Insulation Investment Calculator
Have you ever invested money in the stock market, or
put money into an interest bearing bank account? If so, you
were interested in the rate of return on your investment.
Spending money on insulating your house is also an investment.
It's return is in consistently lower utility bills to heat and cool your
Insulation resists the flow of heat. Knowing the R values
before and after an insulation upgrade and the
average temperature difference across the insulation, you can
calculate the amount that the insulation upgrade reduces
heat flow. Knowing the cost of energy and the cost of the
insulation upgrade, you can calculate the rate of return on your
investment in insulation.
This interactive calculator does these calculations for you,
letting you quickly and easily investigate the cost-effectiveness
of various insulation upgrades.
Don't be surprised at a fairly large rate of return, especially if your house is poorly insulated,
you live in a severe climate, have an inefficient heating or cooling unit, or expensive fuel.
Bear in mind that this calculates monetary rate of return. The savings of energy is also
environmentally beneficial, reducing a variety of pollutants, and conserving finite fossil fuel
- COP stands for "Coefficient of Performance". It is a non
dimensional representation of the efficiency of a cooling or heating
system, as is EER, which has the units of BTUH/Watt. To convert EER to
COP, multiply it by 0.293.
- Heating Degree Days and Cooling Degree Days, or HDD/CDD. These are
tracked by the Weather Service, and represent the number of days that the
outside temperature is cooler or warmer than some assumed inside temperature,
multiplied by the temperature difference. It is common for HDD and CDD to
both be calculated against an inside temperature of 65F, which is
a little colder than most indoor spaces in winter, and much cooler in the
summer. It is appropriate when using this calculator to increase the
HDD a little, and decrease the CDD by quite a lot, depending on local
This Calculator Supplied courtesy of
Chuck Wright Consulting, Technology Serving Sustainability