Monday, 2 December 2013

Walking to an eco house?

A colleague recently asked where I parked. Parking is very draconian where I work, and a big issue for drivers. I told him I didn't drive to work, but came by bicycle, bus or on foot. This surprised him as he knew I had an eco house, and assumed it was somewhere in the mountains.
There seems to be a perception that eco houses should be deep in nature, perhaps in primeval rain forest, and accessible only by Tarzan swing or four-wheel drive. My house is a ten-minute walk from the city station and a twenty-minute bike ride to work. And I suppose eco houses have the image of being off-grid and self-sufficient, but why be off grid if there's a chance of supporting a smart grid? Urban living has less impact on the planet than rural living, if you look at it per capita.
There is a sense that The System is destroying the planet, so in order to stop destroying the planet you need to get out of The System. But you're still going going to have an impact on the planet if you leave the system, and we stand a much better chance of survival working together than seven billion people, and counting, going off on their own.
Anyway, I don't really understand how it would be an eco house if I had to drive to work each day from it. Back to carbon accountancy and walking to work, if I was to drive the 4km to and from work each day, something like 250 days a year, and with my car doing 10 km to the litre, that would use about 200 litres of petrol per year, emitting half a tonne of CO2. That's already over half of my share of the 2.7 tonnes the house emits a year. Build an eco house in the wilderness and you risk blowing all the benefits commuting from it to work.
I know it's not a terribly efficient car, but it was second hand, and I reasoned that since we drive so little, it was much better for us to get an inefficient car than for somebody who was going to be driving it every day to buy it. I'm not exactly sure my logic is sound here, but anyway, I'm not going out to buy the latest super-efficient hybrid just to write this post.
According to some websites, walking and riding a bicycle produce no carbon at all, but once again it's not so simple. If you walk to work, you're using your body as a machine, and the fuel going in is the food you eat. If you were to grow all your own food, use local, natural fertilisers, and pick it by hand, then you'd be carbon neutral.
In fact the production of food is not at all carbon neutral. From preparing the ground to harvesting crops and from sowing seeds to stacking the packaging on the shelves, energy is being used. The industrial production of ammonia and its use as a fertiliser are now an essential part of the supply of food to our growing and greedy population, and we probably could no longer survive without it. Our dependence on oil is so great that we are virtually eating it. You can see more details here on about the carbon footprint of different diets, and some in depth comparisons here on On a very rough average, every calorie of food we eat has used a calorie of oil to produce. So the calorific content of food is not just the number of calories inside it, that are organic in the chemical sense that they are based on life, and carbon-free in the climatological sense that they have a net zero effect on CO2 levels.
It also depends what you have for breakfast. If you're eating food flown half way around the world, or your diet consists of large amounts of beef, walking or riding a bicycle could actually be producing more carbon than driving.
Bicycles are much more efficient at turning our energy into food than walking, so on the surface that's going to be low carbon. We have to think about the cost of the bicycle itself though, even though I have a bike anyway, and it's not going to make much difference whether I use it or not. But we do need to factor in the capital cost of the technology into the running cost of the calories in our food.
Which reminds me, if you're going to treat your food as carbon neutral, you shouldn't be using any iron tools either.
Of course you could argue that you'd be eating all that food anyway, and you shouldn't be looking at it as an extra environmental cost, and it's certainly true there are plenty of people sitting in cars who eat as much as cyclists. Some of them are even driving to the gym to burn off all those calories in an oil-heated pool or on an electrically-driven treadmill. This may be a rather ridiculous exercise, but I think any attempt to assess our impact on the planet is worthwhile
And sometimes I get the bus. I'm not exactly sure how to calculate the carbon for that. I could take the view that the bus is moving anyway, so it's just the extra carbon used to carry my weight. This may be close to the truth when it's packed and I'm standing at the back, but sometimes I'm the only person on the bus. In that case, it's going to be doing a lot less than 10 km to the litre and I'd be better off driving my own car.
I'd really like to find a definitive answer to how much carbon each of these transport options produces, but I've already spent enough carbon surfing the web without an answer, so I think the definitive answer is that there isn't one. Just, rather obviously:
  • walking and cycling are better than driving
  • if you're going to drive, living close to where you work could make a bigger difference than building an eco house
  • if you're concerned about the environment avoid eating beef.

Also, if any bus companies are reading, you should consider providing taxis instead of buses for off-peak routes, since it would reduce carbon and your bottom line.

If you are want to know more about the carbon coming out of your food, you may be interested that in 2007 the Guardian reported Tesco's plan to label all their products with a quantified carbon footprint, only to report in 2012 that  they had dropped the plans. is still working on it though.