SIR: Savings to Investment Ratio
A ratio used to determine whether a project that aims to save money in the future is worth doing. The ratio compares the investment that is put in now with the amount of savings from the project. SIR takes the total energy savings over the lifetime of the improvement (Present Value) divided by the upfront cost of the investment.
The net SIR — the one shown in the Metrics view as well as at the top of the Refine screen — multiplies each recommendation's lifetime (see below) times the present value of savings for each item and then adds them up. This total lifetime savings is then divided by the grand total cost for the project.
Lifetime Improvement Chart
This set of lifetime measures is used for all jobs in Snugg Pro EXCEPT the State of New York, which has it's own set of lifetimes.
Attic: 20
Ceiling: 20
AirSealOnly: 15
Walls: 20
Door: 20
Windows: 20
Floor: 20
BsmtSlab: 20
Crawl: 20
Thermostat: 15
SealDucts: 15
Heating: 15
Cooling: 15
CFL: 7
Refrigerator: 15
Freezer: 15
DHW: 13
Dishwasher: 15
ClothesWasher: 15
We set the lifetime for heating systems in general to 20 years, but we currently have no way to set it to 25 years if it’s a boiler.