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Sustainability # 3 Examples of the Energy Efficiency Formula

, updated on June 30, 2017 The energy efficiency formula is a method of calculating the efficiency of energy production and consumption. It can be used to measure the efficiency of infrastructure, facilities, buildings, transport, products and services.

## Energy Efficiency Formula

The energy efficiency formula is based on energy output and input.
energy efficiency = (energy output / energy input) × 100
Energy output is the useful energy offered by an item such as the light generated by a light bulb.

## Example 1

A solar module produces up to 320 watts of power from 1500 watts of sunlight.
energy efficiency = (320/1500) × 100 = 21.3%

## Example 2

An electric car consumes 20 kWh of power on a drive and transfers 10.5 kWh of power to the wheels.
energy efficiency = (10.5/20) × 100 = 52.5%

## Example 3

A gasoline burning car consumes fuel with an equivalent of 60 kWh of energy on a drive and transfers 11 kWh of power to the wheels.
energy efficiency = (11/60) × 100 = 18.3%

## Similar Measurements

The energy efficiency formula is a technical measurement that isn't always useful in comparing real world efficiencies. A large number of alternative measurements are commonly used. For example, energy per passenger mile is a common way to calculate efficiency for transportation.
 Overview: Energy Efficiency Formula Type Definition A method of calculating the efficiency of energy production and consumption. Related Concepts

## Energy Efficiency

This is the complete list of articles we have written about energy efficiency.
Daylighting
Efficiency Formula
Embodied Energy