! the first wofati - allerton abbey- version 0.7

And Ty, I really like your design. One of the main criticisms I have for some of these Wofati designs is just how small they are, which is fine for most people but others (such as myself) have rapidly expanding young families. And in colder months it's nice to have some room so occupants may retain some personal private space.

I have an idea for a circular wofati with a greenhouse dome/atrium in the middle. It would be 6 wofaties arranged in a hexagonal pattern, where it slopes away from the center. The sloping sides would have gables pointing downward and away from the greenhouse. This way, in the cold ourdoor months, you can still have some "outdoor" space with plenty of sunlight and also extend your growing season. I know that greenhouses can be somewhat controversial among permaculturalists, but they're also a nice way to maximize the output of your land and control every variable of growth, resulting in the capability to farm lucrative rare herbs for sale to the nutriceutical industry.

I'd like to share the design once I have it more developed. I call it the "Earth Mothership!"

Thanks.

Thermal lag has always been an important part of passive design. I used the R value to answer the question I get frequently as part of an introduction to why this is such a great idea, the umbrella is a significant enhancement. I will also re-post to include the protective layer that you mentioned. What is your recommendation on the minimum coverage at the change in planes at the ceiling/roof?

I find we could use a Mechanical Engineer to run a model analysis. that way we could tout EUI, Energy Star, USGBC, Daylit Area and Passive House ratings!

While integrating solar orientation into a wofati makes good sense, the wofati concept doesn't directly rely on it. Instead of necessarily aligning with the sun, a wofati is aligned with the hill. Drainage being of primary concern, wofatis have an uphill patio with drainage ditches that redirect water coming down the hill away and around the structure. So, not only does a wofati not necessarily have the open uphill side facing the southern sun, both Allerton Abbey and 0.8 are in fact aligned closer to having primarily western exposure. The idea being to test the concept of annualized thermal inertia without direct passive solar gain. Again, integrating paasive solar design into a wofati is a great idea, (in my humble opinion,) but these two wofatis in particular are built on roughly east-facing slopes, and so have uphill patios roughly to the west. Hope this helps.

Some of the biggest challenges in both 0.7 and 0.8 WOFATIs is that there wasn't much slope. This causes a huge issue of excavation, and hauling in material to cover the structure properly. Also, getting proper drainage away from the building when there is no slope is another difficult issue. Oehler's tried and true (and cheap) examples were always on a slope.

evan l pierce wrote:While integrating solar orientation into a wofati makes good sense, the wofati concept doesn't directly rely on it. Instead of necessarily aligning with the sun, a wofati is aligned with the hill. Drainage being of primary concern, wofatis have an uphill patio with drainage ditches that redirect water coming down the hill away and around the structure.

Yes, One of the things often not discussed or thought about is the wall opposite the uphill side of the wofati. In the original "underground" homes that the wafati is based on, there is a vertical wall about 10 feet away. The main reason is to form better water ways for drainage as mentioned. I think this wall also provides two other important functions. This wall is right across from the wall of the wofati with the most windows. My opinion is that the wall also acts as a radiated heat reflector. While glass has a poor R-value, it is even worse for it's ability to transmit radiated heat. This can be felt in a heated room (comfortable) where the part of the body facing a window with no window coverings will feel cold. This wall, if it is a light gray colour will actually reflect heat radiated from warm objects in the wafati back into the dwelling. I do not know how much this helps... I have never measured it

The wall also helps form a walled patio area. This will keep the air in the courtyard from moving around as much and it will tend to be somewhat warmer than air that is affected by the wind. This means that even though the windows have a low R-value, the temperature difference makes that R-value have a greater effect.

Ah, here is that third point people always make after claiming only two points I think a walled courtyard gathers solar heat (and light) no matter which direction the wafati is faced. I am assuming the lightest possible colour using local/found materials. Sun bleached wood or dry gray stone or adobe.

So my opinion is that the courtyard (fully surrounded by a vertical wall is best) is more important than than it is given credit for... in fact it does not seem to have been considered at all in any of the lab builds.

I agree that the labor savings of going into a hill or ridge is worthy of consideration, especially when all the labor is human-powered.

Seems I saw an example for a hot-wet adaptation where the soil from the evaporative cooling pond was used to pile on top of the surface built Wofati structure. Especially practical if you have access to a bulldozer and a front-end loader or the likes.

In other flat spots, the Kiva and Hogan which is partially or wholly submerged and balances the labor of cut and fill too.

Certainly in the hot-dry climates the walled courtyard has proven to be a winner for centuries.

I understand that one of the criteria that came up after the original design was to make them invisible from above therefore no uncovered roofs. But if that is not of concern I think covering the earth umbrella with a metal roof for water collection where water is scarce such as has been don in the SW would be valuable. A water tank could be put in the corner between the wide and narrow sections on each side.
My design would continue the roof with transparent material over the patio with hugal berm to absorb the water from the greenhouse roof. Winter gardening on the inside of the hugle during the winter and squash vines growing up the roof from the outside of the hugle during the summer for shade. Making optimum use of zone one for food production combined with weather protection.
To simplify the keeping a uniform depth of the earth umbrella I would make the logs for the roof make a compressive arch by stepping them in gradually.
If I get caught up I would like to download Sketchup again and do my shiplaped log design.

Why not cover the roof as originally designed, build a seperate roof cover for an outdoor pic-nic/meeting/shade spot. That roof can be your water collection area. Then you get the benefits of the thermal mass on top of your dwelling WOFATI

If the Wofati is earth covered then surely the water run off would be managed as part of the overall site strategy.

Having said that water flowing of a roof into a tank is an easy way to get drinking water and one that is used here in Oz a lot (our water never goes solid). As we face yet another drought it would be a major design consideration for me.

Alan Loy wrote:
Having said that water flowing of a roof into a tank is an easy way to get drinking water and one that is used here in Oz a lot (our water never goes solid). As we face yet another drought it would be a major design consideration for me.

This response is also for the above note about water harvesting.

Man has been drinking water from streams and wells for thousands of years. I do not think it is necessary to use metal roof to collect water for drinking (I just got email from the school as I am writing this... "Please be advised that there is a boil water advisory for Courtenay" ). I think it should also be possible to collect water from a live (soil with plants) roof with no ill effects. Running it through a sand filter may make it look nicer though