A bit of mathematics at the end of the week. The

The first table shows three different installations. The old one is equipped with T8 fluorescent lamps that are at the end of their lifetime and dirty. That is why the luminous flux is so low for the 60W tube. In this situation, the need for a replacement is present. The choice is between a fluorescent tube, a LED tube or a completely new installation with controls. Controls reduce the average power consumption to 1/3 and less of the original load. We can estimate the new fixtures will consume 12W only when connected to controls that detect presence in the hall and reduce the lighting level in areas that are not in use. Each light point will be replaced. It is (often) possible to reduce the number of fixtures with a new installation. The example is concentrating on a one-by-one replacement to make it easier to understand.

The table above shows the sum of all costs for running and maintaining the installation each year and in total. The Retrofit Solution reaches an ROI after 2 years already. The New Installation with controls is going to turn back the high investment after 10 years. Both LED solutions do better than the conventional one, save energy and CO2 emissions. Let’s go green with LED light sources!