The Sun & Earth Cumulative Savings Calculator is an Excel spreadsheet that calculates the difference in home ownership costs for an energy efficient building compared to a conventional building.
Click on “Inputs and 30 Year Annual” to change the parameters for the spread sheet. For instance, change Income Tax Rate from 25% to 15% or interest rate from 6% to 3%.
Click on “20 Year Cumulative” to show the cost differences at the end of a 20 year mortgage between conventional and energy efficient buildings. In this example the cost savings of an energy efficient building is almost $114,000.
Several deductions can be made from these calculations:
-A relatively modest initial expenditure in energy efficiency makes a large difference in ownership costs.
-This expenditure on energy efficiency makes a large difference in the resale value of the building in comparison to the costs of energy in a conventional building which is just money lost.
-While an investment in many components of a building will depreciate or just increase at the rate of building costs, an investment in energy efficiency will appreciate at the rate of building costs plus the increase in costs of energy.