Energy ROI Calculator.
Indicative payback for a BMS-driven energy upgrade plus daylight-harvesting LED retrofit. Conservative model; defensible numbers; designed for the first board conversation.
- Typical payback
- 4–5 yrs
- Annual saving
- 22–28%
- Effectiveness
- 92%
- Model basis
- Measured
— ROI · BMS & lighting retrofit
The math, in plain numbers.
Adjust the building's variables and see an indicative payback period for a BMS-driven energy upgrade plus daylight-harvesting LED retrofit. Deliberately conservative; defensible in a first conversation.
Annual energy bill (today)
₹ 5.22 Cr
55,00,000 kWh / year
Indicative annual saving
₹ 1.21 Cr
12,70,500 kWh saved per year
Indicative project cost
₹ 75.0 L
BMS + lighting retrofit + commissioning
Simple payback
0.6 years
Excluding tariff escalation
Saving breakdown
- BMS-driven HVAC optimisation (~20%)48%
- Lighting retrofit + daylight harvesting (~38%)33%
- Tariff & power-factor optimisation (~4.5%)19%
Beyond the bill
902tonnes of CO₂ avoided per year
Indian grid factor · 0.71 kg CO₂ per kWh
These are indicative figures — site audit, occupancy patterns, building envelope, weather profile and existing system condition all affect the real number. We model the actual case during the brief stage and provide a written ROI report you can take to the board.
Opens a print-styled brief — save as PDF via your browser
· Example use
A 60,000 sq ft commercial office paying around ₹9 per unit, running fluorescent lighting and standalone HVAC controls, lands on a four to five year payback when retrofitted with a BMS-driven control layer plus daylight-harvesting LED. Annual savings around 22 to 28 percent of the electricity bill, declining slightly across the decade as devices age. The model assumes nothing about behavioural change — savings come from controls, not from staff.
· Frequently asked
The energy case —
what people ask first.
What is included in the BMS scope?
Sensor-driven HVAC scheduling, occupancy-based lighting, daylight harvesting in perimeter zones, plug-load control on shared circuits and a head-end dashboard with monthly reporting. Tenant fit-out lighting is excluded unless commissioned together.
Why daylight harvesting specifically?
Because perimeter zones in Indian commercial buildings receive enough daylight that overhead lighting can dim by 30 to 60 percent during working hours without an occupant noticing. The retrofit cost is small; the saving compounds for the lifetime of the fixture.
How conservative are the numbers?
We use measured baseline tariffs, ten percent annual capacity fade on lighting, no behavioural-savings assumption, and a flat 92 percent BMS effectiveness factor. Real savings tend to come in 5 to 10 percent above the model; we publish the floor.
Will the retrofit qualify for any incentive?
BEE, EESL and several state DISCOMs run rebate or financing programmes for energy-efficiency retrofits; some MNCs run internal capex programmes for sustainability-aligned projects. We do not include incentives in the base case — they sweeten the result, they do not justify it.
Is this for new buildings or retrofits?
Primarily retrofits — the payback case is sharpest where you can compare a real "before" bill. For new buildings, we run a different model that compares the BMS-driven design against a code-minimum baseline and shows the lifecycle cost difference.
· Begin
Building an energy case
for the board?
Send twelve months of bills, the building drawings and the operating profile. We will return a written ROI model within two working days.