While a full replacement of an entire is fixture is very valid to do, especially when they are outdated or literally falling apart, often times you can avoid that by retrofitting your fixtures. With retrofitting you get to keep your old fixture but just replace the light source in it with a new one. This will allow you to reduce the costs associated with the lighting upgrade tremendously, which will allow you to realize a much larger ROI. Although there are benefits of both, you should consider your facility or buildings own situation and go from there. To recap, retrofitting is great if you can keep your old fixtures, but if you can’t, (due to reasons like outdated or near falling apart), then a full replacement is probably the better option.