A deep energy retrofit (DER)can easily cost more than $100,000, and reduce energy bills by 70%. Not a great payback, but is simple payback a logical evaluation tool? Is a lower energy bill the only value derived from a DER?
The answer to the second question provides the basis to answer the first. The monetary value is the least important value from a DER. The improvement in comfort and indoor air quality are the most valuable. To no longer have the wind blow through your house, chilling you, drying out your nose, and bringing in dirt,. mold and other pollutants from within the walls, is a huge improvement in livability. Having a quieter home is another livability improvement.
New windows, siding and roof are going to be needed at some point, and they improve livability, along with increasing resale value and curb appeal. The extra cost of doing a DER when windows and siding are being replaced anyway is the cost that should be considered when calculating the economic value of a DER, and then it is worth it from a simple payback calculation.