— Energy Readiness · Commercial / office
40,000 sq ft office: ~59,000 kWh/yr addressable
Problem. A facilities lead planning an LED-and-controls retrofit on a 40,000 sq ft, 12-hour corporate office needs a defensible first-pass on how much annual electricity a coordinated upgrade could realistically address. The question is not a slogan but a number: how many kWh a year are actually in play before anyone commissions a detailed audit.
Answer. At an office energy-performance index of 85 kWh/m²/yr across ~3,716 m², this configuration models a baseline of roughly 316,000 kWh/yr, of which about 18.6 percent — close to 59,000 kWh/yr — is addressable through HVAC, lighting and scheduling measures. That saving band carries roughly 42 tonnes of CO₂ a year at the CEA grid factor of 0.71 kg/kWh.
02 / In depth
How this preset reads — the engineering view.
The model applies a BEE-style energy-performance index (EPI) to floor area and an operating-hours factor. For a 12-hour office the midpoint EPI is 85 kWh/m²/yr, split at roughly 55 percent HVAC and 18 percent lighting. The addressable band is built from three ASHRAE 90.1 / BEE midpoints — 16 percent of the HVAC load, 35 percent of the lighting load, and 3.5 percent of the total for power-factor and scheduling — which together resolve to about 18.6 percent for this use-mix.
Here the 40,000 sq ft input converts to ~3,716 m² (÷ 10.7639). Multiplying 85 × 3,716 gives a baseline near 316,000 kWh/yr; 18.6 percent of that is close to 59,000 kWh/yr addressable, carrying roughly 42 tonnes of CO₂ a year. The headline figure is the absolute kWh — that is the number that scales with floor area and hours — while the 18.6 percent is a property of the office use-mix alone.
Increasing floor area or operating hours raises the absolute kWh in play monotonically, because both enlarge the baseline the percentages act on. The percentage itself barely moves with size — it shifts only when the use-type changes the HVAC-versus-lighting split — so a larger office shows a much larger kWh headline at a near-identical percentage. Read the two figures separately: area drives the kWh, use-mix drives the percentage.
The tool is a screening estimate, not a measured saving. It does not model the actual installed plant, control strategy, envelope condition, tariff structure or occupancy schedule, and it does not stand in for a metered energy audit. Treat the output as a shortlisting figure that tells you whether a detailed HVAC and lighting study is worth commissioning — not as a commitment to a specific outcome.
What this preset deliberately does not solve
- Screening estimate from EPI midpoints — not a metered saving or an audit result.
- Ignores installed plant, controls, envelope, tariff and real occupancy patterns.
- The percentage reflects the office use-mix only; the kWh headline scales with area and hours.
How this preset differs from its siblings
The sibling hospital preset models a far higher EPI (340 vs 85 kWh/m²/yr) over a larger, 24×7 footprint, so it shows a much larger absolute kWh saving at a slightly lower percentage. Use this office preset for a daytime commercial building where lighting and HVAC dominate and a retrofit is the main lever; use the hospital preset where round-the-clock operation and clinical loads set the baseline.
03 / Hydrated calculator
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