April is Earth Month. If you have your light on for 3 hours a day, these will pay for themselves over the first year and you will also contribute to saving our planet.
The math is simple. Average cost of electricity is $0.10/kW plus around the same for distribution. So if we put the price of electricity at $0.20/kW, and you use your 60W incandescent bulb every day for 3hrs, this bulb will pay for itself in around 9month. Math (60W x 3HR = 180W = 0.180kW * $0.20 = $0.036/day for the 60W bulb at 3hrs/day. 7W x 3HR = 21W = 0.021kW x $0.20 = $0.0042/day. $0.036-$0.0042 = $0.0318 or roughly 3 cents per day in savings. You will save around $11+ in electricity PER LIGHT BULB PER YEAR, and won't have to replace them for a very long time.