| Typical system efficacy | Approximately 60–80 lm/W | Approximately 80–140 lm/W for lamp efficacy; system efficacy is lower after ballast and optical losses | Approximately 100–180 lm/W for modern outdoor systems | Induction can reduce energy use in retrofit projects, but a photometric comparison is required before selecting it over LED. |
| Rated operating life | Commonly 60,000–100,000 hours, depending on lamp and ballast design | Typically 20,000–30,000 hours | Commonly 50,000–100,000 hours, subject to rated temperature and lumen-maintenance conditions | Long-life technologies reduce relamping visits, especially on remote roads, bridges, and highways. |
| Expected energy reduction versus HPS | Often about 25–45%, depending on existing wattage, optics, operating hours, and light-level requirements | Baseline reference | Often about 40–70% in well-designed replacements | Use measured load profiles and maintained illuminance—not wattage alone—to calculate savings. |
| Light quality | Typically neutral to cool white; CRI commonly around 80 or higher, depending on lamp specification | Usually warm light with relatively low color rendering; standard HPS is commonly around CRI 20–30 | Typically available from CRI 70 to 90 or higher | Induction is suitable where improved color recognition is needed but advanced controls are not essential. |
| Warm-up and restrike behavior | Near-instant starting; generally suitable for frequent switching | Requires warm-up and may require several minutes to restrike after interruption | Near-instant starting and restarting | Induction is advantageous in areas with unstable grids, frequent outages, or motion-based operation. |
| Dimming and controls | Dimming may be available, but compatibility and dimming range depend on the generator and ballast | Limited compared with modern digitally controlled systems | Wide control options, including scheduled dimming, sensors, and network monitoring | Select induction when basic reliability is more important than advanced smart-city functionality. |
| Maintenance requirements | Low relamping frequency; electronic generator and thermal management still require inspection | More frequent lamp and ballast replacement | Low routine maintenance, but complete fixture replacement may be required if the LED module is not serviceable | Induction can be attractive where maintenance access is expensive or hazardous. |
| Environmental considerations | Contains mercury and requires controlled recycling at end of life; lower energy use reduces operational emissions | Contains mercury and generally has higher replacement frequency | Normally mercury-free; embodied impacts depend on materials, manufacturing, and replacement policy | Induction projects must include lamp take-back, spill prevention, and hazardous-waste procedures. |
| Temperature suitability | Generally stable across a broad outdoor temperature range when correctly specified | Performance varies with ambient temperature and ballast condition | Often performs well in cold environments, but heat management is critical in hot climates | Review the complete temperature rating, enclosure design, and expected nighttime climate. |
| Best-fit project types | Road and area-lighting retrofits, industrial yards, tunnels, ports, campuses, and locations with difficult maintenance access | Existing installations where low initial modification cost is the main priority | New construction, high-efficiency upgrades, connected lighting, and projects requiring precise optical control | Choose the technology according to light distribution, controls, serviceability, environmental rules, and total cost of ownership. |
| Key procurement checks | Photometric files, total system wattage, lumen maintenance, ballast life, ingress protection, surge protection, mercury handling, and local conformity certification | Lamp wattage, ballast compatibility, restrike performance, and replacement availability | TM-21 or equivalent lumen-maintenance data, thermal rating, driver life, surge immunity, controls compatibility, and serviceability | Require a site-specific lighting simulation and a life-cycle cost model before contract award. |