The power consumption of a 4-lamp T5 is indeed far less than a conventional 400W metal halide. The metal halide consumes 400W for the lamp and another 50 or so for the ballast for a total of 450W. The T5HO fixtures consume 54W per lamp plus another ~17W for the ballast for a total of 233W. That’s almost 50% less power for the T5HO fixture. The important thing is what those two fixtures do with the power they consume. The lumen output of the standard metal halide lamps starts to decay very sharply as soon as it’s put into service, but the lamp continues to draw the full 450W of power until the day it finally fails. The T5HO lamps not only decay much more slowly (due to lower mercury content), but also put out much better quality light. The human eye is an amazing thing. Even if the absolute quantity of light on a surface may be a tad bit higher, the fact that the the light is more natural makes the eyes adjust much better to it.

T5 and T5HO lamps are made using rare earth phosphors that improve color rendition and lamp performance. As for the mercury question, they do contain minor amounts of mercury. TCLP compliant T5HO lamps can have as little as 1.4mg of mercury per lamp for a total of 5.6mg for a 4-lamp luminary. Metal Halide, by contrast, contains upwards of 60 to 70mg. For comparison, the mercury content in standard T12 lamps can be as high as 30mg per lamp! TCLP is a test designed to simulate what happens to a product if it is disposed of in a landfill. The government sets limits for the amount of mercury that can leach out of the product in that condition. All major manufacturers product T5 lamps that pass this test. There are also a number of ways to recycle these lamps without sending them to a landfill.

Hope that helps.

T5 and T5H0 based fixtures are certainly growing in popularity for lighting warehouses, manufacturing facilities and any other application with high ceilings, but there’s a long way to go. Most building owners don’t realize they could significantly improve their bottom line just by switching out the lights in their warehouses. These fixtures use 50% less energy than the standard metal halide high bays. When you realize that on average, 40% of electric consumption is on lighting, these fixtures can reduce the bill by 20% or more. For a typical warehouse, that can be $30,000 or more.

To sweeten the deal, many utility companies and state agencies provide significant cash rebates to customers that undergo a lighting retrofit project. This is done as a way of managing demand in states with limited generation capability. These rebates coupled with $0.60 per square foot tax deductions made available through the Energy Policy Act of 2005 make lighting retrofit projects one of the fastest paying projects that a facility can undertake.

At Relight with T5, we’re passionate about helping to reduce our impact on the environment. I appreciate the mention and I hope it helps get the word out throughout the industry.