In my previous article, I had discussed the Tir Tairngire Ecovillage project as the grand scope of things. I had decided to rush parts of it, simply because it was already after midnight and I knew I’d have to re-address certain facets of the whole thing, which I’ve been doing for nearly a decade and a half. I had real problems with the 45d angle that has been forever evident in the location of my site, and it would really be hellishly inconvenient to rotate lots, adjust roads, or search for another site when I already OWN this one. It’s just not practical. That said, I’ve decided to reassess one of my biggest concerns: The 1/2 Acre (~0.2 ha) Homestead Greenhouse. I also was faced with the challenge of angling the buildings to make best use of the lower angle of the winter sun in the northern hemisphere.
Those little pyramids on stilts are great and all, since the focus of my research for next year when I build my own greenhouse units attached to my garage to prove the technology, and then apply that research to the purpose-built greenhouse to see if there is any advantage. I really think that, for this environment, I can do better. That said, I think I just did. 😀
What was really worrying me is that we need to build a sufficiently large greenhouse (as part of this particular version of the modular design units) to not only grow all the food for the household that they could ever want but enough variety to keep them from revolting. The last thing I want is a group of peasant farmers to lay siege to my castle (Wait… I get a CASTLE?!) with pitchforks and torches. As cool as that would be, I can’t imagine it ending well for anyone, much less their benevolent dicta… er… community leader. We also need excess to sell/barter for local goods, materials, labour and so on. Those 4 little greenhouses would do the trick, but I figured a re-design would settle some things. They were also in the wrong place.
For contrast, the smaller buildings are 15′ by 15′ (~5m square), with a 10′ (~3.5m) stemwall and a 8′ (~2.5m) tall peak on the pyramid. The building is also dug down 4′ (~1.5m) to help sequester more of the natural earth heat into the building and get away from ground-frost leeching away the warmth from the plants.
This new, larger building is 31′ (~10m) wide (as opposed to ~3m) and is 70′ (~21m) long. It is also a full 6′ (~2m) into the soil, with retaining walls, ditches and sumps keeping the water table down, though it’s pretty low as it is already. The angle on the left-hand side (in this case South-East. The footprint, by extension, is 31′ (~10m) by 70′ (~21m), which ends up being almost 2200 square feet (200 square meters). Not only that, but this greenhouse is 16′ (~5.5m) from the bottom right hand corner to the top of the wall (you can see the horizontal line delineating the straight wall to the curve). The curve, itself, raises an additional 10′ (~3m), making a total of 26′ (~8m) of building, and 20′ (~6m) above ground. This building is huge, and the angle of the slanted glazing is perpendicular to the noon-time sun in the pits of winter, so we should get some really good solar gains. The best part is, due to the temperature differentials and shape of the dome, we will get some natural convection currents to circulate air around the whole building and equalize the temperature across the whole building. When we get involved in building scaffolds, loose grills (think of the mesh decks on submarines. It will be a strong-enough platform and let light through, to boot!
You can see this larger greenhouse here, poking through the trees, amid a massive redesign of the lot to make better use of the sun. I’m not AS worried about heating the homes, since woodstoves and fireplaces can make due (especially when we get involved in coppicing trees for firewood). My concern was getting as much natural light into the greenhouse as possible, which is why I switched them around, and may even build the workshop ONTO the cottage, which will both eliminate two cold walls and make it easier to work in the winter, thereby avoid having to leave to travel from one building to another. That remains to be seen. Furthermore, this new layout actually FREES a great deal of space on the site to allow for a 60′ (~20m) swath of free space (seen below) for private/resident use. Gardens, trees, a playground, a koi pond, anything. Exciting!
My new layout has the HUGE greenhouse, has everything going for it, and though it could be a monster to build, and pricey to erect/install, we are looking for a sense of real permanence here. We need structures that will LAST, so we may actually go with aluminum or steel structures, heavy acrylic, glass or plastic panels and metal forms/frames. Once we build two or four of these units commercially, we can then worry about building them with timber-frame construction or something more sustainable.
We need to start from a place of stability and build a proverbial sky-scraper upon that solid foundation. Designs like this may be the key.