Despite my earlier rantings, I do appreciate a bit of night time lighting around my home for the purposes of security-- and entertainment. After all, its rather interesting to see what sorts of amazing insects naturally gravitate to the light (like the occasional sphinx moth!) and the nocturnal predators that show up for the evening buffet.
Two fixtures currently illuminate the outside of my home: one street lamp and an outdoor porch light. I have long since switched out the incandescent bulbs in each in favor of compact fluorescents. At the moment, there are three13-watt bulbs over the porch, and two 15-watt flood lights powering the street lamp. Last year, on average, I would say the lights burned a total of perhaps three hours every night. Thus,
13 watts + 13watts +13 watts + 15 watts +15 watts = 69 watts
69 watts ÷ 1,000 = 0.069 kWh
0.069 kWh × 3 hours = 0.207 kWh/day
0.138 kWh/day × 365 days = 75.55 kWh/year
Not a lot of juice, really, since the fixtures already use efficient bulbs. But a recent trip to BJs made me think there might be a better way...