How the Keep-or-Replace Comparison Works
Net ownership difference = annual energy-cost savings ? ownership years ? relevant net upfront cost
For a working appliance, relevant net upfront cost is purchase price plus installation and other cost minus rebate. For a necessary replacement, only the efficient option incremental premium over the standard option is compared with energy savings.
Simple payback divides relevant net upfront cost by positive annual savings. Verdict rules first check comparable service and input basis, then savings, closeness, and whether payback fits within the ownership period. Results are scenarios, not financial or professional advice.
Frequently Asked Questions
Can the calculator recommend keeping my appliance?
Yes. When a working appliance has no positive savings or modeled payback falls outside the ownership period, Keep can be the energy-cost result.
Why compare only the efficiency premium when replacement is necessary?
If replacement is already necessary, the standard option cost is unavoidable in both choices. The decision compares the efficient option incremental premium with its energy-cost savings.
Does lower wattage always mean better efficiency?
No. Options must provide comparable capacity and service, and energy use over a comparable task or year is more useful than raw watts alone.