When it comes to energy efficiency and keeping overheads low, changing old fluorescent tubes and halogens over to LED's can be with quickest way to achieve this.
LED lights can have a life span of up to 50,000 hours which reduces the need for changing globes and starters every couple of years not to mention the cost associated.
There is often a 50% reduction in consumption when changing over to LED and in some cases even higher like with LED Downlights which can be as high as 86%.
Changing over old Metal Halide High Bay lights to LED can improve efficiency not to mention reducing access costs when it comes to changing the globes etc. LED is often brighter and takes less time to light up than a standard Metal Halide fitting.