Building Energy Use Intensity: How to Calculate EUI

This year's electricity bill for the building is higher than last year's. Has the building become less efficient, or did two more floors fill up? Raw kWh and rupiah figures are hard to judge, because a bigger or busier building will naturally use more energy.

Building energy use intensity (EUI) answers that by dividing a year's energy consumption by floor area, giving kWh per square metre per year. In Indonesia it is known as IKE (intensitas konsumsi energi) and is widely used in building energy audits, whose procedure is set out in SNI 6196:2011. This guide covers how to calculate EUI, the data you need, how to compare it fairly, and how to use it to set and track savings targets.

The building energy use intensity formula

EUI = total energy consumption over 12 months (kWh) ÷ floor area (m²)

As an illustration, an office building with 12,000 m² of floor area that uses 2,160,000 kWh in a year has an EUI of 180 kWh/m²/year. This is an example, not a benchmark. Three things commonly throw the result off:

• Mixing monthly and annual units. Some reports use kWh/m²/month. Multiply by 12 before comparing with annual figures.
• Using only the utility bill. If the building has a genset or rooftop solar, it uses more energy than the PLN meter records. Leave that out and the EUI looks better than it is.
• Less than 12 months of data. Consumption shifts with the seasons, public holidays, and occupancy, so three months do not represent a year.

Data you need to calculate EUI

Data	Source	Note
12 months of energy use	PLN bills, genset meter, solar inverter	Billing periods do not always match calendar months
Floor area	As-built drawings, permit documents	Decide whether basement parking and unconditioned areas count
Use per system	Submeters for cooling, lighting, lifts, pumps, tenants	Shows where the EUI comes from
Operating context	Operating hours, occupancy, changes in floor use	Explains why EUI moves

The definition of floor area is the most common source of disagreement. Some studies divide by air-conditioned area only, others by the whole building. Both are valid as long as they are used consistently and stated in every report. To split consumption by system, our guide to electrical submetering covers where meters are needed.

Reading EUI against a fair comparison

EUI only means something when compared. From most to least reliable:

1. The same building, previous year. Same use, climate, and area definition, so changes are easiest to explain.
2. Similar buildings with the same area definition. Offices, hotels, hospitals, and malls behave very differently because of operating hours, kitchens, and round-the-clock loads.
3. Benchmark tables from the literature. Published EUI benchmarks differ between sources and editions, and some use monthly units. If you need a benchmark for an official report, ask an energy auditor which reference applies to your building type.

A low EUI is not automatically efficient either. A half-empty building can show a low EUI, and so can one that sacrifices comfort. Read EUI alongside occupancy, operating hours, and room temperature and CO₂.

Setting energy-saving targets with EUI

1. Set a baseline: a full 12-month EUI before any change, with notes on occupancy and operating hours.
2. Break it down by system. In tropical buildings cooling is usually among the largest shares, so targets per system are more useful than one total. Practical steps are in our article on saving air conditioning energy in office buildings.
3. Translate it into monthly kWh. Continuing the illustration: cutting EUI from 180 to 165 kWh/m²/year (about 8%) in a 12,000 m² building means saving 180,000 kWh a year, or 15,000 kWh a month on average.
4. Track a rolling 12-month EUI. Each month, add up the last 12 months of consumption and divide by floor area. This smooths out seasonal effects so the direction of change shows sooner.
5. Prove each measure by comparing use before and after on days with a similar pattern.

EUI, energy audits, and mandatory energy management

Government Regulation No. 33 of 2023 on Energy Conservation requires energy users in the building sector consuming 500 tonnes of oil equivalent (TOE) or more per year to run energy management: appoint a certified energy manager, prepare an energy conservation programme, have an energy audit carried out by a certified auditor, and report on implementation. The green building performance assessment under Minister of Public Works and Housing Regulation No. 21 of 2021 also includes energy efficiency as one of its parameters. Check which provisions apply to your building.

In programmes like these, EUI is a simple way to show a building's energy performance year on year. Within an ISO 50001 framework, it can serve as one of the energy performance indicators (EnPIs), as covered in our article on ISO 50001.

Things to keep in mind

• Monthly bills are too coarse to find causes. EUI tells you whether the building is getting less efficient, not where. That needs hourly data per system.
• Changing the area definition or floor use breaks year-on-year comparison. Record every change.
• Savings must not cost comfort or air quality. Watch temperature and CO₂ when air conditioning schedules or setpoints change.

Frequently asked questions

Does basement parking count in the floor area?

It depends on the definition you choose. Parking areas use energy differently from occupied space, so some building managers separate them. What matters is that the definition is consistent and stated in every report.

What is a good EUI for an office building?

There is no single figure that fits every building, and benchmark tables differ between sources. The most reliable comparison is your own building's trend and similar buildings using the same area definition.

Can EUI be calculated per floor or per tenant?

Yes, if each floor or tenant has a submeter. EUI per floor helps find the least efficient areas and makes targets fairer.

Monitoring building EUI with INCLUDE

InEnergy records voltage, current, power, and energy per meter in real time, with a load profile and cost per device based on the tariff you set. That kWh data is the numerator of the EUI. InBuilding (Pro plan and above) adds context per room and zone: occupancy, temperature, CO₂, energy sub-metering, and detection of air conditioning running in empty rooms with an estimate of the kWh wasted. That way EUI stops being a single annual number and can be traced to the zones and hours behind it.

To be clear: data history on the platform follows your plan's retention period, from 30 to 90 days on the Starter to Business plans. For an annual or rolling 12-month EUI, export monthly summaries regularly (Starter plan and above) or use scheduled reports (Business plan).