Build the numerator and denominator carefully
Whole-building site EUI combines the energy consumed at the property from relevant fuels and divides it by gross floor area. Electricity and gas must be converted into compatible units. Include the complete building boundary rather than omit tenant meters or an untracked fuel. Verify the period and floor-area definition. A property that excludes a major process or leased area can appear artificially efficient. Keep the raw utility data and boundary notes so the calculation is reproducible.
Site and source energy are different measures
Site energy reflects consumption at the building, while source energy accounts for upstream energy associated with producing and delivering it. ENERGY STAR explains why source energy supports certain national comparisons and scoring. Changing fuels can affect site and source metrics differently. Do not compare one property’s source EUI with another’s site EUI, or interpret a lower site number as a complete emissions assessment. Record the methodology and factors used, especially across portfolio reports or successive reporting years.
Use appropriate peers and operating context
Hospitals, restaurants, warehouses, and offices have different service demands. Hours, climate, occupancy, production, and equipment can materially affect energy intensity. Published medians provide context rather than a guaranteed achievable target. ENERGY STAR scores are available for qualifying property types under their program methods; not every building receives one. A benchmark gap should lead to an investigation with site staff and measurements, not a fabricated savings estimate. Preserve raw and normalized values where normalization is used.
Hypothetical EUI calculation
A 20,000-square-foot building uses an illustrative 1,000,000 kBtu of total annual site energy. Site EUI is 50 kBtu/ft²-year. If 200,000 kBtu of a separate meter was omitted, the corrected result becomes 60. A peer benchmark comparison would change materially before any equipment was repaired. This example shows why complete boundaries matter. It is not a national median or a claim that 50 is an appropriate target for every type of business.
Practical review checklist
- Define building boundary, gross floor area, full-year period, and all included meters and fuels.
- Convert energy units consistently and label site, source, and electricity-only metrics accurately.
- Compare suitable property types and operating conditions, retaining raw and normalized values.
- Investigate gaps with measurements before assigning savings, project costs, or performance claims.
Questions & answers
Is a low EUI always proof of good performance?
Not alone. Incomplete meters, unusual occupancy, different uses, or boundary errors can also produce a low value.
Can all properties receive an ENERGY STAR score?
No. Scoring eligibility and methods depend on the property type and program requirements. EUI can still provide useful context.
Sources & scope
Primary references reviewed October 15, 2026. These sources support the stated concepts; actual tariffs, program rules and signed agreements govern the account. Decision examples and operational worksheets are original educational analysis.
- ENERGY STAR: What is energy use intensity?
Annual energy per area and property-type comparison. - ENERGY STAR: Source and site energy
Difference between utility-meter energy and source-energy accounting. - ENERGY STAR: Analyze benchmarking results
Peer comparisons, performance tracking, and score interpretation.