A freebie to you all: My protocol for calculating a cost benefit analysis for LED vs. Incandescent lamps in a LV Outdoor Lighting System. Assumptions: 1 - Incandescent source is a 20W load that has a field life of 3000 hours. 2 - LED source is a 6W load that has a field life of 35,000 hours. 3 - I will leave the cost sections blank for you to fill in with your prices for your market. 4 - Be sure to include the 'real cost' of electricity in your market. This includes the electricity, delivery charges, debt retirement charges, surcharges, taxes, etc. (Take your household bill and divide the total number of KWh used into the total amount of the bill) Per Fixture Cost of Operation: Halogen Lamp A: (20W X 35,000 hours) / 1000 = Total KWh consumed X $ per KWh = Cost of Electricity used by Halogen lamp for the purposes of this analysis. B: 35,000 hrs / 3000 hrs = 11.6 Lamp Changes X $(cost of lamp to client) = Total Lamp Change Cost to client. C: Man hours labour per lamp change X 11.6 Lamp Changes X Labour Rate = Total Labour Cost to to client. Add up A+B+C = Total Cost of operation to the client for Halogen Lamp for 35,000 hours of operation. LED Lamp A: (6W x 35,000 hours) / 1000 = Total KWh consumed X $ per KWh = Cost of Electricity used by LED lamp for the purposes of this analysis. B: Initial Cost of LED Lamp. Add up A+B = Total Cost of operation to the client for LED Lamp for 35,000 hours of operation. Cost Benefit Calculation. Subtract the Cost of operation of the LED Lamp from the Cost of operation of the Halogen Lamp. The remainder is the savings the client will realize per fixture if they choose to go with the LED lamp over the lifetime of the product. In my market the client stands to save over $200 per fixture when they choose the LED lamp. If the lamps actually last the 50,000 hours that the manufacturer is claiming ( I am de-rating them to be 'safe') then the client will see a savings of $340 per fixture in my market. This calculation can be easily adapted to your market and other LED technology by changing the variables and costs. Have a great day.