Dear Vanessa,

I've been told that in order to realize true energy savings we should all be buying high power factor CFLs. What can you tell me about high power factor CFLs and where can I buy them?

— Andrew Keenan

Dear Andrew,

You must be referring to the issues surrounding displacement power factors, defined as the ratio of real power to apparent power. CFLs introduce a lagging power factor and out-of-phase current, which in turns leads to problems supporting a suitable harmonic characteristic and obtaining system savings. 

Got it? Me neither! After some serious deciphering, here’s my translation:

Those twisted bulbs that have become the symbol of all things green aren’t as eco-friendly as we thought.

The problem with compact florescent lamps or CFLs, aside from their mercury content, is the way they draw power from the energy grid. This isn’t something you would notice at home. You do save energy and money by using CFLs instead of the usual incandescent bulbs. In fact, CFLs can reduce wattage use by 75 percent and can last 10 times as long as an incandescent lamp. But the power grid doesn’t know that.

On the other side of the switch, or plug, CFLs ask as much of the power grid as incandescent lamps. Your utility company sends out the same amount of power to a 25-watt CFL as it does to a 100-watt incandescent lamp. While you only use and pay for the 25 watts, your utility company still has to produce and transfer the 100 watts. The unused power, known as reactive power, is partially wasted in the process of being transferred and re-transferred, and takes a toll on the infrastructure of the distribution system — overheating of transformers, cables and motors, premature aging of capacitors, and interference with telecom systems. Basically, our grids are designed to carry a certain type of energy (linear), and don’t provide power effectively to other kinds of energy demands (electronic).

What you’re hearing about — high power factor (HPF) CFLs — are an attempt to make up for the waste and stress on networks of regular CFLs.  HPF CFLS mimic linear demands and so make up for conflicts between how power is supplied and how CFLs use power.

So, yes, if you are going to buy CFL bulbs — and, compared to incandescent bulbs, you should — get the HPF CFLs. You get the same energy- and cost-saving advantages from both low and high power factor CFLs, but HPF bulbs have the advantage of saving as much as 75 percent of the network capacity required for incandescent lighting. That’s about 25 percent more than their low power factor predecessors. I believe the newer, high power factor bulbs also contain less mercury. Again, you won’t see the difference on your utility bill: high and low power factor CFLs deliver the same electricity savings to the user, so there is no immediate monetary incentive for you to buy HPF CFLs. It’s simply the better, greener, option.

HPFs are not widely available, yet, but you can easily find them online. Look for the best manufacturer’s warranty you can find (at least a two-year lifespan guarantee) and you probably want bulbs manufactured in the U.S. — or whatever country you’re in — as they are more likely to function correctly with your power distribution system. Of course, you'll also want to support manufacturers that provide safe, dignified working conditions and a true living wage to their employees ... and have ecologically sound production, packaging and transportation practices ... and support a healthy, local economy ... and did I mention living wages?

Lightbulbs to living wages … aren’t you glad you asked? Now, about LEDs …

Of course, no matter your choice in bulbs, changing your consumption habits is what will really make a difference.

Keep it Green,


What's up with high power factor CFLs?
High power factor compact fluorescent light bulbs are a better choice than standard CFLs because they put less strain on the power grid.