Test property portfolio comparisons against area, time and asset mix

A fictional portfolio's reported electricity rises 32%, while a year-end-area division appears to fall 34%. A warehouse enters halfway through the second year. Before describing the lower ratio as improved performance, separate the full reported schedule, a time-weighted diagnostic and the continuing properties.

Fix the three property inputs

This original example compares Year 1 with Year 2. Assume complete whole-property electricity for each stated period, an identical floor-area basis, unchanged areas and no overlapping meters. A and B retain the same energy and service coverage, with twelve months of records in both years. The schedule covers electricity only.

Property A is an office

Area: 10,000 m². Year 1: 1,500 MWh. Year 2: 1,600 MWh. Both records cover January–December.

Property B is a warehouse

Area: 20,000 m². Year 1: 1,000 MWh. Year 2: 1,100 MWh. Both records cover January–December.

Property C is an acquired warehouse

Area: 30,000 m². Acquired on 1 July of Year 2, with 600 MWh recorded for July–December only. C is outside the Year 1 portfolio; no earlier electricity is supplied in this example.

This is a deliberately limited management comparison, not a corporate inventory boundary rule. No unobserved electricity is estimated.

Read the three comparisons separately

The reported quantity rises from 2,500 to 3,300 MWh: (3,300 ÷ 2,500 − 1) × 100 = 32%. The population and months covered have changed.

The year end area creates a misleading annual comparison

Year 1 gives 2,500,000 kWh ÷ 30,000 m² = 83.33 kWh/m² for the full year. Dividing Year 2's 3,300,000 kWh by all 60,000 m² gives 55 kWh/m², apparently 34% lower. C contributes six months of electricity but its entire year-end area. That is an unmatched annual comparison.

Area time weighting addresses one mismatch

For this diagnostic only, weight each observed month as 1/12 of a year. The denominator becomes 10,000 × 12/12 + 20,000 × 12/12 + 30,000 × 6/12 = 45,000 m²-year.

The pooled result is 3,300,000 ÷ 45,000 = 73.33 kWh per m²-year, 12% below Year 1's full-year basis. This month-based convention is not exact calendar-day weighting. It neither fills C's missing months nor adjusts for seasonality.

The continuing properties show an increase

For A and B together, electricity rises from 2,500 to 2,700 MWh, or 8%. Their unchanged 30,000 m² gives 83.33 to 90 kWh/m² for complete years, also an 8% increase. C is excluded because this schedule lacks its comparable full-year records.

Percentages use unrounded ratios; displayed ratios are rounded to two decimals where needed.

Explain the changed result without inventing a cause

The pooled diagnostic still falls because it adds C's relatively low observed electricity per unit of area-time to A and B. Electricity increased at both continuing properties. This demonstrates the effect of this fictional mix; it does not establish that warehouses generally outperform offices.

C's sampled months, occupancy and services may differ from the other properties. Occupancy, operating hours, weather and technical-change evidence are not supplied. The A+B increase establishes no efficiency cause either. In a real comparison, investigate changed uses and services, and verify meter coverage and area definitions before interpreting a ratio.

Keep the full reported quantity, the labelled diagnostic and the named A+B subset together. Retain the exclusion reason. An improvement statement needs a supported explanation beyond these calculations. For the separate causal question, see separating energy savings from operating changes. For basic ratio construction, see calculating intensity from matched quantities.

Apply assessment rules separately

The GRESB 2026 reporting guidance ties data availability to the consumption period and requires consistent reporting levels for like-for-like assessment. Data can precede acquisition; a July purchase does not by itself make earlier data unavailable.

The GRESB operational-energy rules match covered area to reported consumption and assess like-for-like eligibility for asset spaces using full-year records, positive and consistent coverage, and standing-investment status. Apply the current method for a submission. This article's pooled diagnostic is neither its intensity nor its like-for-like calculation; A+B alone establishes no scheme eligibility.

For help organising reporting inputs and a bounded comparison narrative, discuss the records available with Nitium Advisory or call +919322161562.

Method sources checked 13 October 2026. All properties and quantities are fictional. No building rating, verified saving, investment recommendation or independent assurance is claimed.