One. 

Late last year, R got some light bulbs from Costco, to replace three that fused in a period of a week. The bulbs she got weren’t the usual incandescent lamps but compact fluorescent bulbs made by a company I hadn’t heard of before. The lamp claimed to give more lumens of output for a fraction of wattage consumed (14W consumed for a 60W equivalent). I was intrigued. But, I also remembered the fluorescent lamps (tubes to be precise) that were extensively used in India while I was a kid. They flickered to life, required a bulky ballast and a starter. Some of them with lower powered ballasts took a while to come on. I was thus a little curious about these new bulbs which were small (to fit a large ballast etc.) and claimed to start up instantly, and since I try to be eco-friendly, I decided to give them a try. 

The bulbs light up almost instantly (0.25s or so) but are quite dim until it heats up, which is around 50-60 secs. Once heated, it provides a nice bright light, brighter than the equivalent incandescent lamp. 

A few weeks later, I came across an article in Fast Company titled "How Many Lightbulbs Does it Take to Change the World?". That article changed me. 

I took stock of the frequently used lights in my house and that weekend I was in Home Depot where I bought 12 compact fluorescent bulbs. I bought ones made by a company named n:Vision. I wasn’t happy with the ones from Costco and the n:Visions seemed better (product description wise) than the Philips that was in Home Depot. These are definitely better than the ones from Costco. They reach max lumens much faster and so far have lasted longer than the ones from Costco (two of the Costco bulbs died on me within weeks despite the fact that CFLs (compact fluorescent lamps) are supposed to last much longer than incandescent lamps (due to the lack of heated metal filaments)). They also have a choice of light quality from bright white to the dull yellow shadow lighting. 

Despite lighting up fast (relative to CFLs from yesteryear), they are still quite slow compared to incandescent lamps. Thus, in areas where you want instant bright light it isn’t ideal. At home, I replaced all the long-running ones (kitchen, living room, study, external lighting) with CFLs and in cases where I cared about instant light and where there were multiple fixtures, I left one incandescent bulb and replaced the others with CFLs. Gives me the instant light, but I end up saving a lot of power over time. CFLs are perfect for external fixtures which are lit all through the night. I still have a few incandescent lamps at home; those controlled by dimmers (haven’t found CFLs that like dimmers) and some in passageways where I need instant light but don’t remain on for more than a few minutes usually. 

I have 3 external light fixtures that are on through the night. Thus, during winter they are lit for around 10-12 hours every day. These were originally 60W bulbs that I have now replaced with 14W CFLs. Over the last four months, just those 3 bulbs have reduced my power consumption from 216 kilowatt-hours (60*3*10hrs*120days) to 50 kW-h (14*3*10hrs*120days) and probably $15 off my power bill. The bulbs are more expensive than incandescent bulbs (as of now) but last much longer. They also have trace amounts of mercury, so you need to recycle them appropriately. But, totally worth it. 

A few days back, I came across a news article about Australia banning (or phasing out) incandescent bulbs over the next three years. California is planning to do the same. Australia, Wal-Mart (see Fast Company article) and California can make a huge difference. But, I think we all can do our little part before legislation is passed (if at all). 

More about CFLs on Wikipedia.