No matter whom I speak to about green building, the conversation always seems to circle back to what I and many consider to be the most important aspect of a sustainable home: durability. It's a term I define broadly as a house built using proper installation techniques, with an awareness of building science principles and the right combination of products and details that will keep it leak-free, mold-resistant, and rock solid for years to come. I'm reminded of this every time I marvel at a historic brownstone here in D.C. or see pictures of centuries-old white houses on the seaside cliffs of Greece.

Simply put, a poorly constructed house should not be considered green. If a house can't keep moisture from causing damage, no amount of Energy Star appliances, insulation, or photovoltaics is going to do much good or reap its fullest potential. Certified lumber won't save much if it's got to be demo-ed in 20 years. Nearly every aspect of green building relies on the firm foundation of a firm foundation.

Of course, building durable homes is certainly not a green building-only principle. It is and always has been the basis for successful "building." Quality has always meant better performance, fewer callbacks, and a stronger reputation that increases word-of-mouth referrals.

If a housing slowdown gives us anything beneficial, it's a chance to get back to basics. The time to educate ourselves on the latest building science techniques. The chance to make sure our crews understand the fundamentals of proper installation and to help them re-focus on important details. The opportunity to instill a culture of accountability among staff.

If you're new to green building, start with--or at least freshen up on--the fundamentals of building science. Master building smart before you implement anything else.

A truly green home is one that will stand the test of time, long after its faucets have gone in and out of style and its keys have changed hands across generations. Durability is simply building right. And who can afford to be wrong?

Katy Tomasulo is Deputy Editor for EcoHome.