Estimate streetlight retrofit savings with clear project inputs. Compare energy, demand, and yearly maintenance costs. Plan budgets, cut emissions, and justify upgrades today confidently.
| Scenario | Fixtures | Existing (W) | New (W) | Hours/night | Rate | Annual kWh saved | Annual $ saved |
|---|---|---|---|---|---|---|---|
| Collector road upgrade | 80 | 150 | 70 | 11 | $0.12 | 28,864 | $3,464 |
| Residential corridor | 120 | 100 | 45 | 10 | $0.10 | 24,090 | $2,409 |
| Highway interchange | 60 | 250 | 120 | 12 | $0.15 | 34,164 | $5,125 |
Streetlight energy use is driven by fixture wattage, quantity, and operating hours. In most municipal corridors, lights run 10–12 hours nightly, producing 3,650–4,380 annual hours. A 150 W legacy fixture operating 4,015 hours uses about 602 kWh per year. Scaling by 100 fixtures yields roughly 60,200 kWh annually, before demand or maintenance costs.
Replacing legacy luminaires with efficient units reduces input power while maintaining illumination targets. If wattage drops from 150 W to 60 W, annual energy per fixture declines to about 241 kWh, saving roughly 361 kWh each year. Multiply by fixture count to quantify portfolio savings. When tariffs include demand charges, the coincident factor estimates how much kW reduction aligns with the billing peak interval.
Ongoing maintenance often rivals energy savings in older systems. Lamp replacements, ballast failures, bucket-truck mobilization, traffic control, and callout labor add recurring costs. LED retrofits typically reduce relamping frequency and troubleshooting visits. Enter per‑fixture annual maintenance for existing and new systems to convert reliability differences into yearly savings that improve payback and net present value.
Installed cost per fixture should reflect materials, removal, disposal, controls integration, and commissioning. Incentives and rebates reduce net project cost; apply them per fixture to keep calculations transparent. Simple payback divides net cost by total annual savings. For capital planning, NPV discounts the annual savings stream over the analysis horizon, allowing consistent comparison across competing infrastructure upgrades.
Emissions avoidance depends on the grid’s kg CO₂ per kWh factor. Multiply annual kWh savings by the factor to estimate avoided kilograms, then convert to tonnes for reporting. Use local factors where available, especially for project financing or sustainability disclosures. Export results to CSV for spreadsheets, or PDF for submittals, audits, and stakeholder briefings. These estimates support grant applications, public dashboards, and transparent performance tracking over time.
Use the measured input wattage when possible. If you only have lamp ratings, add typical ballast or driver losses so the baseline reflects real power draw.
Use photo‑cell logs, control schedules, or seasonal averages. Many systems run 365 days, with 10–12 hours nightly depending on latitude and dimming strategy.
Include them if your bill has a $/kW line item tied to peak demand. If streetlighting is separately metered without demand billing, set demand charge to zero.
It estimates what share of the lighting load reduction occurs during the billing peak window. Use 0.6–1.0 if lighting is on during typical peaks.
Convert your work history into annual cost per fixture, including lamps, parts, labor, traffic management, and dispatch. Use a conservative LED value if warranties apply.
Payback is sensitive to tariffs, run hours, net cost after incentives, and maintenance assumptions. Recheck units, fixture counts, and whether the new wattage is realistic.
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.