As engineers, I think we're taught early on to pay attention to — and value — energy. We learn in physics to be wary of perpetual motion machines, that you don't get anything for nothing. In statics, free body diagrams teach us that every force has a resulting effect. Thermodynamics reminds us that after efficiencies are taken into account, you don't have as much to work with as you thought you did.

Maybe that's why my mind enjoys working to find easy ways to make my house more energyefficient, even environmentally friendly. We've switched over almost completely to compact fluorescent bulbs, which burn every bit as bright as the old ones, and use about one-fourth the energy. They are more expensive, but they have to be replaced much less often. The economics of this change really pay off in the long term ... you just have to start thinking about the long term instead of staring so much at the price tag while you're standing there in the home improvement store.

Another relatively easy change to make is to cough up $100-$200 for a digital thermostat. You can program your house to stay cooler while you're fast asleep, at work, or on vacation. Again, the savings you'll realize can quickly cover the cost of this product, especially given the heating bills of the past few winters.

My newest addition is one I'm particularly proud of, because it is one of those rare products that is so simple, yet so well engineered, you wish you'd have thought of it first. The Solar Powered Fan-Attic is a home attic ventilation fan powered by a solar cell, built right into the top of the unit. It is self-regulating, as the sunnier the day, the more the fan will run, exhausting hot air from attics as large as 1200 sq-ft.

Less hot, stagnant air in the attic means your air conditioner won't have to work as hard to keep your home cool, saving money. In the wintertime, the Fan-Attic runs less, but draws moist air from the attic outside, so condensation doesn't cause mold or mildew. And unlike normal attic fans, this one draws no current from your home's power supply. Another benefit is that installing it is about as simple as cutting a hole into your roof, as there is no wiring involved. That means more do-it-yourselfers can tackle the installation successfully.

For less than $400, I think the Fan-Attic will pay for itself in a reasonable amount of time, and I look forward to comparing my cooling bills from year to year. Check out more on the Fan-Attic at www.fan-attic.com

Beyond these simple things, many states — as well as the federal government — offer rebates, tax incentives, and the like to individuals or corporations who want to go the extra step and invest in solar cells or similar environmental energy sources. A handy list can be found online at www. dsireusa.org. Maybe part of your spring cleanup this year can include taking a fresh look at how to engineer your life to make it a little more energy efficient.