Turn lighting data into clear annual savings reports. Model dimming, sensors, schedules, and standby loads. See payback, NPV, and emissions reduced across years easily.
| Scenario | Qty | Baseline W | Smart W | Hours/Day | Days/Year | Rate | Occ Save | Day Save |
|---|---|---|---|---|---|---|---|---|
| Retail aisle lighting | 80 | 20 | 12 | 10 | 300 | 0.18 | 0.20 | 0.10 |
| Office open plan | 120 | 36 | 22 | 9 | 260 | 0.16 | 0.25 | 0.15 |
| Warehouse | 60 | 150 | 95 | 12 | 310 | 0.14 | 0.30 | 0.05 |
Use fixture count, wattage, and operating hours to estimate baseline demand. Controls reduce runtime through occupancy and daylight fractions, while dimming factor reduces average draw. Standby watts add a 24‑hour load. For example, 80 fixtures at 20 W running 10 hours for 300 days equals 4,800 kWh annually. Separate zones, and use weighted average hours for the portfolio to avoid double counting.
Energy savings equal baseline kWh minus smart kWh. Cost savings multiply saved kWh by the electricity rate. At 0.18 per kWh, saving 1,000 kWh yields 180 each year. Maintenance savings come from fewer expected replacements when life-hours increase, especially in high-usage zones. If demand charges exist, estimate kW reduction separately and add that annual benefit to the model.
Net investment equals equipment plus installation costs minus total rebates. Per-unit pricing supports mixed portfolios by adjusting the average unit cost. If unit plus install is 35 and quantity is 80, gross investment is 2,800. A 250 rebate lowers net investment to 2,550. Include commissioning, networking, and verification labor within installation when controls require programming.
Simple payback divides net investment by annual savings. Multi-year cashflows escalate savings using the price escalation rate, then discount each year using the discount rate. NPV sums discounted cashflows and investment. IRR is the discount rate that drives NPV to zero, supporting apples-to-apples comparisons. Run sensitivity cases by varying discount rate, escalation, and savings assumptions to reflect uncertainty. across multiple decision scenarios.
Emissions reduction equals saved kWh times the emissions factor. A factor of 0.42 kg per kWh means 1,000 kWh saved avoids about 420 kg CO₂ annually. Pair this output with payback and NPV to build investment cases for sustainability reporting and internal capital reviews. Cite the emissions factor source, note exclusions, and convert kilograms to metric tons for reporting. for summaries.
Quantity, baseline wattage, hours, and electricity rate dominate energy savings. Controls matter next: occupancy, daylighting, and dimming factor. Standby watts can reduce savings in always‑on environments.
Networked drivers, sensors, or gateways can draw power 24 hours. Multiply standby watts by fixtures and days to see its yearly kWh impact. Lower standby improves savings, especially when runtime is short.
The model uses expected replacements per year: operating hours divided by life-hours. It multiplies replacements by your replacement cost. Longer-life smart fixtures reduce replacements and annual maintenance spend.
Payback shows how fast savings recover the upfront investment. NPV discounts future savings to today’s value using the discount rate. A positive NPV indicates the project clears the chosen hurdle rate.
IRR may be unavailable if cashflows never cross zero within the search range, such as when savings are too small or investment is zero. Improve inputs or extend years to create a solvable profile.
Yes. Use weighted averages for wattage, hours, and costs, or run separate scenarios for each area and sum results externally. Keep assumptions consistent across scenarios for fair comparisons.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.