Rumford fireplaces have always scared me. Invented in 1796 by Benjamin Thompson, later Count Rumford, they are very tall and very shallow. They just look like more smoke is going to come into the house than up the chimney.
In fact the opposite is true. They were a revolution in fireplace design, burning wood far more efficiently and exhausting much more effectively. According to Wikipedia:
The Rumford fireplace created a sensation in London when he introduced the idea of restricting the chimney opening to increase the updraught. He and his workers changed fireplaces by inserting bricks into the hearth to make the side walls angled and added a choke to the chimney to increase the speed of air going up the flue. It effectively produced a streamlined air flow, reducing turbulence so the smoke would go up into the chimney rather than lingering and often choking the residents. Many fashionable London houses were modified to his instructions, and became smoke-free as well as more efficient. Thompson became a celebrity when news of his success became widespread. In an age when fires were the principal source of heat, this simple alteration in the design of fireplaces was copied everywhere .
I was surprised to see a prefabricated Rumford fireplace at the Interior Design Show in Toronto. Manufactured by Renaissance Fireplaces in Quebec, it is much shallower than a regular zero clearance fireplace, and has a guillotine sliding glass door that drops down in front. It is also very clean and efficient.
The key to lowering emissions is to achieve and maintain very high temperatures which allow volatile gases and particulates to burn. This is exactly how EPA certified, wood burning stoves burn cleanly, but making it happen in an open fireplace is much more difficult.
Impressive. More at Renaissance Fireplaces; a quick search showed that Rumfords are not so obscure at all, but are made by a number of different companies. There is a lot of information at Buckley Rumford Fireplaces.
Here is a copy of a video of the fireplace in operation; see it at higher quality on Renaissance's website.