I have a 24 X 36' garage/shop that came with the old T-16 florescent tubes 4' long. Four fixtures total- one over each of the three garage bays, one over the work bench. In cold weather, you could barely see inside. Wasn't real happy, but couldn't do anything about it at the time.
In 2015, after some research, upgraded to T-8 florescent bulbs and doubled the number of fixtures to eight. Much better. Slight dimming in the winter, but not nearly as bad as the T-16, and doable.
In 2018, was out in my 12' X 16' storage shed at my parent's place doing some reloading and shooting before deer season using a "trouble light" with a 100 watt incandescent bulb to light the up the building and using a clamp on flexible stand with another 100 watt bulb over the work bench. Dad came in and said, "Here, I'll let you borrow this".. it was a 4' LED light rated at 5500 lumens. HOLY COW! It lit that room up all by itself! It is instantly bright and does not dim in cold temperatures, unlike florescent.
I was wondering, since my T-8 florescent and the LED were both rated at 5500 lumens, why the LED was so much brighter? So I did some research. Turns out that the florescent gets that rating by measuring the light put out all the way around the bulb, a lot of which is recessed in the fixture and does you no good. Plus, it slowly loses its brightness over time until it goes dark. So if yours is a few years old, you're not getting the full rating on the part that does shine out. LED on the other hand, is essentially measured on all of its usable light, plus it doesn't dim until it finally quits.. many years down the road.
This past spring (2020) I redid all my garage/shop lighting and added two more for a grand total of 10- 4' LED lights with 5500 lumens each. It lights that place up like the Fourth of July. There is no way I would ever consider going back to florescent.
