Energy Efficiency ROI Calculator

First work out the annual energy saving: the difference in kWh between the old and new equipment, multiplied by your cost per kWh. The payback period is then simply the upfront investment divided by that annual saving. A four-month payback, for example, means the upgrade pays for itself in a third of a year and everything after that is profit.

Multiply the power rating in watts by the hours of daily use, divide by 1,000 to convert to kWh, and multiply by the number of operating days a year. Doing this for both the existing and the replacement equipment gives the annual consumption of each, and the gap between them is your saving in kWh.

LED relamping often shows a very fast payback (a few months to a year) and a 5-year ROI well into the hundreds of percent, because lighting runs for long hours and the wattage cut is large. Refrigeration and cooking equipment tend to have longer paybacks because the upfront cost is higher, but they can still be strongly positive over five years. The calculator gives you the payback and the 5-year ROI so you can rank competing projects.

It takes the annual saving multiplied by five years, subtracts the original investment, and divides the result by that investment, expressed as a percentage. So an investment that returns more than its cost across five years shows a positive ROI; one that pays back in under a year typically shows several hundred percent over the full period. It is a simple model that ignores energy-price inflation and maintenance, which usually makes it conservative.

The CO2 avoided is an estimate: it depends on the carbon intensity of your electricity, which varies by country, supplier and even time of day. Treat the kg CO2e avoided as indicative. The kWh and euro savings are more robust because they come directly from your own consumption and tariff.