Buying Energy Star PCs is the right thing to do for the environment. Some companies take that responsibility seriously. But at companies only concerned about saving money, the EPA's brand new energy-efficiency requirements won't dazzle the accountants.

We did a big story on Green Computing this year ("What Every Tech Pro Should Know About Green Computing"), and the takeaway was that companies want cost savings, not just a feel-good, eco-friendly vibe.

So check my math here. The EPA estimates a company can save $2 to $10 a year in electricity running an Energy Star PC. Assume the typical lifecycle for a business PC is three years-so you're saving $6 to $30 lifetime. Manufacturers tell the EPA the new power supplies will add about $30 to the cost of PCs. So you're lucky to break even. Even stretching the life cycle to five years, the median savings of $30 is about break-even.

This isn't knocking the EPA. Only 20% of computers meet this standard today, so it has raised the bar for PC makers. And the EPA thinks the price of those more efficient power supplies will fall with bulk orders, and there's no reason to believe it won't. So the math should get a bit more compelling. The EPA estimates Energy Star PCs will save companies and individuals $1.8 billion in energy costs the next five years.

But for IT buyers, the Energy Star requirements could end up being about a wash on upfront cost versus energy savings. Hopefully that'll be enough to convince most companies to buy based on energy efficiency. And even more important, let's hope PC makers don't settle for the Energy Star standard when it comes to energy efficiency, and they'll deliver even higher electricity savings.