulation",
2005.

North American Insulation Manufacturers Association (NAIMA),
www.naima.org.

Florida Solar Energy Center,
"Radiant barriers: a question and answer primer",
http://www.fsec.ucf.edu/en/publications/html/FSEC-EN-15/index.htm.

Oxford City Council,
http://www.oxford.gov.uk/environment/insulation.cfm.

Plymouth City Council,
http://www.plymouth.gov.uk/insulation.