So far as I understand from your question, you have a confirmed contract to build a commercial building but need money to start it.
You have some options. You may opt to have Construction Loans. Since you have confirmed contract in hand, that may not be difficult. http://www.nationalfinancer.com/mortgage_loans/construction_loan.php
The other options can be Bridge financing. http://www.nationalfinancer.com/mortgage_loans/bridge_loans.php but they are usually to relatively shorter period.
In any case, since you have confirmed contract in your hand, obtaining financing should not be a problem.
I hope this helps...
There are no "specific" schemes that finances solely on confirmed contracts. Please note that you will have to go for routine constructions loans but having "Confirmed" contracts is bound to make your job a lot easier.
I hope I am clear...