Photos: PowerPod is green and mod

The PowerPod is a modular green building with about 500 square feet of living space. Its creator, PowerHouse Enterprises, just signed on its first customer: the Yellow Barn Music School in Putney, Vt., which will be using eight PowerPods for its music lessons. The buildings come in a few configurations and cost about $100,000 each.

This demo model, originally built for a green building trade show, sits in a former coal-fired power plant in Lawrence, Mass., a city best known for its former textile mill industry.

From the outside, the most distinguishing feature of the PowerPod is its roof line, designed for both passive and active solar energy. Called the Solar Butterfly, the sloping roof allows sunlight in for heating and lighting during the winter months. The shorter south-facing roof holds a solar electric array and a hot water heating system.