Plan brighter yards while cutting energy waste today. Switch to efficient fixtures and save annually. See payback time, totals, and charts in seconds here.
| Scenario | Fixtures | Existing (W) | New (W) | Hours/Night | Rate | Annual Savings | Payback |
|---|---|---|---|---|---|---|---|
| Driveway + garden | 12 | 100 | 20 | 8 | 0.18 | ~504.58 | Varies by upfront cost |
| Commercial perimeter | 60 | 150 | 45 | 10 | 0.15 | ~3,449.25 | Often 1–3 years |
| Park pathway | 40 | 80 | 18 | 7 | 0.12 | ~760.37 | Depends on labor savings |
Outdoor fixtures often run 6–12 hours nightly, so annual operating time can exceed 2,000–4,000 hours. At 8 hours for 365 days, this calculator uses 2,920 hours. Multiplying wattage, fixture count, and hours converts to annual kWh, helping you compare steady nightly loads against other building uses.
If 12 fixtures drop from 100W to 20W at 0.18 per kWh, energy savings are about 630.72 each year: (80W × 12 × 2,920 ÷ 1000) × 0.18. Larger sites scale quickly; 60 perimeter lights dropping 150W to 45W at 0.15 per kWh can save about 3,445.50 annually from energy alone.
Outdoor systems face weather, vandalism, and access costs. A single lift rental or night callout can outweigh weeks of electricity. This calculator separates annual maintenance for existing and new fixtures, so you can reflect longer lamp life, fewer driver replacements, and reduced labor frequency in the total-cost comparison.
Simple payback divides upfront cost by annual savings and is easiest for quick screening. Many projects target 1–3 years for commercial sites and 3–6 years for residential upgrades. When savings are negative or near zero, payback is shown as N/A, signaling that wattage, hours, or pricing assumptions need review.
NPV estimates value over a chosen horizon by discounting each year’s savings. Using a 6% discount rate across 10 years, the present value of 1,000 annual savings is about 7,360.09, and NPV equals that amount minus upfront cost. Use NPV when comparing options with different lifespans or higher first costs.
For accuracy, align wattage with real driver draw and include control strategies. Photocells, dimming, and motion sensors can cut effective hours by 15–50%, improving savings without changing fixtures. If your tariff includes demand or time-of-use pricing, use a blended rate or run scenarios. Add realistic installation cost, then export CSV or PDF to share assumptions with stakeholders.
Recheck inputs annually as rates, hours, and maintenance practices change often.
Indirectly. Reduce “Hours per night” to your expected effective runtime. For dimming, enter the average wattage draw or run two scenarios and compare annual savings and payback.
Use a blended all-in rate from your bill, including riders and taxes if you want a cash estimate. For time-of-use plans, model a weighted average or run separate cases.
Outdoor lighting often requires ladders, lifts, or after-hours labor. Capturing annual maintenance for old and new fixtures can materially change total savings and shorten payback.
Negative savings means the new setup costs more annually under your inputs. Check wattage, hours, tariff, and maintenance assumptions. Consider controls, fewer fixtures, or a different product specification.
NPV equals the discounted value of each year’s savings minus the upfront cost. Increase the discount rate to be more conservative, and extend analysis years to reflect longer service life.
Yes. Use the CSV for spreadsheets and the PDF for a simple report. Keep inputs realistic and note assumptions like hours, seasonal use, and maintenance frequency.
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.