I currently have 6 fluorescent lights (five foot each) in my garage.
If I’m updating these- do I need the same in LED or can I get away with less?
Lastly, can anyone recommend some good LED lights?
Most 5ft fluorescents lights emit about 2800 lumens of light. You will need LEDs of about 30w to match that. Check the spec of what you a thinking of buying for its output in lumens. 30w is about 3000 lumens.
Given the layout of your workshop and its area of 21m2, I'd estimate your 6 fls are emitting 17,000 lumens of light, but given 4 are against walls you are probably only getting about 70% of that light ie about 12000 lumens of light, maybe a bit less. This will give you an average illuminance at your bench of about 550 lux which is about right of a workshop, however as LED lighting is relatively cheap and long lasting and cheap to run, I'd recommend you up the illuminance by 10% or 20% overall. It will be higher under the lights against the wall, maybe as high as 1000lux under those fls.
For even lighting of your workshop, your current layout is a bit inefficient in terms of light output so a rearrangement may achieve a brighter effect. I presume you have sighted luminaires against the wall to give added light in those areas? If that is
not the reason, then I'd recommended a change to your layout by moving the lights that are against the wall into a more central position, if you space all the luminaires out evenly across the ceiling ie 2 rows of 3 you will achieve a better overall illuminance a 20 to 30% gain in overall illuminance at the bench. However you may want bright areas for certain tasks and local LEDs work very effectively at these locations as all the light is emitted down from the luminaire. So this is a matter of choice.
The technical terms are a bit confusing with lighting.
The light output from a luminaire is the luminous flux and is measured in Lumens. Roughly speaking you want to match the new for the old to achieve a similar overall light output. The light that is effective at the bench is the Illuminance measured in Lux and its just the luminous flux divided by the area. most background light in offices is about 300 lux and task lighting is nearer 500 lux. A desk lamp give about 750 lux ie bright over a small area.
As others have said check the colour temperature of your existing lights and if you like it match them up. I like a temperature of 4000k to 5000k i find below 4000k a bit to yellow and above 5000k a bit blue.
One last thing to consider is glare, if you find that your existing set up has a bit too much glare - which is caused by having a few very bright sources of light. Then you may want to get more luminaires that are a bit lower in brightness. That is go for 8 luminaires that are 2500 lumens rather than 6 at 3000. It will cost you a bit more to buy and install but the effect is nicer and less strain on the eye. If this is a major concern ie you get tired or headaches then you could lower the glare further with more dinner luminaires, they come in a range of brightness's these days.