My last blog post was about a free online version of Making Better Building by Chris Magwood. In reading through some of his introductory comments about foundations, I came across this statement: “In much of North America, foundations have been twinned with conditioned, subgrade living space: the basement. In many markets, having a basement is so normal that it can be hard to convince a homeowner to imagine a house without one. It is difficult to create a sustainable basement and — unless the home is in the driest, best draining of soils — impossible to create a basement that doesn’t rely on several layers of petrochemical products to stay dry”
While I agree that there are definitely challenges in building ecological basements, I question his suggestion to avoid them altogether. From my perspective the value of below-grade living space is extremely high, what with the moderating effect this has on creating comfortable living temperatures, and thus the energy inputs required for both heating and cooling the space. Nearly everywhere on Earth digging into the ground has the potential to save energy and create more comfort. I consider it one the most sustainable of all building practices, especially as we go forward with our changing climate.
So I wrote to Chris and asked him what he thought about this.
This is his response:
I agree with you on a conceptual level… there are definitely benefits to being below grade to some degree or another. That’s why I don’t say to avoid these spaces altogether, but rather that using “bad” materials is typically necessary. I don’t want to greenwash the idea, because in a North American context it’s nearly a guarantee that concrete, foam and toxic coatings are going to be used. I see way too many “green building” advertisements for foam ICFs! For the small handful of people who will actually carry through with a truly green sub-grade foundation, there are literally hundreds of thousands that will continue to wreck our planet. The book does call out those options that are more sustainable, but in general I think that encouraging people to go below grade is encouraging the use of the worst materials on offer.
Well, I still think that basements and underground or bermed housing should be vigorously encouraged… but only if they are built with sustainable materials, like earthbags, such are shown below. You can see that I did use a polyethylene liner, but I think that this a very minor part of the project when compared to the decades of utility and thermal value for this space.
What do you think?