I was shopping at my local grocery a couple of days ago and made an impulse buy. It was a "DLU" brand 23 watt CFL flood. With the Edison subsidy already reflected on the sticker, I got it for a cool 99 cents plus tax. At that price, it was too good to pass up.
I have only one floodlight in the yard. Since we're in the boonies, it gets downright dark on moonless nights, and we have critters from skunks to coyotes to bears in our neighborhood, so this light gets left on when we're away at night or plan to get back after dark. The flood light actually has two sockets; since the other one isn't needed, I keep a burned-out bulb in it to protect it from the weather.
After observing the brightness and pattern of the existing 75 watt incandescent, I swapped in the CFL. Turning on the switch caused it to glow dimly in the 33 degree night. Within about 30 seconds, there was enough light to see by. By about 90 seconds, it was at full brightness. While the color was a bit different, it definitely had the reach, brightness and wide pattern of the incandescent. Success! In this application, I definitely can live with the warm-up time.
When figuring the savings, I based it on 30 minutes of usage a day. It probably sees a little less on a daily basis, but when we go shopping, it will see one to four hours of use. At 30 minutes a day, it will pay for itself in about 6 months.
Outdoor flood light incandescent (75W) -> CFL (23W):
52 watts = 26Wh/day, 0.78kWh/month
Savings = $0.19/month, $2.25/year
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