Energy Efficiency Ratio Calculator

Calculate the energy efficiency ratio (η) by dividing useful energy output by energy input, expressed as a percentage. Supports multiple energy units for versatile applications.

Energy Input ▼

Energy Output ▼

Add Comparison System (Optional) ▼

Standard
Step Details
Chart

Result

Calculation Details

Efficiency Comparison

Formulas

Energy Efficiency Ratio Calculation

The energy efficiency ratio is calculated as follows:

η = (E_out ÷ E_in) × 100%

Where:

  • η: Efficiency (expressed as a percentage).
  • E_out: Useful energy output (in selected unit, converted to Joules for calculation).
  • E_in: Energy input (in selected unit, converted to Joules for calculation).

Supported Units:

  • J (Joules), kJ (Kilojoules), MJ (Megajoules)
  • Wh (Watt-hours), kWh (Kilowatt-hours)
  • BTU, kBTU (Thousand BTU), MMBTU (Million BTU), thm (Therm)
  • ft-lb (Foot-pounds), kcal (Kilocalories)

Usage Notes:

  • Results are rounded to 3 decimal places for precision.
  • Efficiency typically ranges from 0% to 100%, but values above 100% may occur in systems like heat pumps due to environmental energy contributions.
  • Comparison system allows relative efficiency analysis.

How to Use the Energy Efficiency Ratio Calculator

  1. Enter System Details: Provide the system name and energy input/output values with their units.
  2. Add Comparison System (Optional): Include another system for comparative analysis.
  3. Choose Display Mode: Select standard, step-by-step, or chart view.
  4. Calculate: Click “Calculate” to process the data.
  5. Export Results (Optional): Download results as JSON.
  6. Reset Data: Click “Reset” to clear all fields.

FAQs (Frequently Asked Questions)

What is energy efficiency?

Energy efficiency is the ratio of useful energy output to energy input, expressed as a percentage, indicating how effectively a system converts input energy into useful output.

Why can efficiency exceed 100%?

In systems like heat pumps or LED lights, apparent efficiency may exceed 100% due to additional energy (e.g., heat) absorbed from the environment, not accounted for in the input.

What units are supported?

The calculator supports J, kJ, MJ, Wh, kWh, BTU, kBTU, MMBTU, thm, ft-lb, and kcal, with automatic conversion to Joules for calculations.

How do I interpret the results?

An efficiency of 0% means no useful output, while 100% indicates no energy loss. Values above 100% suggest environmental energy contributions.

Where can I find energy data?

Energy input/output data can be found in system specifications, energy meters, or engineering datasheets.