ECBC LPD vs ASHRAE 90.1 vs EN 15193 — 10.4 kW Spread Per Office Floor
By MEPVAULT Editorial Team · MEP Consultant · Electrical / Sustainability · 11 May 2026
Reading time ~ 8 min · Originally published: 10 May 2026 · Last revised: 11 May 2026
On a 4,000 m² IT-park office floor in Hyderabad, ECBC 2017 allows 41 kW of connected lighting load. ASHRAE 90.1-2022 caps it at 30.6 kW. The 10.4 kW delta translates to ~₹2.9 lakh/year in lighting + cooling energy plus one LEED EA credit point. Two codes, two numbers, one design decision.
What LPD really means and why three codes disagree
Lighting Power Density (LPD) is watts of connected lighting load per square metre of conditioned floor area. ECBC 2017 caps it on a building-by-space basis; ASHRAE 90.1 publishes the same table with somewhat lower allowances; EN 15193 reframes the question entirely as Lighting Energy Numeric Indicator (LENI, kWh/m²/year) which incorporates daylight, occupancy, and operating-hours assumptions before computing the limit.
For an Indian project the difference between ECBC and ASHRAE 90.1 is the difference between meeting code minimum and qualifying for ECBC+ / Super-ECBC / LEED EA credit ladder.
Worked example — 4,000 m² IT-park office floor in Hyderabad
| Space | Area (m²) | ECBC 2017 LPD | ASHRAE 90.1 LPD | ECBC kW | ASHRAE kW | Δ kW |
|---|---|---|---|---|---|---|
| Open-plan workstations | 2,800 | 10.5 | 7.3 | 29.4 | 20.4 | 9.0 |
| Conference rooms (4 nos) | 200 | 12.5 | 11.2 | 2.5 | 2.2 | 0.3 |
| Cabin offices (12 nos) | 480 | 11.0 | 9.7 | 5.3 | 4.7 | 0.6 |
| Corridors + circulation | 320 | 6.0 | 6.0 | 1.9 | 1.9 | 0.0 |
| Pantry + breakout | 200 | 9.5 | 7.0 | 1.9 | 1.4 | 0.5 |
| Total connected lighting | 4,000 | — | — | 41.0 | 30.6 | 10.4 |
The 10.4 kW gap between an ECBC-only and an ASHRAE-90.1-compliant design on this floor translates to:
- ~26,000 kWh/year direct lighting energy
- ~7,800 kWh/year additional cooling avoided (heat-of-lights load reduction)
- ~33,800 kWh/year total — ~₹2.9 lakh/year at ₹8.5/kWh
- One LEED EA credit point (Option 2 building-area LPD reduction ≥ 25 %)
How to design to the lower bound without making the space cave-dark
The trade we make on every IT-park office: drop LPD from ECBC’s 10.5 W/m² to ASHRAE’s 7.3 W/m² by combining task-ambient lighting (300 lux at workplane via desk-mount task lights, 100–150 lux ambient via ceiling) instead of uniform 500 lux ceiling. ECBC 2024 explicitly recognises this approach in chapter 6 §6.3.2 — task-ambient gets a 0.85 multiplier on the space LPD.
Three things have to be in the design basis for this to actually work at site: (i) task light specification on the BoQ, not “by tenant”, (ii) occupancy sensors with daylight harvesting on ceiling-row 1 (perimeter), and (iii) a commissioning protocol that verifies installed lux at 1 m grid before handover. We have seen projects where the design hit 7.3 W/m² on paper and the as-built measurement came back 9.8 W/m² because the contractor swapped the specified 2×2 ft LED panel for a cheaper one with higher input wattage. Audit the BoQ before approval.
Lighting on the EA credit ladder
| Rating | Pathway | LPD reduction target |
|---|---|---|
| IGBC v3 NB | EE-1 Optimise Energy Performance | ≥ 12 % below ECBC baseline = 1 point |
| IGBC v3 NB | EE-1 (max) | ≥ 30 % below ECBC = 6 points |
| LEED v4.1 BD+C | EA Optimise Energy Performance Opt 2 | ≥ 25 % LPD reduction = 4 points |
| ECBC+ | ECBC chapter 6 §6.5 | 15 % below ECBC LPD |
| Super-ECBC | ECBC chapter 6 §6.5 | 30 % below ECBC LPD |
For most office projects we target the IGBC v3 6-point + LEED v4.1 4-point ladder simultaneously — the 30 % reduction satisfies both. The trade-off is task-light specification rigour at site, not capex.
References
- Energy Conservation Building Code 2017 — Bureau of Energy Efficiency, MoP GoI, Chapter 6 (Lighting).
- Energy Conservation and Sustainable Building Code 2024 — BEE, Chapter 6 (Lighting and Controls) §6.3.2.
- ASHRAE Standard 90.1-2022 — Energy Standard for Sites and Buildings, Table 9.5.1 (Space-by-Space LPD), ASHRAE Atlanta.
- EN 15193-1:2017 — Energy performance of buildings — Energy requirements for lighting — Specifications, CEN Brussels.
- IS 3646 (Part 1): 1992 — Code of Practice for Interior Illumination, Bureau of Indian Standards.
- IES Lighting Handbook (11th edition) — Illuminating Engineering Society, New York.
- IGBC Green New Buildings Rating System v3.0 — IGBC 2023, EE-1 Optimise Energy Performance credit.
- LEED v4.1 BD+C Reference Guide — USGBC 2024, EA Optimise Energy Performance Option 2.
// About the Author
MEPVAULT Editorial Team — A team of practising MEP consultants based in India. ISHRAE Mumbai chapter member; FSAI affiliate.