Each hut utilizes a contained composting toilet system, solar power, and radiant floor heating powered by a wood boiler.

And next month, the Environmental Protection Agency expects to issue guidelines for states to follow in regulating the use of wood boilers.

In the last two years, outdoor wood boilers have doubled in number, to about 150,000 nationwide.

It is designed to replace the often-banned, traditional outdoor wood boilers.

Most of the campus's heat is generated from a wood boiler which burns wood chips, a renewable resource.

The wood boiler is the only industrial infrastructure in the sector.

The outdoor wood boiler is a variant on the indoor wood, oil or gas boiler.

An outdoor wood boiler works by heating a water jacket that surrounds the firebox.

Outdoor wood boilers are a topic of environmental controversy.

Currently, very few outdoor wood boilers have been submitted to this test, making it harder for the consumer to make informed environmental choices.