The collector/system design for the TEA system was developed in 1980 as a part of the very intense development that was occurring in the solar heating area during the 70's and 80's. It is certainly one of the most carefully designed and tested systems developed in this time period.
While the design is 30 years old, the system can be built today exactly as described in the construction manual, and will work quite well. There is surprisingly little to think about changing or improving, but here are few areas in which developments over the last 30 years might be worth incorporating:
In the design section, I would
say that the home insulation levels suggested are too low for a cold climate
home today. Today's homes should be built to better insulation and
infiltration standards, and this will in turn result in a smaller collector
area and less heat storage for a given solar fraction.
Rock bins for heat storage have
come under some criticism over the possibility of health problems from mold
forming in the rock bin. I'm not sure how valid these criticisms are,
or how difficult it is to avoid the problem. I suspect that it may be
highly dependent on climate, with dry climates being less susceptible.
Alternatives to using rock bin storage would include using something like the crawl space water container based heat storage schemes described in The Solar Air Heating Systems book, or the attic water container system used in this Norman Saunders home. Or, the collector can be sized small enough that the thermal mass of the home itself acts as the storage. A solar air heating collector of this type that produces too much heat at some times of year can simply be shut down, and will not overheat the house, as excessive passive gain might.
I believe that polycarbonate
glazing has progressed since the manual was done, and is a viable choice for
at least the wall collectors. Twin wall polycarbonate glazing with UV
filtering coatings (such as is used in many greenhouses today) is a good
material with high transmittance, good insulating properties, and long life.
It is also very easy to work with compared to glass. Single wall
corrugated polycarbonate glazing, such as SunTuf glazing could also be
considered. More on glazing materials ...
The control system might well
benefit from changes in electronic controls since the 80's.
Here is an example of one recent design that is based on the TEA design, but makes use of polycarbonate glazing
Gary May 25, 2009