Example Data Table
| Device Type |
Input Power |
Useful Output Power |
Efficiency |
Possible Grade |
| Efficient electric motor |
1500 W |
1350 W |
90.00% |
A+ |
| LED lighting system |
120 W |
102 W |
85.00% |
A |
| Older pump system |
2200 W |
1320 W |
60.00% |
C |
| Heat pump output comparison |
900 W |
3000 W |
333.33% |
A+++ |
Formula Used
Energy efficiency:
Efficiency (%) = Useful Output Energy / Input Energy × 100
Power based efficiency:
Efficiency (%) = Useful Output Power / Input Power × 100
Energy loss:
Energy Loss = Input Energy - Useful Output Energy
Annual energy use:
Annual Energy = Input Power / 1000 × Runtime × Days × Load Factor + Standby Energy
Annual cost:
Annual Cost = Annual Energy Use × Electricity Price
Emission estimate:
Annual Emissions = Annual Energy Use × Carbon Factor
Some thermal systems can show values above 100 percent.
Heat pumps may deliver environmental heat plus purchased energy.
Compare ratings within the same equipment type.
How to Use This Calculator
- Enter the device or system name.
- Add input energy and useful output energy for an energy based test.
- Add input power and useful output power for a power based test.
- Enter runtime, operating days, standby power, and load factor.
- Add electricity price and carbon factor for cost and emission estimates.
- Enter baseline power to estimate possible savings.
- Press the calculate button to view the rating above the form.
- Use CSV or PDF buttons to save the result.
Energy Efficiency Rating Guide
What the Rating Means
Energy efficiency rating shows how well a device converts supplied energy into useful output.
A motor may turn electric power into shaft power.
A lamp may turn electric power into useful light.
A heating or cooling unit may move thermal energy.
The rating helps compare performance, waste, and running cost.
Higher efficiency usually means less wasted energy.
It also means lower operating cost during regular use.
Why Physics Inputs Matter
Good rating work starts with clear measurements.
Input energy must match the same test period as useful output energy.
Input power should match the same load condition as output power.
Runtime, days, and load factor then convert the test into yearly use.
This makes the result more practical.
It connects laboratory style data with real operating behavior.
Reading Losses and Grades
The calculator reports efficiency, loss percentage, annual energy use, and a grade.
The grade is a simple guide.
It should not replace official labels.
It is useful for screening designs, comparing equipment, or checking project assumptions.
A low grade means the device wastes a larger share of input energy.
A better grade means more useful work is produced from the same supply.
Cost and Environmental View
Energy efficiency is not only a physics number.
It affects bills and emissions.
Annual cost is based on yearly energy use and electricity price.
Emissions are based on the selected carbon factor.
Baseline power helps estimate savings against an older device.
Payback compares upgrade cost with yearly cost savings.
This gives a clear financial view.
Using Results Wisely
Use measured data whenever possible.
Check nameplate values if direct measurements are not available.
Avoid mixing peak power with average output.
Include standby power for equipment that remains connected.
Review uncertainty when readings come from meters or estimates.
Small errors can change the final grade.
For heat pumps and recovery systems, efficiency can exceed 100 percent.
In those cases, compare similar systems only.
FAQs
1. What is energy efficiency rating?
It is the percentage of input energy converted into useful output. A higher value means the device wastes less energy during operation.
2. Can efficiency be above 100 percent?
For ordinary conversion devices, it should not exceed 100 percent. Heat pumps can appear higher because they move environmental heat, not only purchased energy.
3. Should I use energy or power inputs?
Use energy values when you know total kWh for a test. Use power values when you know input watts and useful output watts.
4. What is load factor?
Load factor is the average operating load as a percentage of full load. It improves yearly energy estimates for variable operation.
5. Why include standby power?
Many devices consume energy while idle. Standby power can become significant when equipment remains connected for many hours daily.
6. How is annual cost calculated?
The calculator multiplies estimated yearly energy use by the electricity price per kWh. Change the price to match your local rate.
7. What does the baseline power field do?
Baseline power represents an older or alternative device. The calculator compares it with your current system to estimate yearly savings.
8. Is this an official appliance label?
No. It is an engineering calculator for estimates and comparisons. Official labels depend on certified tests and regional standards.