1. What is Energy Usage Index (EUI)?

The Energy Usage Index (EUI) measures a building's energy efficiency by calculating energy consumption per unit area per year. It's expressed in kWh/m²/year and is a key metric for comparing energy performance across different buildings.

2. How Does the Calculator Work?

The calculator uses the EUI formula:

Where:

• Annual Energy — Total energy consumption in kilowatt-hours (kWh)
• Floor Area — Total floor area in square meters (m²)

Explanation: The equation divides the total annual energy consumption by the building's floor area to determine energy efficiency per square meter.

3. Importance of EUI Calculation

Details: EUI is crucial for benchmarking building energy performance, identifying energy efficiency opportunities, and meeting sustainability goals. Lower EUI values indicate better energy efficiency.

4. Using the Calculator

Tips: Enter annual energy consumption in kWh and floor area in m². Both values must be positive numbers for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a good EUI value?
A: EUI values vary by building type, but generally, lower values indicate better efficiency. Typical office buildings range from 150-300 kWh/m²/year.

Q2: How can I improve my building's EUI?
A: Energy efficiency measures like LED lighting, improved insulation, efficient HVAC systems, and renewable energy installations can reduce EUI.

Q3: Does EUI account for different energy sources?
A: EUI typically measures delivered energy (site energy) but can also be calculated for source energy which accounts for generation and transmission losses.

Q4: How does building occupancy affect EUI?
A: While EUI normalizes for size, high-occupancy buildings may have higher EUI values due to increased energy use for lighting, equipment, and ventilation.

Q5: Is EUI used in UK building regulations?
A: Yes, EUI is increasingly used in UK building standards and energy performance certificates to quantify and compare building energy efficiency.