Almost all Americans have shopped in a "big box" discount store.

"Big box" stores are designed to keep building costs down and to keep up with changing tastes. Remodeling is anticipated every five to seven years, obsolescence after 15. In comparison, suburban office buildings are typically designed to last 30 years, while many skyscrapers built in 1930 remain in service today.

Next time you're shopping, look around the facility and consider its permanence and sustainability. The potential lifespan of that building, long or short, is part of its design.

How long should structures last? A structure too well built may be difficult to adapt to new uses. A structure poorly built will not function well. Without regular maintenance, nothing functions well for long.

The idea of permanence is full of contradictions.