The Energy Use Index Calculator measures the energy performance of a building by calculating the amount of energy consumed per unit area annually. This metric, known as the Energy Use Index (EUI), is widely used in green building certification, energy audits, facility management, and sustainable design. It provides a clear comparison of energy usage across buildings of different sizes. This tool belongs to the Building Energy Performance Calculator category.
The EUI enables building owners, energy managers, architects, and policymakers to assess energy efficiency, benchmark facility performance, and prioritize upgrades for energy savings.
Formula of Energy Use Index Calculator
EUI = Annual Energy Consumption / Gross Floor Area
Detailed Breakdown:
- EUI (Energy Use Index)
The result is typically expressed as kilowatt-hours per square meter per year (kWh/m²/year) in metric units or British Thermal Units per square foot per year (BTU/ft²/year) in imperial units. - Annual Energy Consumption
This is the total amount of energy the building consumes over a year, including electricity, heating, cooling, and fuel (in kWh, BTU, or equivalent units). - Gross Floor Area
The total enclosed area of the building, measured in square meters (m²) or square feet (ft²), including all occupied and utility spaces.
Units:
- Metric: kWh/m²/year
- Imperial: BTU/ft²/year
It’s important that the energy consumption and floor area are in compatible units to maintain accuracy.
Quick Reference Table
This table shows typical EUI ranges for different building types, helping users compare and evaluate energy performance without calculating each time:
| Building Type | Typical EUI (kWh/m²/year) | Typical EUI (BTU/ft²/year) |
|---|---|---|
| Office Building | 150 – 250 | 47,500 – 79,000 |
| School | 100 – 200 | 31,500 – 63,000 |
| Hospital | 250 – 500 | 79,000 – 158,000 |
| Retail Store | 120 – 250 | 38,000 – 79,000 |
| Residential (Apartment) | 80 – 150 | 25,200 – 47,500 |
These figures are industry benchmarks that help identify whether a facility is underperforming or operating efficiently.
Example of Energy Use Index Calculator
Let’s say a commercial building consumes 360,000 kilowatt-hours of energy in one year and has a total floor area of 2,000 square meters.
Step 1:
Use the formula:
EUI = Annual Energy Consumption / Gross Floor Area
EUI = 360,000 / 2,000 = 180 kWh/m²/year
This building has an EUI of 180 kWh/m²/year, which is within the average range for commercial buildings, indicating moderate energy efficiency.
Most Common FAQs
A good EUI depends on the building type and its use. Lower values indicate higher efficiency. Office buildings below 150 kWh/m²/year or 47,500 BTU/ft²/year are generally considered efficient.
Yes. The calculator works for all building types, as long as you have the total annual energy use and the gross floor area.
Yes. It typically includes electricity, gas, heating oil, and any other energy sources consumed by the building.