Can a house where wood is burned for heat really be called green?

Scott JacksonComment

After writing From the straw bale wrap to the lime plaster finishes, this cottage is as green as it gets there was a huge pushback from commenters who complained about the use of wood for heating.

"...as green as it gets"? I would like to respectfully disagree. It's unfortunate that "renewable" is now equated with "clean", "green", "healthy", and "good-for-the-planet".Yes, wood is renewable, but burning it as fuel has none of these positive attributes.

And that was the one respectfully disagreeing. TreeHugger has never been in the “renewable is green” camp, complaining forever about biofuels and yes, biomass heating. But this is different.

It is an issue we have looked at in TreeHugger before, asking Is burning wood for heat really green?, where I concluded that it really isn’t. Yet lots of very green people do, including Alex Wilson, founder of BuildingGreen, who knows more about the subject than anyone I know. So let’s look at the issue in terms of this particular house.

  • The house is designed for efficiency first. It is almost passive, meaning that it doesn’t need much heat at all. So unlike those houses in Fairbanks Alaska, where they are piling wood into giant boilers and the air quality is worse than in Beijing, this is a tiny wood stove. Just look at in the photo.
  • There are very few neighbours and extremely low population density. As noted in my previous post, wood doesn’t scale, it is not a suitable solution for a lot of people living close together. But a single house, used part time, in the middle of a forest?
  • The alternatives aren’t pretty either. Some commenters suggested an electric powered air source heat pump. A heat pump is an air conditioner running backwards in winter, but this is in cottage country and you do not want air conditioning. So it is just for heating. The average winter night-time temperature is 0°F, at which point heat pump efficiency drops way off. The alternatives are bottled propane (an expensive fossil fuel) or electric resistance heating. But the electricity supply is erratic; lines are often downed by storms and trees falling. You cannot rely on it.

A few years back it was a standard argument that wood, being renewable, was a greener source of energy than fossil fuels. Environmental writer Mark Gunther called it A renewable energy technology that gets no respect. He called it " a "green" technology that appeals to poor and working class people. And, because gathering and distributing wood is labor intensive, it's generates economic activity."

But that was before we began to realize what a big problem particulate pollution really is. The very impressive Families for Clean Air website spells out the dangers, particularly in urban areas. Sam Harris is pretty convincing too. They are not alone in complaining; Government sources like the Province of Quebec note that wood burning is the single biggest source of fine particles emissions, and how dangerous they can be:

Among all particles emitted by wood heating, the ones whose aerodynamic diameter is equal to or less than 2.5 micrometres (PM2.5) are of most concern for health. These suspended particles are so small that when inhaled, they cover the surface of the pulmonary alveoli and impair gas exchange, which impacts the respiratory and cardiovascular system by, for example, aggravating symptoms of asthma through the irritation and inflammation of the bronchi. Winter smog, of which residential wood heating is a contributing factor, is mainly comprised of fine particles

It is recognized as a health hazard, and as I noted in my earlier post, wood heating doesn't scale, and we shouldn't burn too much of it. But the Lake of Bays area is not San Francisco Bay area, where the Families For Clean Air people are located. It is a different world.

I remain convinced here, as I do with net zero energy projects, that what source people use for energy is far less important than how much they use. When you design a house that is almost passive, the amount of fuel used for heating is negligible. As the architect, Terrell Wong notes, " Reducing your need for heating 90%.------Then occasionally having a fire in an uber efficient German boiler is not a bad thing." Every fuel has a carbon and a health footprint, either at the source or at the point of use.

Given the location, the climate and the alternatives, I believe there is a plausible case for wood.

http://www.treehugger.com/energy-policy/can-house-where-wood-burned-heat-really-be-called-green.html