Retrofitting vs Replacing

Knowing Your Options in a Commercial Office Setting

Commercial Office SettingYour commercial office setting needs to be upgraded. You ask yourself, do I retrofit or replace the current lighting system? Should I replace it with T5 fixtures or T8 fixtures? These questions come about often. Let’s look at your options.


Many designers will use a 28 watt T5 in this setting as it is deemed to be one of the newer technologies. I would prefer to design the system with T8 technology. These 28 watt T5 lamps put out less lumens of light than some T8 lamps, yet they cost upwards to three times as much as a T8 lamp. Lamp life is the next item to consider. A high lumen T8 lamp, which has many wattage and color options to choose from, has a rated life between 36,000 to 46,000 hours based upon 12 hours per lamp startup. The T5 lamp is rated for only 20,000 hours following the same criteria and has no options to choose from, short of their color. The ballast for a T5 lamp costs three times more than a T8 ballast costs. T5 ballasts also have no other energy saving options, while T8 ballasts have at least four power options to choose from.

The next item to review is the temperature of the environment. Keep in mind that an office environment usually maintains an average temperature between 70 to 75 degrees year round. Most T8 lamps produce 99 percent of their lumen output at 75 degrees Fahrenheit. The standard T5 lamps produce only about 80 percent at 75 degrees Fahrenheit and 100 percent of their lumen output at 95 degrees Fahrenheit.


Retrofitting will always be the more cost effective option. Let’s look at a four lamp grid style fixture as it is quite common in an office setting. I see people de-lamping these fixtures down to two lamps just to achieve savings. While this may seem a logical, simple solution, the lamps are usually spaced to the inside and outside of the fixture. What most people don’t realize about fixture efficiency is that the fixture, when it was new, had about a 75 to 80 percent efficiency rating. This means is that 75 to 80 percent of that light is getting out of the fixture and the other 20 to 25 percent is lost and is not being dispersed into the area. The average fixture that is 20 to 30 years old is probably somewhat dirty and the white surface inside the fixture may be deteriorated. Because of that, the efficiency may have fallen to 50 to 60 percent as it is reflecting less light out of the fixture. When only two lamps are installed into the fixture, you are decreasing the efficiency even more, maybe as low as 40 percent, because the fixture is not providing uniform light anymore.

In regards to retrofitting, there are reflector kits designed to space the lamps evenly inside the fixture and bring the efficiency upwards of 90 percent. This is also true for many different fixture types. New fixtures are designed at a higher efficiency rating than fixtures made in the past.

So which is the right decision – retrofit or to replace your current lighting system? There is no one correct answer. The question you should ask yourself is what do you expect from a completed project? Do you want an updated look? Do you want to save money? Once you determine this, you can make an informed decision.