Environment: Butter-Pecan Builder

"Almost anyone will eat vanilla ice cream. But damn it, people get turned on by pistachio and butter pecan."

That is a rather unusual creed for a real estate developer. Butter-pecan houses? But Emil Hanslin, a weather-beaten, chain-smoking dynamo of 52, is an unusual developer. An early proponent of cluster housing, he is now experimenting with a new way to preserve open space. Says he: "It's a very simple thing but a big idea. The buyer buys the whole acre, but he gives up part of his land to the community. That makes him...