What the Insignia NS-BI1ZWCxxxxxx (x = a-z, A-Z, 0-9, -, blank) costs to run
ENERGY STAR certifies the Insignia NS-BI1ZWCxxxxxx (x = a-z, A-Z, 0-9, -, blank) at 155 kWh/yr, one of the cheaper models in its category to run for its category.
That $29 is priced at 18.8¢/kWh, the average of all 51 state rates this site tracks. Your own state's rate is one click away.
Efficient, or not, for a refrigerator
Against the category average of 386 kWh/yr, this model uses 59.8% less, ranking 123 of 4,704 refrigerators tracked here for running cost. That average is drawn from all 4,704 refrigerators ENERGY STAR currently certifies, not an outside number, a $43/year gap from this model at the national rate. Full sourcing is in the sourcing notes.
Right next to it on the list
A rank or two either side of the Insignia NS-BI1ZWCxxxxxx (x = a-z, A-Z, 0-9, -, blank): Zephyr PRW24C02AG-ADA ($29/yr, 153 kWh/yr), then Liebherr HW 8000 ($29/yr, 155 kWh/yr).
Same brand, different models
Ranked 5 of Insignia's 92 certified refrigerators, this sits between the NS-WC14SS3 ($23/yr, the brand's cheapest) and the NS-RBM18WH0-C ($88/yr, its priciest).
What this adds up to over time
NAHB's Study of Life Expectancy of Home Components puts a typical refrigerator's service life at 13 years; run the Insignia NS-BI1ZWCxxxxxx (x = a-z, A-Z, 0-9, -, blank) that long and it costs about $379 in electricity, on top of whatever it cost to buy.
Is it worth replacing?
Efficient as certified refrigerators go, $29/year is a reasonable baseline if you're comparing what else is on the market.
Compare current ENERGY STAR certified refrigerators before buying.
If you're keeping it
At $29/year just to run, a refrigerator is worth protecting against an unplanned repair bill on top of that.
Where this number comes from
Nothing here is estimated from a nameplate wattage; the 155 kWh/yr is ENERGY STAR's own certified figure for this model. Ranked 123 of 4,704, the Insignia NS-BI1ZWCxxxxxx (x = a-z, A-Z, 0-9, -, blank) sits in the middle of the refrigerator category, see the guide to why your state changes this number for the other half of the math.