If the design you took to the architect was a "green" design, you should already know that such design requests are not particularly familiar to local builders, and
would be costly.
1) First, I would have a local attorney write a letter
demanding (as only an attorney would do
) repayment of what you think is owed to you.
(Cost? Less than $200)
2) Second, to save on attorneys' fees, I'd then take the architectural firm to "Small-Claims Court":
In most cases, it'd be a waste of time, but a "Small-Claims Court" claim should cost you less than $20, and would expose the defendant to public exposure (in the press) and embarrassment (in the courtroom).
You won't recover 50% of what you've already "lost", but in any settlement that
would result, you might recover enough of your ill-spent funds to expand somewhat on your present construction.
