Wednesday, July 2, 2014

The Thousand Year Old House

Why do we make and build so much of the things in our lives to be disposable? Our clothes, cars, appliances, furniture and even our houses? In 2011 the average age of a house in the US was 35 years. In Nevada it was only 19 years. The oldest average by state is in New York at 57 years. This doesn't mean that half of the houses of these ages will be torn down and replaced tomorrow, but it does indicate that a large portion of the houses in the US don't make it to their centennial birthday. The very oldest houses still standing were built in the middle to late 1600's making them about 350 years old. In contrast, there are houses in Europe that have been continually inhabited for the last 700 years. Now, part of this is due to the history of the European conquest of the Americas. But the Acoma Pueblo in New Mexico has been continuously inhabited since the twelfth century making it almost 900 years old.

Why is this important? Because building and making stuff consumes limited resources. This is important because we are quickly reaching the limits where these resources are being consumed faster than they can be replenished (have you bought anything made of mahogany lately?). Most things, like clothing, are impractical to make durable enough to last a lifetime (or several). But it turns out, a well built house that can last centuries, does not have to cost all that much more than one built to last only decades (they can, but it is not a requirement). The only question is why don't we bother?

Usually the answer is, it costs too much. But look at the oldest continuously inhabited building in the US in the picture above. It is essentially made of mud (adobe) and has lasted almost a millennium. Now, most of us don't aspire to live in mud huts, but it turns out you can make a very comfortable house that requires almost no energy to heat or cool out of mud, straw and sand for a fraction of the cost of a 'traditional' wood frame house. These materials shaped into bricks and baked in the sun are called adobe. Molded into a free standing wall that cures in place and it is called 'cob' (an old English term which means loaf, as in bread, about the size of each piece that is added to the wall one at a time).

So why don't we make all of our houses out of these materials? No wood to rot over time, get eaten by termites or that needs to be painted, scraped or stained every few years. OK, a cob or adobe house does have wood frames for the windows and doors, but those can be replaced if needed with little or no affect on the structural integrity of the structure. And some designs like the one above have wooden framed roofs. But some designs (domes and half-cylinders to name two) use the same material for the roof so have no shingles, roof repairs, leaks or replacement for the lifetime of the structure. And what is that lifetime again? Oh yeah, one thousand years. What was that reason why we don't make all our houses to last a thousand years?