I've been to Arcosanti, and from an environmental point of view, it's a joke driven by architectural vision uninformed by any understanding of energy or thermodynamics.

The architect relies exclusively on cast concrete, one of the highest footprint, highest carbon materials you can use.  Concrete is a great material, but environmentally sensitive buildings should use it selectively, in ways that take advantage of its structural properties.  Using it to building a shade structure doesn't qualify.

The failings of the design are more obvious and visible, though, if you look at the living quarters: every single unit has a window air conditioner, and when I was there (in the summer, granted) every one of them was running.  Small AC units like that are the most inefficient way to provide cooling; if the designer had done his homework, he would have realized that some kind of supplementary cooling was going to be necessary -- it's really bloody hard to achieve comfort in that climate with purely passive design.  (It can be done, but barely.)  With that realization, he either could have gone back to the drawing board to improve his design, or accepted the need for additional cooling and designed accordingly, with a central chiller and a chilled water distribution system, or with earth channels for pre-cooling incoming, or with mini-split heat pumps, etc.

Dear green engineer,
I don't think you are seeing the project for what it is.
Arcosanti is the (concrete cast) physical embodiment of a vision. This vision was formed in the late sixties as a response to the rapid horizontal development of Phoenix and posed an alternative idea of a compact threedimensional city that is not based on air conditioning and car traffic, expanding across the landscape. It is documented in several beautiful books. The built result is almost by necessity a first draft with many faults and incomplete to boot. This may seem sad given the fact that it has been around and in progress since the early seventies.
But you can't deny the impressive perseverance and moral integrity with which the project has been realised by Paolo Soleri, largely self-funded. Although it didn't serve to stop Phoenix from growing into one of the largest and un-ecological cities on earth, I think it has had an influence on  architects and planners around the world. And the model it offers at least in its 'ideal' drawn version is still inspiring and relevant. The built Arcosanti is offering a glimpse of this. It is a special place to visit and stay and enjoy for itself. I have participated in a five-week workshop at Arcosanti and enjoyed living and working in one place so close to the Arizonian landscape. Being an architect's unfinished project, the community never really has seemed to have settled in, as it has in other alternative communities. Still there is a lot happening and there is an interesting dynamic between the centre and the 'temporary' settlement close to the agricultural land called 'camp'.
All in all it is an experiment, the success of which is defined by what we can learn from it, which each of us can do in his own way, but it takes more than pointing out the mistakes from a strictly enviromen-technical viewpoint.

Paul de Graaf, Rotterdam, the Netherlands

I think it is helpful here to point out that Arcosanti is an urban vision offering a different way of structuring our cities, addressing sustainable issues that go beyond the architectonical scale of a single-family house, such as commuter transport and its CO2.